QUANTUM TELEPORTATIONQUANTUM TELEPORTATION

Whatrsquos Quantum Teleportation

Qubits and Quantum Computers

The theory

Introduction to the Quantum Teleportation

Quantum communication

TABLE OF CONTENTSTABLE OF CONTENTSTABLE OF CONTENTSTABLE OF CONTENTS

History applications further information

back to the introduction

WHAT IS QUANTUM TELEPORTATIONWHAT IS QUANTUM TELEPORTATION

Before giving a ldquocomplete definitionrdquo it is necessary to emphasize that it is a technique of communication that takes advantage of some unique aspects of the

Quantum Mechanics

a physical theory that describes

the behaviour of the electromagnetic radiation the matter and their interactions particularly with regard to the

phenomena typical of the length or energy scales of the atomic and subatomic particles

Development of the Quantum Mechanics

Development of the Quantum Mechanics

The Quantum Mechanics developed in the first half of the twentieth century due to the inconsistency of the classical mechanics and its inability to represent the experimental reality with particular reference to the light and the electron

The name Quantum Mechanics was introduced by Max Planck in the early twentieth century it is based on the fact that quantities such as energy or angular momentum of some physical systems can change in a discrete manner namely assuming only certain values named

QUANTAQUANTA

ldquowave-particle dualityrdquo

ldquowave-particle dualityrdquo

The basic characteristic that distinguishes the Quantum Mechanics from the Classical Mechanics is that

in the Quantum Mechanics the electromagnetic radiation and the matter are both described as a wave phenomenon and at the same time as particles in contrast to the Classical Mechanics where for example the light is described only as a wave and the electron only as a particle This unexpected and non intuitive property called

is the main reason for the failure of all classical theories developed until the

nineteenth century

Photoelectric Effect

Black body radiation

Atomic spectral linesWave properties of the electrons

QUANTUM MECHANICS PROVIDES SOLUTIONS WITHQUANTUM MECHANICS PROVIDES SOLUTIONS WITH

SOME EXPERIMENTAL SITUATIONS IN WHICH THE CLASSICAL PHYSICS FAILS

SOME EXPERIMENTAL SITUATIONS IN WHICH THE CLASSICAL PHYSICS FAILS

Plancks theory of the radiation of a black bodyEinsteins explanation of the photoelectric effectBohrs model of the hydrogen atom

Wavelength of Louis de Broglie

Max Planck found that the energy of the radiation emitted or absorbed by a black body is not emitted and absorbed continuously but

in discrete quantities called ldquoquantardquoThe main concept of his theory was based on the fact that each elementary oscillator (the electrons within the atom) could exchange energy with the environment only in the packets form given by

E = hʋ whereh = 663 times 10-34 Jmiddots = 663 x 10-27 ergmiddots is the Plancks constant

ʋ is the frequency of the oscillator

Albert Einstein was the first to recognize that this energy quantization of the emitted or absorbed radiation is a general

property of the electromagnetic radiation thinking of it as a set

of photons with energy E = hʋ

Niels Bohr applied the ideas of Einstein about energy quantization at the energy of an atom He proposed a model of the hydrogen atom which was a spectacular success in the

calculation of the wavelengths of the radiation emitted by the hydrogen atom

Does the light consist of particles or waves The answer depends on the type of observed phenomena

Schematic summary

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

The most common luminous phenomena observed such asreflection refraction interference and diffraction can be explained as wave phenomena

However the light that usually we imagine as a wave shows also particle properties when it interacts with the matter as demonstrated by the

photoelectric effect and scattering Compton

The same ldquowave-particlerdquo duality is also valid for the electrons

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

The electrons (and matter in general) which we usually think as particles have also

wave properties of interference and diffraction

Louis de Broglie in 1924 stated that all the particles had

wave properties

He affirmed that the wavelength associated with the wave of matter was inversely proportional to the mass ldquomrdquo of the particle and to its velocity ldquovrdquo so that

The product of mass and velocity takes the name of ldquomomentumrdquo p of the particle then the equation can be reformulated as ldquode Brogliersquos relationrdquo in the following way

where ldquohrdquo is Plancks constant

mv

h

p

h

The wave nature of the electrons was revealed showing that the electron beam can be diffracted The experiment was made for the first time in 1925 by two American scientists Clinton Davisson and Lester Germer They sent a beam of fast electrons against an isolated crystal of nickelThe regular arrangement of the atoms in the crystal acts as a grating capable of diffracting the waves Therefore a diffraction image was observed

GPThomson in 1927 operating at Aberdeen Scotland

showed that an electron beam produced a diffraction image passing also through a thin foil of gold as shown in the figure

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

Development of the Quantum Mechanics

Development of the Quantum Mechanics

The Quantum Mechanics developed in the first half of the twentieth century due to the inconsistency of the classical mechanics and its inability to represent the experimental reality with particular reference to the light and the electron

The name Quantum Mechanics was introduced by Max Planck in the early twentieth century it is based on the fact that quantities such as energy or angular momentum of some physical systems can change in a discrete manner namely assuming only certain values named

QUANTAQUANTA

ldquowave-particle dualityrdquo

ldquowave-particle dualityrdquo

The basic characteristic that distinguishes the Quantum Mechanics from the Classical Mechanics is that

in the Quantum Mechanics the electromagnetic radiation and the matter are both described as a wave phenomenon and at the same time as particles in contrast to the Classical Mechanics where for example the light is described only as a wave and the electron only as a particle This unexpected and non intuitive property called

is the main reason for the failure of all classical theories developed until the

nineteenth century

Photoelectric Effect

Black body radiation

Atomic spectral linesWave properties of the electrons

QUANTUM MECHANICS PROVIDES SOLUTIONS WITHQUANTUM MECHANICS PROVIDES SOLUTIONS WITH

SOME EXPERIMENTAL SITUATIONS IN WHICH THE CLASSICAL PHYSICS FAILS

SOME EXPERIMENTAL SITUATIONS IN WHICH THE CLASSICAL PHYSICS FAILS

Plancks theory of the radiation of a black bodyEinsteins explanation of the photoelectric effectBohrs model of the hydrogen atom

Wavelength of Louis de Broglie

Max Planck found that the energy of the radiation emitted or absorbed by a black body is not emitted and absorbed continuously but

in discrete quantities called ldquoquantardquoThe main concept of his theory was based on the fact that each elementary oscillator (the electrons within the atom) could exchange energy with the environment only in the packets form given by

E = hʋ whereh = 663 times 10-34 Jmiddots = 663 x 10-27 ergmiddots is the Plancks constant

ʋ is the frequency of the oscillator

Albert Einstein was the first to recognize that this energy quantization of the emitted or absorbed radiation is a general

property of the electromagnetic radiation thinking of it as a set

of photons with energy E = hʋ

Niels Bohr applied the ideas of Einstein about energy quantization at the energy of an atom He proposed a model of the hydrogen atom which was a spectacular success in the

calculation of the wavelengths of the radiation emitted by the hydrogen atom

Does the light consist of particles or waves The answer depends on the type of observed phenomena

Schematic summary

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

The most common luminous phenomena observed such asreflection refraction interference and diffraction can be explained as wave phenomena

However the light that usually we imagine as a wave shows also particle properties when it interacts with the matter as demonstrated by the

photoelectric effect and scattering Compton

The same ldquowave-particlerdquo duality is also valid for the electrons

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

The electrons (and matter in general) which we usually think as particles have also

wave properties of interference and diffraction

Louis de Broglie in 1924 stated that all the particles had

wave properties

He affirmed that the wavelength associated with the wave of matter was inversely proportional to the mass ldquomrdquo of the particle and to its velocity ldquovrdquo so that

The product of mass and velocity takes the name of ldquomomentumrdquo p of the particle then the equation can be reformulated as ldquode Brogliersquos relationrdquo in the following way

where ldquohrdquo is Plancks constant

mv

h

p

h

The wave nature of the electrons was revealed showing that the electron beam can be diffracted The experiment was made for the first time in 1925 by two American scientists Clinton Davisson and Lester Germer They sent a beam of fast electrons against an isolated crystal of nickelThe regular arrangement of the atoms in the crystal acts as a grating capable of diffracting the waves Therefore a diffraction image was observed

GPThomson in 1927 operating at Aberdeen Scotland

showed that an electron beam produced a diffraction image passing also through a thin foil of gold as shown in the figure

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

ldquowave-particle dualityrdquo

ldquowave-particle dualityrdquo

The basic characteristic that distinguishes the Quantum Mechanics from the Classical Mechanics is that

in the Quantum Mechanics the electromagnetic radiation and the matter are both described as a wave phenomenon and at the same time as particles in contrast to the Classical Mechanics where for example the light is described only as a wave and the electron only as a particle This unexpected and non intuitive property called

is the main reason for the failure of all classical theories developed until the

nineteenth century

Photoelectric Effect

Black body radiation

Atomic spectral linesWave properties of the electrons

QUANTUM MECHANICS PROVIDES SOLUTIONS WITHQUANTUM MECHANICS PROVIDES SOLUTIONS WITH

SOME EXPERIMENTAL SITUATIONS IN WHICH THE CLASSICAL PHYSICS FAILS

SOME EXPERIMENTAL SITUATIONS IN WHICH THE CLASSICAL PHYSICS FAILS

Plancks theory of the radiation of a black bodyEinsteins explanation of the photoelectric effectBohrs model of the hydrogen atom

Wavelength of Louis de Broglie

Max Planck found that the energy of the radiation emitted or absorbed by a black body is not emitted and absorbed continuously but

in discrete quantities called ldquoquantardquoThe main concept of his theory was based on the fact that each elementary oscillator (the electrons within the atom) could exchange energy with the environment only in the packets form given by

E = hʋ whereh = 663 times 10-34 Jmiddots = 663 x 10-27 ergmiddots is the Plancks constant

ʋ is the frequency of the oscillator

Albert Einstein was the first to recognize that this energy quantization of the emitted or absorbed radiation is a general

property of the electromagnetic radiation thinking of it as a set

of photons with energy E = hʋ

Niels Bohr applied the ideas of Einstein about energy quantization at the energy of an atom He proposed a model of the hydrogen atom which was a spectacular success in the

calculation of the wavelengths of the radiation emitted by the hydrogen atom

Does the light consist of particles or waves The answer depends on the type of observed phenomena

Schematic summary

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

The most common luminous phenomena observed such asreflection refraction interference and diffraction can be explained as wave phenomena

However the light that usually we imagine as a wave shows also particle properties when it interacts with the matter as demonstrated by the

photoelectric effect and scattering Compton

The same ldquowave-particlerdquo duality is also valid for the electrons

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

The electrons (and matter in general) which we usually think as particles have also

wave properties of interference and diffraction

Louis de Broglie in 1924 stated that all the particles had

wave properties

He affirmed that the wavelength associated with the wave of matter was inversely proportional to the mass ldquomrdquo of the particle and to its velocity ldquovrdquo so that

The product of mass and velocity takes the name of ldquomomentumrdquo p of the particle then the equation can be reformulated as ldquode Brogliersquos relationrdquo in the following way

where ldquohrdquo is Plancks constant

mv

h

p

h

The wave nature of the electrons was revealed showing that the electron beam can be diffracted The experiment was made for the first time in 1925 by two American scientists Clinton Davisson and Lester Germer They sent a beam of fast electrons against an isolated crystal of nickelThe regular arrangement of the atoms in the crystal acts as a grating capable of diffracting the waves Therefore a diffraction image was observed

GPThomson in 1927 operating at Aberdeen Scotland

showed that an electron beam produced a diffraction image passing also through a thin foil of gold as shown in the figure

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

Photoelectric Effect

Black body radiation

Atomic spectral linesWave properties of the electrons

QUANTUM MECHANICS PROVIDES SOLUTIONS WITHQUANTUM MECHANICS PROVIDES SOLUTIONS WITH

SOME EXPERIMENTAL SITUATIONS IN WHICH THE CLASSICAL PHYSICS FAILS

SOME EXPERIMENTAL SITUATIONS IN WHICH THE CLASSICAL PHYSICS FAILS

Plancks theory of the radiation of a black bodyEinsteins explanation of the photoelectric effectBohrs model of the hydrogen atom

Wavelength of Louis de Broglie

Max Planck found that the energy of the radiation emitted or absorbed by a black body is not emitted and absorbed continuously but

in discrete quantities called ldquoquantardquoThe main concept of his theory was based on the fact that each elementary oscillator (the electrons within the atom) could exchange energy with the environment only in the packets form given by

E = hʋ whereh = 663 times 10-34 Jmiddots = 663 x 10-27 ergmiddots is the Plancks constant

ʋ is the frequency of the oscillator

Albert Einstein was the first to recognize that this energy quantization of the emitted or absorbed radiation is a general

property of the electromagnetic radiation thinking of it as a set

of photons with energy E = hʋ

Niels Bohr applied the ideas of Einstein about energy quantization at the energy of an atom He proposed a model of the hydrogen atom which was a spectacular success in the

calculation of the wavelengths of the radiation emitted by the hydrogen atom

Does the light consist of particles or waves The answer depends on the type of observed phenomena

Schematic summary

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

The most common luminous phenomena observed such asreflection refraction interference and diffraction can be explained as wave phenomena

However the light that usually we imagine as a wave shows also particle properties when it interacts with the matter as demonstrated by the

photoelectric effect and scattering Compton

The same ldquowave-particlerdquo duality is also valid for the electrons

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

The electrons (and matter in general) which we usually think as particles have also

wave properties of interference and diffraction

Louis de Broglie in 1924 stated that all the particles had

wave properties

He affirmed that the wavelength associated with the wave of matter was inversely proportional to the mass ldquomrdquo of the particle and to its velocity ldquovrdquo so that

The product of mass and velocity takes the name of ldquomomentumrdquo p of the particle then the equation can be reformulated as ldquode Brogliersquos relationrdquo in the following way

where ldquohrdquo is Plancks constant

mv

h

p

h

The wave nature of the electrons was revealed showing that the electron beam can be diffracted The experiment was made for the first time in 1925 by two American scientists Clinton Davisson and Lester Germer They sent a beam of fast electrons against an isolated crystal of nickelThe regular arrangement of the atoms in the crystal acts as a grating capable of diffracting the waves Therefore a diffraction image was observed

GPThomson in 1927 operating at Aberdeen Scotland

showed that an electron beam produced a diffraction image passing also through a thin foil of gold as shown in the figure

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

Max Planck found that the energy of the radiation emitted or absorbed by a black body is not emitted and absorbed continuously but

in discrete quantities called ldquoquantardquoThe main concept of his theory was based on the fact that each elementary oscillator (the electrons within the atom) could exchange energy with the environment only in the packets form given by

E = hʋ whereh = 663 times 10-34 Jmiddots = 663 x 10-27 ergmiddots is the Plancks constant

ʋ is the frequency of the oscillator

Albert Einstein was the first to recognize that this energy quantization of the emitted or absorbed radiation is a general

property of the electromagnetic radiation thinking of it as a set

of photons with energy E = hʋ

Niels Bohr applied the ideas of Einstein about energy quantization at the energy of an atom He proposed a model of the hydrogen atom which was a spectacular success in the

calculation of the wavelengths of the radiation emitted by the hydrogen atom

Does the light consist of particles or waves The answer depends on the type of observed phenomena

Schematic summary

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

The most common luminous phenomena observed such asreflection refraction interference and diffraction can be explained as wave phenomena

However the light that usually we imagine as a wave shows also particle properties when it interacts with the matter as demonstrated by the

photoelectric effect and scattering Compton

The same ldquowave-particlerdquo duality is also valid for the electrons

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

The electrons (and matter in general) which we usually think as particles have also

wave properties of interference and diffraction

Louis de Broglie in 1924 stated that all the particles had

wave properties

He affirmed that the wavelength associated with the wave of matter was inversely proportional to the mass ldquomrdquo of the particle and to its velocity ldquovrdquo so that

The product of mass and velocity takes the name of ldquomomentumrdquo p of the particle then the equation can be reformulated as ldquode Brogliersquos relationrdquo in the following way

where ldquohrdquo is Plancks constant

mv

h

p

h

The wave nature of the electrons was revealed showing that the electron beam can be diffracted The experiment was made for the first time in 1925 by two American scientists Clinton Davisson and Lester Germer They sent a beam of fast electrons against an isolated crystal of nickelThe regular arrangement of the atoms in the crystal acts as a grating capable of diffracting the waves Therefore a diffraction image was observed

GPThomson in 1927 operating at Aberdeen Scotland

showed that an electron beam produced a diffraction image passing also through a thin foil of gold as shown in the figure

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

Does the light consist of particles or waves The answer depends on the type of observed phenomena

Schematic summary

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

Wave ndash Particle Duality WAVE AND PARTICLE NATURE OF THE LIGHT

The most common luminous phenomena observed such asreflection refraction interference and diffraction can be explained as wave phenomena

However the light that usually we imagine as a wave shows also particle properties when it interacts with the matter as demonstrated by the

photoelectric effect and scattering Compton

The same ldquowave-particlerdquo duality is also valid for the electrons

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

The electrons (and matter in general) which we usually think as particles have also

wave properties of interference and diffraction

Louis de Broglie in 1924 stated that all the particles had

wave properties

He affirmed that the wavelength associated with the wave of matter was inversely proportional to the mass ldquomrdquo of the particle and to its velocity ldquovrdquo so that

The product of mass and velocity takes the name of ldquomomentumrdquo p of the particle then the equation can be reformulated as ldquode Brogliersquos relationrdquo in the following way

where ldquohrdquo is Plancks constant

mv

h

p

h

The wave nature of the electrons was revealed showing that the electron beam can be diffracted The experiment was made for the first time in 1925 by two American scientists Clinton Davisson and Lester Germer They sent a beam of fast electrons against an isolated crystal of nickelThe regular arrangement of the atoms in the crystal acts as a grating capable of diffracting the waves Therefore a diffraction image was observed

GPThomson in 1927 operating at Aberdeen Scotland

showed that an electron beam produced a diffraction image passing also through a thin foil of gold as shown in the figure

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

The most common luminous phenomena observed such asreflection refraction interference and diffraction can be explained as wave phenomena

However the light that usually we imagine as a wave shows also particle properties when it interacts with the matter as demonstrated by the

photoelectric effect and scattering Compton

The same ldquowave-particlerdquo duality is also valid for the electrons

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

The electrons (and matter in general) which we usually think as particles have also

wave properties of interference and diffraction

Louis de Broglie in 1924 stated that all the particles had

wave properties

He affirmed that the wavelength associated with the wave of matter was inversely proportional to the mass ldquomrdquo of the particle and to its velocity ldquovrdquo so that

The product of mass and velocity takes the name of ldquomomentumrdquo p of the particle then the equation can be reformulated as ldquode Brogliersquos relationrdquo in the following way

where ldquohrdquo is Plancks constant

mv

h

p

h

The wave nature of the electrons was revealed showing that the electron beam can be diffracted The experiment was made for the first time in 1925 by two American scientists Clinton Davisson and Lester Germer They sent a beam of fast electrons against an isolated crystal of nickelThe regular arrangement of the atoms in the crystal acts as a grating capable of diffracting the waves Therefore a diffraction image was observed

GPThomson in 1927 operating at Aberdeen Scotland

showed that an electron beam produced a diffraction image passing also through a thin foil of gold as shown in the figure

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

Wave ndash Particle DualityWAVE NATURE OF THE MATTER

The electrons (and matter in general) which we usually think as particles have also

wave properties of interference and diffraction

Louis de Broglie in 1924 stated that all the particles had

wave properties

He affirmed that the wavelength associated with the wave of matter was inversely proportional to the mass ldquomrdquo of the particle and to its velocity ldquovrdquo so that

The product of mass and velocity takes the name of ldquomomentumrdquo p of the particle then the equation can be reformulated as ldquode Brogliersquos relationrdquo in the following way

where ldquohrdquo is Plancks constant

mv

h

p

h

The wave nature of the electrons was revealed showing that the electron beam can be diffracted The experiment was made for the first time in 1925 by two American scientists Clinton Davisson and Lester Germer They sent a beam of fast electrons against an isolated crystal of nickelThe regular arrangement of the atoms in the crystal acts as a grating capable of diffracting the waves Therefore a diffraction image was observed

GPThomson in 1927 operating at Aberdeen Scotland

showed that an electron beam produced a diffraction image passing also through a thin foil of gold as shown in the figure

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

Louis de Broglie in 1924 stated that all the particles had

wave properties

He affirmed that the wavelength associated with the wave of matter was inversely proportional to the mass ldquomrdquo of the particle and to its velocity ldquovrdquo so that

The product of mass and velocity takes the name of ldquomomentumrdquo p of the particle then the equation can be reformulated as ldquode Brogliersquos relationrdquo in the following way

where ldquohrdquo is Plancks constant

mv

h

p

h

The wave nature of the electrons was revealed showing that the electron beam can be diffracted The experiment was made for the first time in 1925 by two American scientists Clinton Davisson and Lester Germer They sent a beam of fast electrons against an isolated crystal of nickelThe regular arrangement of the atoms in the crystal acts as a grating capable of diffracting the waves Therefore a diffraction image was observed

GPThomson in 1927 operating at Aberdeen Scotland

showed that an electron beam produced a diffraction image passing also through a thin foil of gold as shown in the figure

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

The wave nature of the electrons was revealed showing that the electron beam can be diffracted The experiment was made for the first time in 1925 by two American scientists Clinton Davisson and Lester Germer They sent a beam of fast electrons against an isolated crystal of nickelThe regular arrangement of the atoms in the crystal acts as a grating capable of diffracting the waves Therefore a diffraction image was observed

GPThomson in 1927 operating at Aberdeen Scotland

showed that an electron beam produced a diffraction image passing also through a thin foil of gold as shown in the figure

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

Thus even the electron like the photon reveals a double behaviour

It is not a quite classical particle but it can have a

detectable wave behaviour

The wavelength

associated with it is

inversely proportional to its momentum

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

The ldquode Brogliersquos relationrdquo also applies to

the photons

λ = cν = hchν = hcE = h(Ec) = hp

In fact the momentum of a photon is related to its energy by the relation p = Ec

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

We can conclude by saying that

All holders of momentum and energyelectrons atoms light sound

and so on have corpuscular and wave characteristicsrdquo

CONCLUSION

back to the table of contents

Classical mechanics is a physical theory of deterministic nature

It is governed by the principle of causality

Quantum mechanics is a physical theory of probabilistic nature

It is based on the concept of probability and observation

COMPARISON BETWEEN CLASSICAL MECHANICS AND QUANTUM MECHANICS

COMPARISON BETWEEN CLASSICAL MECHANICS AND QUANTUM MECHANICS

The nature of the Quantum Mechanics is indeterministic namely it is based on the concept of probability and observationFor example if somebody wants accurately to know the location of an electron in an atom he will never know the speed and vice versa

Basically

According to the Classical Mechanics due to the discoveries of Newton and Galileo Galilei if you know the properties of a body (mass shape etc) its initial conditions of motion (position velocity etc) and the external conditions (force fields etc) it is possible to determine exactly its behavior instant by instantTherefore within the framework of the Classical Mechanics the principle of causality applies namely in nature nothing happens by chance each event is determined by an identified cause

The famous example of Schroumldingers cat clarifies the nature of Quantum Mechanics

The famous example of Schroumldingers cat clarifies the nature of Quantum Mechanics

In this example a cat is closed in a box with a machine connected to a bottle containing poison The machine starts when a radioactive element decays breaking the bottle containing poisonFrom the outside the cat inside the box can be alive or dead because you donrsquot know if the radioactive element has decayed or not According to the Quantum Mechanics the cat is in both states ldquoalive and deadrdquo it is in a superposition of states

state alive and state dead

Only the observation phase freezes the state of the cat determining its fate

The wave and the corpuscular nature of the particles is related by the

ldquoHeisenbergrsquos Uncertainty Principlerdquo

In order to speak of Quantum Teleportation it is necessary to take into account the wave and the corpuscular nature of electromagnetic radiation and of matter

That is to say

ldquoWave ndash Particlerdquo dualityfor the light and the matter

Formulated by the German scientist Werner Heisenberg in 1927 this principle states that

ldquoif the uncertainty Δx on the position x of a particle is very little the uncertainty Δp on the

momentum p is large and vice versa

a) The x position of the particle is badly defined this allows to specify its momentum p represented by the arrow with acceptable accuracy b) The x position of the particle is well defined this prevents to specify precisely its momentum p

a)

b)

Representation of the Heisenbergrsquos Uncertainty Principle

The math expression of the principle is

ΔxΔp ge h4π

or

ΔxΔp ge ћ2

ldquoits impossible to know simultaneously and with accuracy the momentum and the position

of a particlerdquo

According to the Heisenbergrsquos Uncertainty Principle

we can say that

The same uncertainty affects the simultaneous measurement of energy E and time t

ΔEΔt ge ћ2

This means that

ldquoin a very short time the energy is not definedrdquo

In other words

ldquothe product of the uncertainties of two simultaneous measurements can

not be less than a given constantrdquo

back to the table of contents

The nature of the Quantum Mechanics is indeterministic namely it is based on the concept of probability and observationFor example if somebody wants accurately to know the location of an electron in an atom he will never know the speed and vice versa

Basically

According to the Classical Mechanics due to the discoveries of Newton and Galileo Galilei if you know the properties of a body (mass shape etc) its initial conditions of motion (position velocity etc) and the external conditions (force fields etc) it is possible to determine exactly its behavior instant by instantTherefore within the framework of the Classical Mechanics the principle of causality applies namely in nature nothing happens by chance each event is determined by an identified cause

The famous example of Schroumldingers cat clarifies the nature of Quantum Mechanics

The famous example of Schroumldingers cat clarifies the nature of Quantum Mechanics

In this example a cat is closed in a box with a machine connected to a bottle containing poison The machine starts when a radioactive element decays breaking the bottle containing poisonFrom the outside the cat inside the box can be alive or dead because you donrsquot know if the radioactive element has decayed or not According to the Quantum Mechanics the cat is in both states ldquoalive and deadrdquo it is in a superposition of states

state alive and state dead

Only the observation phase freezes the state of the cat determining its fate

The wave and the corpuscular nature of the particles is related by the

ldquoHeisenbergrsquos Uncertainty Principlerdquo

In order to speak of Quantum Teleportation it is necessary to take into account the wave and the corpuscular nature of electromagnetic radiation and of matter

That is to say

ldquoWave ndash Particlerdquo dualityfor the light and the matter

Formulated by the German scientist Werner Heisenberg in 1927 this principle states that

ldquoif the uncertainty Δx on the position x of a particle is very little the uncertainty Δp on the

momentum p is large and vice versa

a) The x position of the particle is badly defined this allows to specify its momentum p represented by the arrow with acceptable accuracy b) The x position of the particle is well defined this prevents to specify precisely its momentum p

a)

b)

Representation of the Heisenbergrsquos Uncertainty Principle

The math expression of the principle is

ΔxΔp ge h4π

or

ΔxΔp ge ћ2

ldquoits impossible to know simultaneously and with accuracy the momentum and the position

of a particlerdquo

According to the Heisenbergrsquos Uncertainty Principle

we can say that

The same uncertainty affects the simultaneous measurement of energy E and time t

ΔEΔt ge ћ2

This means that

ldquoin a very short time the energy is not definedrdquo

In other words

ldquothe product of the uncertainties of two simultaneous measurements can

not be less than a given constantrdquo

back to the table of contents

The famous example of Schroumldingers cat clarifies the nature of Quantum Mechanics

The famous example of Schroumldingers cat clarifies the nature of Quantum Mechanics

In this example a cat is closed in a box with a machine connected to a bottle containing poison The machine starts when a radioactive element decays breaking the bottle containing poisonFrom the outside the cat inside the box can be alive or dead because you donrsquot know if the radioactive element has decayed or not According to the Quantum Mechanics the cat is in both states ldquoalive and deadrdquo it is in a superposition of states

state alive and state dead

Only the observation phase freezes the state of the cat determining its fate

The wave and the corpuscular nature of the particles is related by the

ldquoHeisenbergrsquos Uncertainty Principlerdquo

In order to speak of Quantum Teleportation it is necessary to take into account the wave and the corpuscular nature of electromagnetic radiation and of matter

That is to say

ldquoWave ndash Particlerdquo dualityfor the light and the matter

Formulated by the German scientist Werner Heisenberg in 1927 this principle states that

ldquoif the uncertainty Δx on the position x of a particle is very little the uncertainty Δp on the

momentum p is large and vice versa

a) The x position of the particle is badly defined this allows to specify its momentum p represented by the arrow with acceptable accuracy b) The x position of the particle is well defined this prevents to specify precisely its momentum p

a)

b)

Representation of the Heisenbergrsquos Uncertainty Principle

The math expression of the principle is

ΔxΔp ge h4π

or

ΔxΔp ge ћ2

ldquoits impossible to know simultaneously and with accuracy the momentum and the position

of a particlerdquo

According to the Heisenbergrsquos Uncertainty Principle

we can say that

The same uncertainty affects the simultaneous measurement of energy E and time t

ΔEΔt ge ћ2

This means that

ldquoin a very short time the energy is not definedrdquo

In other words

ldquothe product of the uncertainties of two simultaneous measurements can

not be less than a given constantrdquo

back to the table of contents

In this example a cat is closed in a box with a machine connected to a bottle containing poison The machine starts when a radioactive element decays breaking the bottle containing poisonFrom the outside the cat inside the box can be alive or dead because you donrsquot know if the radioactive element has decayed or not According to the Quantum Mechanics the cat is in both states ldquoalive and deadrdquo it is in a superposition of states

state alive and state dead

Only the observation phase freezes the state of the cat determining its fate

The wave and the corpuscular nature of the particles is related by the

ldquoHeisenbergrsquos Uncertainty Principlerdquo

In order to speak of Quantum Teleportation it is necessary to take into account the wave and the corpuscular nature of electromagnetic radiation and of matter

That is to say

ldquoWave ndash Particlerdquo dualityfor the light and the matter

Formulated by the German scientist Werner Heisenberg in 1927 this principle states that

ldquoif the uncertainty Δx on the position x of a particle is very little the uncertainty Δp on the

momentum p is large and vice versa

a) The x position of the particle is badly defined this allows to specify its momentum p represented by the arrow with acceptable accuracy b) The x position of the particle is well defined this prevents to specify precisely its momentum p

a)

b)

Representation of the Heisenbergrsquos Uncertainty Principle

The math expression of the principle is

ΔxΔp ge h4π

or

ΔxΔp ge ћ2

ldquoits impossible to know simultaneously and with accuracy the momentum and the position

of a particlerdquo

According to the Heisenbergrsquos Uncertainty Principle

we can say that

The same uncertainty affects the simultaneous measurement of energy E and time t

ΔEΔt ge ћ2

This means that

ldquoin a very short time the energy is not definedrdquo

In other words

ldquothe product of the uncertainties of two simultaneous measurements can

not be less than a given constantrdquo

back to the table of contents

The wave and the corpuscular nature of the particles is related by the

ldquoHeisenbergrsquos Uncertainty Principlerdquo

In order to speak of Quantum Teleportation it is necessary to take into account the wave and the corpuscular nature of electromagnetic radiation and of matter

That is to say

ldquoWave ndash Particlerdquo dualityfor the light and the matter

Formulated by the German scientist Werner Heisenberg in 1927 this principle states that

ldquoif the uncertainty Δx on the position x of a particle is very little the uncertainty Δp on the

momentum p is large and vice versa

a) The x position of the particle is badly defined this allows to specify its momentum p represented by the arrow with acceptable accuracy b) The x position of the particle is well defined this prevents to specify precisely its momentum p

a)

b)

Representation of the Heisenbergrsquos Uncertainty Principle

The math expression of the principle is

ΔxΔp ge h4π

or

ΔxΔp ge ћ2

ldquoits impossible to know simultaneously and with accuracy the momentum and the position

of a particlerdquo

According to the Heisenbergrsquos Uncertainty Principle

we can say that

The same uncertainty affects the simultaneous measurement of energy E and time t

ΔEΔt ge ћ2

This means that

ldquoin a very short time the energy is not definedrdquo

In other words

ldquothe product of the uncertainties of two simultaneous measurements can

not be less than a given constantrdquo

back to the table of contents

Formulated by the German scientist Werner Heisenberg in 1927 this principle states that

ldquoif the uncertainty Δx on the position x of a particle is very little the uncertainty Δp on the

momentum p is large and vice versa

a) The x position of the particle is badly defined this allows to specify its momentum p represented by the arrow with acceptable accuracy b) The x position of the particle is well defined this prevents to specify precisely its momentum p

a)

b)

Representation of the Heisenbergrsquos Uncertainty Principle

The math expression of the principle is

ΔxΔp ge h4π

or

ΔxΔp ge ћ2

ldquoits impossible to know simultaneously and with accuracy the momentum and the position

of a particlerdquo

According to the Heisenbergrsquos Uncertainty Principle

we can say that

The same uncertainty affects the simultaneous measurement of energy E and time t

ΔEΔt ge ћ2

This means that

ldquoin a very short time the energy is not definedrdquo

In other words

ldquothe product of the uncertainties of two simultaneous measurements can

not be less than a given constantrdquo

back to the table of contents

The math expression of the principle is

ΔxΔp ge h4π

or

ΔxΔp ge ћ2

ldquoits impossible to know simultaneously and with accuracy the momentum and the position

of a particlerdquo

According to the Heisenbergrsquos Uncertainty Principle

we can say that

The same uncertainty affects the simultaneous measurement of energy E and time t

ΔEΔt ge ћ2

This means that

ldquoin a very short time the energy is not definedrdquo

In other words

ldquothe product of the uncertainties of two simultaneous measurements can

not be less than a given constantrdquo

back to the table of contents

The same uncertainty affects the simultaneous measurement of energy E and time t

ΔEΔt ge ћ2

This means that

ldquoin a very short time the energy is not definedrdquo

In other words

ldquothe product of the uncertainties of two simultaneous measurements can

not be less than a given constantrdquo

back to the table of contents

In other words

ldquothe product of the uncertainties of two simultaneous measurements can

not be less than a given constantrdquo

back to the table of contents

According to Quantum Teleportation itrsquos possible to transfer the quantum state of a

particle (for example the state of polarization in the case of a photon) to

large distances

It is not the particle itself to be transferred but the receiver takes exactly the same state of polarization of the transmitter The Heisenbergrsquos Uncertainty Principle prohibits the exact knowledge of the state of the transmitted photon but a property called entanglement makes sure that this is not a problem for the teleportation

Quantum communication Quantum communication

STAR TREK TELEPORTATION ALLOWS

the disappearance of an object from one location and the simultaneous reappearance of the same object in another position of the space without having to travel boring intermediate kilometers and without any vehicle

Teleportation allows to make travels more comfortable than those made with an ordinary spacecraft but this involves the violation of the speed limits imposed by the theory of the relativity

According to this theory nothing can travel faster than light

In the science fiction teleportation procedure varies from story to story and generally takes place in the following way

the original object to teleport is subjected to a scan to extract the necessary information to describe it

A transmitter transfers the information to a receiving station and this is used to get an exact replica of the original In some cases the matter that composes the original is also transferred to the receiving station as some type of energy In other cases the replica of the original uses atoms and molecules already present at the place of arrival

In science fiction stories

According to Quantum Mechanics a similar teleportation is impossible even theoretically in fact

the Heisenbergrsquos Uncertainty Principle declares the impossibility of knowing at the same time with arbitrary precision the position and the velocity of a particle

A perfect scanning of the object involves the knowledge without uncertainty of the position and the velocity of each atom and each electron then teleportation is impossible

Heisenbergrsquos principle is also applied to other pairs of quantities and this expresses the impossibility of measuring without error the quantum state of an object

All these difficulties in Star Trek are overcome by the prodigious

Heisenbergrsquos compensator

BUT

The science-fiction dream of projecting objects from one place to another is now a reality at least for

light particles photons

although it remains for now still a fantasy for macroscopic objects

It is a technique of communication within

Quantum Informatics ldquothis is a group of calculation methods and their study that use

the QUANTA to store and process informationrdquo

The technique of Quantum Teleportation allows under certain restrictions the

transfer of a quantum statesuch as the state of polarization of the photons the spin state of the

electrons or the excitation state of the atoms

to a point arbitrarily far

This involves the effect called

QUANTUM ENTANGLEMENT

QUANTUM TELEPORTATION Definition

QUANTUM TELEPORTATION Definition

It can be said that

by Quantum Teleportation there is not a transfer in the same way as in Star Trek but it is possible through the

phenomenon of entanglement

to transfer (instantly) featuresldquo (quantum states) of photons atoms ions

in other photons atoms ions placed at any distance

The quantum entanglement was suggested for the first time in 1926 by Erwin Schroumldinger who was also the first to introduce in 1935 the term entanglement

Quantum entanglement is a quantum phenomenon which has no classic equivalent According to this phenomenon each quantum state (eg polarization of the photons spin state of the electrons) of two or more physical systems depends on the state of each of them even if they are spatially separated

The quantum entanglement implies the presence of remote correlations between the observable physical quantities of the involved systems so that the non-local character of quantum theory is established

The phenomenon of entanglement therefore violates the principle of locality in which what happens in one place can NOT immediately affect what happens in another place

Albert Einstein despite the important contributions given to the quantum theory never accepted that a particle could instantaneously influence another particle Therefore he tried to prove that the violation of locality was only apparent but from time to time his attempts were clinched by his opponents

QUANTUM ENTANGLEMENT QUANTUM ENTANGLEMENT

In 1982 the physicist Alain Aspect with a series of sophisticated experiments demonstrated the existence of the entanglement and then the inconsistency of the

position of Einstein

In October 1998 the phenomenon of the entanglement was finally confirmed by the success of a teleportation

experiment performed by the Institute of Technology (Caltech) in Pasadena California

LEARN MORE ABOUT ldquoENTANGLEMENTrdquoLEARN MORE ABOUT ldquoENTANGLEMENTrdquo

If two particles interact for a certain period of time and then they are separated when one of them is stimulated so that it changes its state instantly a similar stress is manifested on the second particle whatever the distance between the particles in other words the second particle changes instantaneously its state

This phenomenon is called Phenomenon of Entanglement

A simple experiment about the Phenomenon of Entanglementrdquo

two particles ldquotwinsrdquo are launched in opposite directionsIf the particle 1 during its journey meets a magnet that deflects it upward the particle 2 instead of continuing its trajectory in a straight line deflects its direction at the same time assuming a motion contrary to that of the particle 1

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

STAR TREK TELEPORTATION ALLOWS

the disappearance of an object from one location and the simultaneous reappearance of the same object in another position of the space without having to travel boring intermediate kilometers and without any vehicle

Teleportation allows to make travels more comfortable than those made with an ordinary spacecraft but this involves the violation of the speed limits imposed by the theory of the relativity

According to this theory nothing can travel faster than light

In the science fiction teleportation procedure varies from story to story and generally takes place in the following way

the original object to teleport is subjected to a scan to extract the necessary information to describe it

A transmitter transfers the information to a receiving station and this is used to get an exact replica of the original In some cases the matter that composes the original is also transferred to the receiving station as some type of energy In other cases the replica of the original uses atoms and molecules already present at the place of arrival

In science fiction stories

According to Quantum Mechanics a similar teleportation is impossible even theoretically in fact

the Heisenbergrsquos Uncertainty Principle declares the impossibility of knowing at the same time with arbitrary precision the position and the velocity of a particle

A perfect scanning of the object involves the knowledge without uncertainty of the position and the velocity of each atom and each electron then teleportation is impossible

Heisenbergrsquos principle is also applied to other pairs of quantities and this expresses the impossibility of measuring without error the quantum state of an object

All these difficulties in Star Trek are overcome by the prodigious

Heisenbergrsquos compensator

BUT

The science-fiction dream of projecting objects from one place to another is now a reality at least for

light particles photons

although it remains for now still a fantasy for macroscopic objects

It is a technique of communication within

Quantum Informatics ldquothis is a group of calculation methods and their study that use

the QUANTA to store and process informationrdquo

The technique of Quantum Teleportation allows under certain restrictions the

transfer of a quantum statesuch as the state of polarization of the photons the spin state of the

electrons or the excitation state of the atoms

to a point arbitrarily far

This involves the effect called

QUANTUM ENTANGLEMENT

QUANTUM TELEPORTATION Definition

QUANTUM TELEPORTATION Definition

It can be said that

by Quantum Teleportation there is not a transfer in the same way as in Star Trek but it is possible through the

phenomenon of entanglement

to transfer (instantly) featuresldquo (quantum states) of photons atoms ions

in other photons atoms ions placed at any distance

The quantum entanglement was suggested for the first time in 1926 by Erwin Schroumldinger who was also the first to introduce in 1935 the term entanglement

Quantum entanglement is a quantum phenomenon which has no classic equivalent According to this phenomenon each quantum state (eg polarization of the photons spin state of the electrons) of two or more physical systems depends on the state of each of them even if they are spatially separated

The quantum entanglement implies the presence of remote correlations between the observable physical quantities of the involved systems so that the non-local character of quantum theory is established

The phenomenon of entanglement therefore violates the principle of locality in which what happens in one place can NOT immediately affect what happens in another place

Albert Einstein despite the important contributions given to the quantum theory never accepted that a particle could instantaneously influence another particle Therefore he tried to prove that the violation of locality was only apparent but from time to time his attempts were clinched by his opponents

QUANTUM ENTANGLEMENT QUANTUM ENTANGLEMENT

In 1982 the physicist Alain Aspect with a series of sophisticated experiments demonstrated the existence of the entanglement and then the inconsistency of the

position of Einstein

In October 1998 the phenomenon of the entanglement was finally confirmed by the success of a teleportation

experiment performed by the Institute of Technology (Caltech) in Pasadena California

LEARN MORE ABOUT ldquoENTANGLEMENTrdquoLEARN MORE ABOUT ldquoENTANGLEMENTrdquo

If two particles interact for a certain period of time and then they are separated when one of them is stimulated so that it changes its state instantly a similar stress is manifested on the second particle whatever the distance between the particles in other words the second particle changes instantaneously its state

This phenomenon is called Phenomenon of Entanglement

A simple experiment about the Phenomenon of Entanglementrdquo

two particles ldquotwinsrdquo are launched in opposite directionsIf the particle 1 during its journey meets a magnet that deflects it upward the particle 2 instead of continuing its trajectory in a straight line deflects its direction at the same time assuming a motion contrary to that of the particle 1

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

Teleportation allows to make travels more comfortable than those made with an ordinary spacecraft but this involves the violation of the speed limits imposed by the theory of the relativity

According to this theory nothing can travel faster than light

In the science fiction teleportation procedure varies from story to story and generally takes place in the following way

the original object to teleport is subjected to a scan to extract the necessary information to describe it

A transmitter transfers the information to a receiving station and this is used to get an exact replica of the original In some cases the matter that composes the original is also transferred to the receiving station as some type of energy In other cases the replica of the original uses atoms and molecules already present at the place of arrival

In science fiction stories

According to Quantum Mechanics a similar teleportation is impossible even theoretically in fact

the Heisenbergrsquos Uncertainty Principle declares the impossibility of knowing at the same time with arbitrary precision the position and the velocity of a particle

A perfect scanning of the object involves the knowledge without uncertainty of the position and the velocity of each atom and each electron then teleportation is impossible

Heisenbergrsquos principle is also applied to other pairs of quantities and this expresses the impossibility of measuring without error the quantum state of an object

All these difficulties in Star Trek are overcome by the prodigious

Heisenbergrsquos compensator

BUT

The science-fiction dream of projecting objects from one place to another is now a reality at least for

light particles photons

although it remains for now still a fantasy for macroscopic objects

It is a technique of communication within

Quantum Informatics ldquothis is a group of calculation methods and their study that use

the QUANTA to store and process informationrdquo

The technique of Quantum Teleportation allows under certain restrictions the

transfer of a quantum statesuch as the state of polarization of the photons the spin state of the

electrons or the excitation state of the atoms

to a point arbitrarily far

This involves the effect called

QUANTUM ENTANGLEMENT

QUANTUM TELEPORTATION Definition

QUANTUM TELEPORTATION Definition

It can be said that

by Quantum Teleportation there is not a transfer in the same way as in Star Trek but it is possible through the

phenomenon of entanglement

to transfer (instantly) featuresldquo (quantum states) of photons atoms ions

in other photons atoms ions placed at any distance

The quantum entanglement was suggested for the first time in 1926 by Erwin Schroumldinger who was also the first to introduce in 1935 the term entanglement

Quantum entanglement is a quantum phenomenon which has no classic equivalent According to this phenomenon each quantum state (eg polarization of the photons spin state of the electrons) of two or more physical systems depends on the state of each of them even if they are spatially separated

The quantum entanglement implies the presence of remote correlations between the observable physical quantities of the involved systems so that the non-local character of quantum theory is established

The phenomenon of entanglement therefore violates the principle of locality in which what happens in one place can NOT immediately affect what happens in another place

Albert Einstein despite the important contributions given to the quantum theory never accepted that a particle could instantaneously influence another particle Therefore he tried to prove that the violation of locality was only apparent but from time to time his attempts were clinched by his opponents

QUANTUM ENTANGLEMENT QUANTUM ENTANGLEMENT

In 1982 the physicist Alain Aspect with a series of sophisticated experiments demonstrated the existence of the entanglement and then the inconsistency of the

position of Einstein

In October 1998 the phenomenon of the entanglement was finally confirmed by the success of a teleportation

experiment performed by the Institute of Technology (Caltech) in Pasadena California

LEARN MORE ABOUT ldquoENTANGLEMENTrdquoLEARN MORE ABOUT ldquoENTANGLEMENTrdquo

If two particles interact for a certain period of time and then they are separated when one of them is stimulated so that it changes its state instantly a similar stress is manifested on the second particle whatever the distance between the particles in other words the second particle changes instantaneously its state

This phenomenon is called Phenomenon of Entanglement

A simple experiment about the Phenomenon of Entanglementrdquo

two particles ldquotwinsrdquo are launched in opposite directionsIf the particle 1 during its journey meets a magnet that deflects it upward the particle 2 instead of continuing its trajectory in a straight line deflects its direction at the same time assuming a motion contrary to that of the particle 1

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

According to Quantum Mechanics a similar teleportation is impossible even theoretically in fact

the Heisenbergrsquos Uncertainty Principle declares the impossibility of knowing at the same time with arbitrary precision the position and the velocity of a particle

A perfect scanning of the object involves the knowledge without uncertainty of the position and the velocity of each atom and each electron then teleportation is impossible

Heisenbergrsquos principle is also applied to other pairs of quantities and this expresses the impossibility of measuring without error the quantum state of an object

All these difficulties in Star Trek are overcome by the prodigious

Heisenbergrsquos compensator

BUT

The science-fiction dream of projecting objects from one place to another is now a reality at least for

light particles photons

although it remains for now still a fantasy for macroscopic objects

It is a technique of communication within

Quantum Informatics ldquothis is a group of calculation methods and their study that use

the QUANTA to store and process informationrdquo

The technique of Quantum Teleportation allows under certain restrictions the

transfer of a quantum statesuch as the state of polarization of the photons the spin state of the

electrons or the excitation state of the atoms

to a point arbitrarily far

This involves the effect called

QUANTUM ENTANGLEMENT

QUANTUM TELEPORTATION Definition

QUANTUM TELEPORTATION Definition

It can be said that

by Quantum Teleportation there is not a transfer in the same way as in Star Trek but it is possible through the

phenomenon of entanglement

to transfer (instantly) featuresldquo (quantum states) of photons atoms ions

in other photons atoms ions placed at any distance

The quantum entanglement was suggested for the first time in 1926 by Erwin Schroumldinger who was also the first to introduce in 1935 the term entanglement

Quantum entanglement is a quantum phenomenon which has no classic equivalent According to this phenomenon each quantum state (eg polarization of the photons spin state of the electrons) of two or more physical systems depends on the state of each of them even if they are spatially separated

The quantum entanglement implies the presence of remote correlations between the observable physical quantities of the involved systems so that the non-local character of quantum theory is established

The phenomenon of entanglement therefore violates the principle of locality in which what happens in one place can NOT immediately affect what happens in another place

Albert Einstein despite the important contributions given to the quantum theory never accepted that a particle could instantaneously influence another particle Therefore he tried to prove that the violation of locality was only apparent but from time to time his attempts were clinched by his opponents

QUANTUM ENTANGLEMENT QUANTUM ENTANGLEMENT

In 1982 the physicist Alain Aspect with a series of sophisticated experiments demonstrated the existence of the entanglement and then the inconsistency of the

position of Einstein

In October 1998 the phenomenon of the entanglement was finally confirmed by the success of a teleportation

experiment performed by the Institute of Technology (Caltech) in Pasadena California

LEARN MORE ABOUT ldquoENTANGLEMENTrdquoLEARN MORE ABOUT ldquoENTANGLEMENTrdquo

If two particles interact for a certain period of time and then they are separated when one of them is stimulated so that it changes its state instantly a similar stress is manifested on the second particle whatever the distance between the particles in other words the second particle changes instantaneously its state

This phenomenon is called Phenomenon of Entanglement

A simple experiment about the Phenomenon of Entanglementrdquo

two particles ldquotwinsrdquo are launched in opposite directionsIf the particle 1 during its journey meets a magnet that deflects it upward the particle 2 instead of continuing its trajectory in a straight line deflects its direction at the same time assuming a motion contrary to that of the particle 1

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

BUT

The science-fiction dream of projecting objects from one place to another is now a reality at least for

light particles photons

although it remains for now still a fantasy for macroscopic objects

It is a technique of communication within

Quantum Informatics ldquothis is a group of calculation methods and their study that use

the QUANTA to store and process informationrdquo

The technique of Quantum Teleportation allows under certain restrictions the

transfer of a quantum statesuch as the state of polarization of the photons the spin state of the

electrons or the excitation state of the atoms

to a point arbitrarily far

This involves the effect called

QUANTUM ENTANGLEMENT

QUANTUM TELEPORTATION Definition

QUANTUM TELEPORTATION Definition

It can be said that

by Quantum Teleportation there is not a transfer in the same way as in Star Trek but it is possible through the

phenomenon of entanglement

to transfer (instantly) featuresldquo (quantum states) of photons atoms ions

in other photons atoms ions placed at any distance

The quantum entanglement was suggested for the first time in 1926 by Erwin Schroumldinger who was also the first to introduce in 1935 the term entanglement

Quantum entanglement is a quantum phenomenon which has no classic equivalent According to this phenomenon each quantum state (eg polarization of the photons spin state of the electrons) of two or more physical systems depends on the state of each of them even if they are spatially separated

The quantum entanglement implies the presence of remote correlations between the observable physical quantities of the involved systems so that the non-local character of quantum theory is established

The phenomenon of entanglement therefore violates the principle of locality in which what happens in one place can NOT immediately affect what happens in another place

Albert Einstein despite the important contributions given to the quantum theory never accepted that a particle could instantaneously influence another particle Therefore he tried to prove that the violation of locality was only apparent but from time to time his attempts were clinched by his opponents

QUANTUM ENTANGLEMENT QUANTUM ENTANGLEMENT

In 1982 the physicist Alain Aspect with a series of sophisticated experiments demonstrated the existence of the entanglement and then the inconsistency of the

position of Einstein

In October 1998 the phenomenon of the entanglement was finally confirmed by the success of a teleportation

experiment performed by the Institute of Technology (Caltech) in Pasadena California

LEARN MORE ABOUT ldquoENTANGLEMENTrdquoLEARN MORE ABOUT ldquoENTANGLEMENTrdquo

If two particles interact for a certain period of time and then they are separated when one of them is stimulated so that it changes its state instantly a similar stress is manifested on the second particle whatever the distance between the particles in other words the second particle changes instantaneously its state

This phenomenon is called Phenomenon of Entanglement

A simple experiment about the Phenomenon of Entanglementrdquo

two particles ldquotwinsrdquo are launched in opposite directionsIf the particle 1 during its journey meets a magnet that deflects it upward the particle 2 instead of continuing its trajectory in a straight line deflects its direction at the same time assuming a motion contrary to that of the particle 1

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

It is a technique of communication within

Quantum Informatics ldquothis is a group of calculation methods and their study that use

the QUANTA to store and process informationrdquo

The technique of Quantum Teleportation allows under certain restrictions the

transfer of a quantum statesuch as the state of polarization of the photons the spin state of the

electrons or the excitation state of the atoms

to a point arbitrarily far

This involves the effect called

QUANTUM ENTANGLEMENT

QUANTUM TELEPORTATION Definition

QUANTUM TELEPORTATION Definition

It can be said that

by Quantum Teleportation there is not a transfer in the same way as in Star Trek but it is possible through the

phenomenon of entanglement

to transfer (instantly) featuresldquo (quantum states) of photons atoms ions

in other photons atoms ions placed at any distance

The quantum entanglement was suggested for the first time in 1926 by Erwin Schroumldinger who was also the first to introduce in 1935 the term entanglement

Quantum entanglement is a quantum phenomenon which has no classic equivalent According to this phenomenon each quantum state (eg polarization of the photons spin state of the electrons) of two or more physical systems depends on the state of each of them even if they are spatially separated

The quantum entanglement implies the presence of remote correlations between the observable physical quantities of the involved systems so that the non-local character of quantum theory is established

The phenomenon of entanglement therefore violates the principle of locality in which what happens in one place can NOT immediately affect what happens in another place

Albert Einstein despite the important contributions given to the quantum theory never accepted that a particle could instantaneously influence another particle Therefore he tried to prove that the violation of locality was only apparent but from time to time his attempts were clinched by his opponents

QUANTUM ENTANGLEMENT QUANTUM ENTANGLEMENT

In 1982 the physicist Alain Aspect with a series of sophisticated experiments demonstrated the existence of the entanglement and then the inconsistency of the

position of Einstein

In October 1998 the phenomenon of the entanglement was finally confirmed by the success of a teleportation

experiment performed by the Institute of Technology (Caltech) in Pasadena California

LEARN MORE ABOUT ldquoENTANGLEMENTrdquoLEARN MORE ABOUT ldquoENTANGLEMENTrdquo

If two particles interact for a certain period of time and then they are separated when one of them is stimulated so that it changes its state instantly a similar stress is manifested on the second particle whatever the distance between the particles in other words the second particle changes instantaneously its state

This phenomenon is called Phenomenon of Entanglement

A simple experiment about the Phenomenon of Entanglementrdquo

two particles ldquotwinsrdquo are launched in opposite directionsIf the particle 1 during its journey meets a magnet that deflects it upward the particle 2 instead of continuing its trajectory in a straight line deflects its direction at the same time assuming a motion contrary to that of the particle 1

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

It can be said that

by Quantum Teleportation there is not a transfer in the same way as in Star Trek but it is possible through the

phenomenon of entanglement

to transfer (instantly) featuresldquo (quantum states) of photons atoms ions

in other photons atoms ions placed at any distance

The quantum entanglement was suggested for the first time in 1926 by Erwin Schroumldinger who was also the first to introduce in 1935 the term entanglement

Quantum entanglement is a quantum phenomenon which has no classic equivalent According to this phenomenon each quantum state (eg polarization of the photons spin state of the electrons) of two or more physical systems depends on the state of each of them even if they are spatially separated

The quantum entanglement implies the presence of remote correlations between the observable physical quantities of the involved systems so that the non-local character of quantum theory is established

The phenomenon of entanglement therefore violates the principle of locality in which what happens in one place can NOT immediately affect what happens in another place

Albert Einstein despite the important contributions given to the quantum theory never accepted that a particle could instantaneously influence another particle Therefore he tried to prove that the violation of locality was only apparent but from time to time his attempts were clinched by his opponents

QUANTUM ENTANGLEMENT QUANTUM ENTANGLEMENT

In 1982 the physicist Alain Aspect with a series of sophisticated experiments demonstrated the existence of the entanglement and then the inconsistency of the

position of Einstein

In October 1998 the phenomenon of the entanglement was finally confirmed by the success of a teleportation

experiment performed by the Institute of Technology (Caltech) in Pasadena California

LEARN MORE ABOUT ldquoENTANGLEMENTrdquoLEARN MORE ABOUT ldquoENTANGLEMENTrdquo

If two particles interact for a certain period of time and then they are separated when one of them is stimulated so that it changes its state instantly a similar stress is manifested on the second particle whatever the distance between the particles in other words the second particle changes instantaneously its state

This phenomenon is called Phenomenon of Entanglement

A simple experiment about the Phenomenon of Entanglementrdquo

two particles ldquotwinsrdquo are launched in opposite directionsIf the particle 1 during its journey meets a magnet that deflects it upward the particle 2 instead of continuing its trajectory in a straight line deflects its direction at the same time assuming a motion contrary to that of the particle 1

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

The quantum entanglement was suggested for the first time in 1926 by Erwin Schroumldinger who was also the first to introduce in 1935 the term entanglement

Quantum entanglement is a quantum phenomenon which has no classic equivalent According to this phenomenon each quantum state (eg polarization of the photons spin state of the electrons) of two or more physical systems depends on the state of each of them even if they are spatially separated

The quantum entanglement implies the presence of remote correlations between the observable physical quantities of the involved systems so that the non-local character of quantum theory is established

The phenomenon of entanglement therefore violates the principle of locality in which what happens in one place can NOT immediately affect what happens in another place

Albert Einstein despite the important contributions given to the quantum theory never accepted that a particle could instantaneously influence another particle Therefore he tried to prove that the violation of locality was only apparent but from time to time his attempts were clinched by his opponents

QUANTUM ENTANGLEMENT QUANTUM ENTANGLEMENT

In 1982 the physicist Alain Aspect with a series of sophisticated experiments demonstrated the existence of the entanglement and then the inconsistency of the

position of Einstein

In October 1998 the phenomenon of the entanglement was finally confirmed by the success of a teleportation

experiment performed by the Institute of Technology (Caltech) in Pasadena California

LEARN MORE ABOUT ldquoENTANGLEMENTrdquoLEARN MORE ABOUT ldquoENTANGLEMENTrdquo

If two particles interact for a certain period of time and then they are separated when one of them is stimulated so that it changes its state instantly a similar stress is manifested on the second particle whatever the distance between the particles in other words the second particle changes instantaneously its state

This phenomenon is called Phenomenon of Entanglement

A simple experiment about the Phenomenon of Entanglementrdquo

two particles ldquotwinsrdquo are launched in opposite directionsIf the particle 1 during its journey meets a magnet that deflects it upward the particle 2 instead of continuing its trajectory in a straight line deflects its direction at the same time assuming a motion contrary to that of the particle 1

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

In 1982 the physicist Alain Aspect with a series of sophisticated experiments demonstrated the existence of the entanglement and then the inconsistency of the

position of Einstein

In October 1998 the phenomenon of the entanglement was finally confirmed by the success of a teleportation

experiment performed by the Institute of Technology (Caltech) in Pasadena California

LEARN MORE ABOUT ldquoENTANGLEMENTrdquoLEARN MORE ABOUT ldquoENTANGLEMENTrdquo

If two particles interact for a certain period of time and then they are separated when one of them is stimulated so that it changes its state instantly a similar stress is manifested on the second particle whatever the distance between the particles in other words the second particle changes instantaneously its state

This phenomenon is called Phenomenon of Entanglement

A simple experiment about the Phenomenon of Entanglementrdquo

two particles ldquotwinsrdquo are launched in opposite directionsIf the particle 1 during its journey meets a magnet that deflects it upward the particle 2 instead of continuing its trajectory in a straight line deflects its direction at the same time assuming a motion contrary to that of the particle 1

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

LEARN MORE ABOUT ldquoENTANGLEMENTrdquoLEARN MORE ABOUT ldquoENTANGLEMENTrdquo

If two particles interact for a certain period of time and then they are separated when one of them is stimulated so that it changes its state instantly a similar stress is manifested on the second particle whatever the distance between the particles in other words the second particle changes instantaneously its state

This phenomenon is called Phenomenon of Entanglement

A simple experiment about the Phenomenon of Entanglementrdquo

two particles ldquotwinsrdquo are launched in opposite directionsIf the particle 1 during its journey meets a magnet that deflects it upward the particle 2 instead of continuing its trajectory in a straight line deflects its direction at the same time assuming a motion contrary to that of the particle 1

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

This experiment demonstrates that

1 the particles are able to communicate each other by transmitting and processing information

2 the communication is instantaneous

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

The physicist Niels Bohr said

Between two [related] particles that turn away from one another in space there is a form of

action - permanent communication []

Although two photons were located on two different galaxies they would still continue to

remain one entity

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

The experiments of Alain AspectThe experiments of Alain Aspect

In 1982 Alain Aspect with the collaboration of the researchers J Dalibard and G Roger of the Optic Institute of the University of Paris demonstrated the existence of the entanglement thus confirming the hypothesis of non ndash localityrdquo of the quantum theory

The figure shows a simplified scheme of the equipment used by Aspect and his collaborators during the experiments

An excited atom of calcium at the center of the figure produces a pair of entangled photons that move along opposite paths ldquoA and Brdquo

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

Along the path Aldquo a birefringent crystal that acts as a filter is inserted from time to time When the photon interacts with the crystal it can be deflected with a probability of 50 or it can cross the crystal continuing undisturbed on its way At the end of each path a photon detector is placed that allows the detection of the photons

The amazing thing that Aspect observed was that

when along the path A the birefringent crystal was inserted and a deviation of the photon 1 occurred to the detector C on the path B also the photon 2 (photon separate and without obstacles in front) deflected spontaneously and ldquoinstantlyrdquo toward the detector D Basically the act of introducing the birefringent crystal with the consequent deviation of the photon 1 made instantly and remotely deflect the photon 2

This might sound strange but thats what actually happens when experiments on pairs of entangled particles are made

So the idea that entangled particles located in distant places represent separate entities must be abandoned

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

In reference to the uniqueness of the matter that stems from the ldquonon localistrdquo vision of quantum theory Brian Josephson (the Nobel Prize for Physics) says

The universe is not a collection of objects but an inseparable network of vibrating energy patterns in which no

single component has independent reality

including the observer

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

SCHEMATIC REPRESENTATION OF A QUANTUM TELEPORTATION PROCESS

Receiving station R

Source of entangled photons

Source EPR

Source of entangled photons

Source EPR

Transmitted photon

Transmitting station T

C

C

A B

A

Photon to be transmitted

Entangled photons

C B

Entanglement is frequently called ldquoEPR effect from the initials of Albert Einstein Boris Podolski and Nathan Rosen They in 1935 analyzed the consequences of particles placed at great distances The involved particles are called EPR pairsrdquo

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

1 Production of a pair of entangled photons A e B by an appropriate device

2 Sending of the entangled photons A e B respectively to the transmitting station T and to the receiving station R

3 Sending of the photon C of which you want to teleport the state of polarization to the transmitting station T

4 Interaction at the start station T between the photons A and C and measure on the combined system

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

SHORT DESCRIPTION OF THE QUANTUM TELEPORTATION PROCESS

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

6 Communication to the R station by the traditional media (eg telephone call) of the result of the measurement on the photon A and the photon C (4 results are possible)

7 Change of the status of photon B based on the information communicated

RESULTQuantum teleportation of the photon C this means that

a photon with the same polarization state of the photon C has been obtained without any measurement on it

5 Simultaneous change during the measurement of the polarization state of the photon B at the R station

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

Amanda and Bert intend to teleport the photon C Amanda is at the T station and Bert is at the R station

At the beginning each receives one photon of an entangled pair Amanda receives the photon A and Bert receives the photon B Instead of carrying out a measure on the photons they keep their photon without disturbing the entangled state

Amanda receives a third photon C that she wants to teleport to Bert Amanda in practice without knowing the polarization state of the photon C wants that Bert has a photon with the same polarization of the photon C

It is important to notice that Amanda cannot simply measure the polarization state of the photon C and then communicate the result to Bert because for the uncertainty principle the measure couldnt accurately reproduce the original state of the photon

To teleport the photon C Amanda makes A and C to interact and performs a measurement on the system without determining in absolute terms the individual polarizations of the two photons The measurement can give 1 of 4 possible results

More detailed description of the Quantum Teleportation process

More detailed description of the Quantum Teleportation process

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

To complete the teleportation Amanda has to send a message to Bert by the conventional methods (a phone call or a written note) After receiving this message Bert if necessary may transform his photon B in order to make an exact replica of the original photon C The transformation that Bert should apply depends on the result of the measurement of Amanda

Which of the four possible results Amanda gets is due to chance Therefore Bert does not know how to modify his photon until he receives from Amanda the result of the measurement

After this transformation Berts photon is in the same state of the photon C

In technical terms a joint measurement of this type is called ldquoBells state measurementrdquo and it has a particular effect

It induces instantly a change in Berts photon correlating it to the result of the measurement performed by Amanda and to the state that the photon C originally had

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

Its important to observe that

the measurement that Amanda made connects the photon A to the photon C So the photon C loses all the memory of its original state Therefore the original state of the C photon after the measurement disappears from the place where Amanda is

The result of the measurement of Amanda being totally random doesnt say anything about the quantum state In this way the process bypasses the Heisenbergrsquos principle which doesnt allow full determination of the state of a particle but allows the teleport of the state provided that Amanda doesnt try to know what it is

The state of the C photon has been transferred without Amanda and Bert had any knowledge of it

Then what has been transported is not the photon but its polarization state or generally its quantum state However since quantum state is a peculiar characteristic of a particle we can say that to teleport a quantum state is like teleport the particle

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

In one of the four cases the measurement of Amanda is lucky and Berts photon becomes immediately a replica of the originalIn this case it might seem that the information travels instantly from Amanda to Bert breaking the limit imposed by Einstein It is not so in fact Bert has no way of knowing that his photon is already a replica of the original Only when he learns the result of the measurement of the Bells state performed by Amanda and transmitted to him by the classical information he can take advantage of the information about the teleported quantum state

In addition the teleported quantum information doesnt travel physically What is transferred essentially is just the message on the result of the measurement of Amanda that says to Bert how he has to modify his photon without any indication on the state of the C photon

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

We are still far from the teleportation of a large object The main problems are

two entangled objects of the same type are requiredthe object that should be teleported and the entangled objects must be

sufficiently isolated from the environmentIf any information is exchanged with the environment through accidental interaction the quantum state of the object degrades in a process called decoherence It is hard to imagine how you can achieve this absolute isolation for a body of macroscopic dimensions and even more for a human being because he breathes air and exchanges heat with the outside world But who can predict the future developments Of course we could use existing technology in order to teleport elementary states such as those of the photons over distances of few kilometers and perhaps even up to the satellites

CONCLUSIONSCONCLUSIONS

What will happen afterwards nobody knowsWhat will happen afterwards nobody knows

The technology that can teleport states of individual atoms has been reached as shown by the group led by Serge Haroche of the Ecole Normale Supeacuterieure in Paris which has produced entangled atoms

Entangled molecules and their teleportation can be reasonably expected within the next decade

back to the table of contents

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

The first quantum teleportation experiments were carried out between 1993 and 1997 by two international research groups led respectively by Francesco De Martini from La Sapienza University in Rome and Anton Zeilinger from the Institute of Experimental Physics in Vienna They were able to teleport the quantum state of a photon

Quantum Teleportation from 1997 to today

Quantum Teleportation from 1997 to today

In 2004De Martini carried out a teleportation of photons from

one part to another of the Danube covering a distance of 600 meters

two groups of scientists one from the National Institute of Standards and Technology in the United States and one from the University of Innsbruck in Austria were able to teleport some of the properties of atoms for the first time The Americans worked with beryllium atoms while the Austrians with calcium atoms

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

some researchers from Niels Bohr Institute in Copenhagen teleported a collective state from a group of about a trillion of atoms to another The Teleportation applied to the atoms ie to the matter is a very delicate process compared to that made on the photons due to the process of decoherence This process due to interactions with the environment destroys the quantum effects including entanglement

In 2006

In 2010 in China the researchers of the Hefei National Laboratory for Physical Sciences reached 16km in the teleportation of photons without the support of optical fibers

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

a group of researchers succeeded in realizing the quantum teleportation of the information relating to a complicated system of about 100 million of rubidium atoms that had a magnitude of about one millimeter The study was conducted by Jian-Wei Pan of the Hefei National Laboratory for Physical Sciences at the Microscale with the collaboration of the researchers of the University of Science and Technology in China and of the University of Heidelberg

For the teleportation scientists prepared in laboratory an entangled pair of granules of rubidium Entangled granules were placed at the distance of about half a meter and then the two systems were connected by an optical fiber 150 meters long and rolled up on itselfBefore performing the process of quantum teleportation the scientists mapped the state of excitation of the rubidium atoms in a photon that traveled along the optical fiber It was possible to realize the teleportation by the interaction between the photon messenger with another photon and with the second system of atoms

In 2012

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

The team of researchers from the University of Science and Technology of China in Shanghai was able to teleport more than 1100 photons in 4 hours covering a distance of 97km of free space establishing a new record and overcoming the distance of 16km obtained from the previous experiment in 2010

The research team of the Optical Ground Station of the European Space Agency (ESA) in the Canary Islands settled down a new world record on the distance about the quantum teleportation reproducing the characteristics of a light particle to a distance of 143km (between Jacobus Kapteyn Telescope La Palma and ESAs Tenerife Train optical)

In 2012

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

A group of physicists from the research center Quantop at the Niels Bohr Institute of the University of Copenhagen has teleported informations between two clouds of gas atoms of cesium far from each other half a meterThe physicists have used two glass containers that were not connected and the teleportation of the information from one cloud to another occurred by means of laser light

In 2013

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

It is expected that the next teleportation

experiment will consist of a

Quantum Teleportation between the

Earth and a Satellite in Earth orbit

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

Applications of the Quantum Teleportation

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Realization of quantum computers and networks extremely powerful and faster than the actual classical computers and networks

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Exchange of information 100 secureIn fact between the sending station and the receiving station only one classic signal is exchanged this doesnt allow to a person who intercepts the classic signal to know the information in the form of quantum state that you are teleporting

Dream of teleportation as in Star TrekDream of teleportation as in Star Trek

back to the introduction

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

QUBITS AND QUANTUM COMPUTERS QUBITS AND QUANTUM COMPUTERS

QUBIT or quantum bit (quantum binary digit) is

the unit of quantum information

BIT (binary digit) is

the unit of classical information

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

The classical bits operate on binary code and can encode only one value at a time 0 or 1

The qubits process the information following the laws of quantum mechanics and the principle of quantum superposition ie the idea that an object can exist in multiple states at the same time they can take at the same time the state 0 and 1

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

In a classical system one bit of information can be represented for example by the voltage applied to the plates of a capacitor the charged capacitor denotes the bit 1 and the not charged capacitor denotes the bit 0

Quantistically one bit of information can be encoded using a two-level system such as the spin states of an electron the two polarizations of the light

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

What is a quantum computerWhat is a quantum computer

The conditions for the realization of quantum computers and quantum networks able to offer the best performance in power and speed of calculation are provided by the

QUANTUM TELEPORTATION

the phenomenon of teleportation of qubits achieved by the quantum phenomenon of entanglement

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

In a quantum computer the information would be recorded in qubits instead of stored in

bits as in a classical computer

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

How much information can be contained in a QUBIT

Therefore a quantum computer does not have advantages compared to the classical computer at least for what concerns the amount of information stored

The advantage of a quantum computer instead consists of an exponential increase in computing capability

In practice a Qubit cannot contain more information than a classical bit because it assumes the value 0 or 1 when the information is processed

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

A quantum processor that can operate on N Qubits has the computing power of a classical processor that operates

on 2N bits

Quantum computers are able to manage in a few minutes

lots of data

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

At the present several proposals are under consideration to build a quantum computer (nuclear magnetic resonance ion traps optical systems superconducting circuits etc) but currently it is not clear which way is the most likely to succeed

There are many technological difficulties to be overcome to realize a quantum computer One of these is the

decoherence

In other words the inevitable interaction with the external environment would destroy in a short time the quantum coherence that is the information contained in the quantum computer

TECHNOLOGICAL DIFFICULTIES

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing

Learn more about

The roots of entanglementhttpwwwscienzaeconoscenzaitarticolole-radici-dell-039-

entanglementphp

The quantum non-separability httpwwwscienzaeconoscenzaitarticolola-non-separabilita-

quantisticaphp

back to the introduction

European Space Agency (ESA)httpwwwesaintesasearchq=quantum+teleportation

Quantum bits and Quantum Computers

httpphysorgtagsquantum+bits

httpphysorgtagsquantum+computing