фото

MANIPULATING THE QUANTUM STATE

OF SINGLE ATOMS AND PHOTONS

works of Nobel Laureates in physics 2012

A.V.Masalov

Lebedev Physics Institute, RAS, Moscow

masalov@sci.lebedev.ru

Nobel Prize in Physics 2012:

Serge HAROCHE and David J. WINELAND

"FOR GROUND-BREAKING EXPERIMENTAL METHODS

THAT ENABLE MEASURING AND MANIPULATION

OF INDIVIDUAL QUANTUM SYSTEMS“

PHOTONS IONS

Serge HAROCHEÉcole Normale Supérieure, Paris, France

MANIPULATING THE QUANTUM STATE

OF SINGLE PHOTONS

INDIVIDUAL QUANTUM SYSTEMS:

photons of electromagnetic field @ 51.1 ГГц ( ~ 6 mm); number of photons – from 1 to about 10.

MEASURING AND MANIPULATION:

by means of single atoms in superpositional states.

SUPERCONDUCTING CAVITIES:

- Open Fabry Perot

- Niobium on diamond machined copper

- Unprecedented lifetime @ 51 GHz, 0.8 K :

Tc = 0,13 s

Q = 4,2 × 1010

F = 4,6 × 109

!!! Average number of thermalphotons ~ 0.05

CIRCULAR RYDBERG ATOMS:

- Long lifetime (30 ms)

- Millimeter-wave transitions

- Tunable via the Stark effect

- Large coupling to radiation

- Efficient and state-selective

single-atom detection

!!! Excitation to superpositional

states (by ‘’-pulse of light):

g e

n = 0

n = 1

n = 2n = 3

B – atomic source (beam of single Rb atoms) selected by velositiy:

~ 900 pc/s, ~ 250 m/s.

С – superconducting resonator: 51.1 GHz, 0.8 K, tunable (!)

R1 и R2 – auxilary resonator for excitation anf analysis of atoms.

S – source of radiation at about 51 GHz.

D – detector of atomic state: or .eg

Source R1 ‘’-pulse atom g e

Main resonator C tuned close but out of resonance with atoms

Atoms are exposed to Stark-shift of levels in the interaction area C:

Atom + 1 photon: ig e e g e

Source R2 ‘’-pulse atom + 1 photon 1 pure exited state!ie

atom + 0 photon 0 pure ground state!

INTERFEROMETER RAMSEY

SINGLE PHOTON IN RESONATOR

Photon decay in resonator:

1 realization

5 realizations

15 realizations

904 realizations

INTERFEROMETER RAMSEY

The ‘door’ from classical world to quantum one:‘’-pulse

g e

The ‘door’ from quantum world to classical one:interferometer Ramsey g e

e

g

More delicate coding of photon numbers in resonatorby phase in superpositional state of atoms

Number of photons

Atomic state Atomic state out of

Ramsey interferometer

0

1

2

3

4

5

6

7

00 ig e e 10 ig e e

20 ig e e 30 ig e e 40 ig e e

50 ig e e 60 ig e e 70 ig e e

2 /8

sin6 cos6g e

0 1g e

sin cosg e

sin 2 cos2g e

sin3 cos3g e

sin 4 cos4g e

sin5 cos5g e

sin7 cos7g e

More delicate coding of photon numbers in Cby phase in superpositional state of atoms

1. Photon-state preparation in C by resonant atoms.2. Photon-state detection by non-resonant atoms:

QUANTUM NON-DEMOLITION MEASUREMENTS OF PHOTON NUMBER IN RESONATOR

POISSON DISTRIBUTION OF PHOTONS(at final stage on measurements)

TRACING THE NUMBER OF PHOTONS IN RESONATOR

Homodyning the quantum state of photons

Reconstruction of density-matrix and quasiprobability distributionof radiation with n = 1

Reconstruction of density-matrix and quasiprobability distributionof radiation with n = 2

Reconstruction of density-matrix and quasiprobability distributionof radiation with n = 3

Reconstruction of density-matrix and quasiprobability distributionof radiation with n = 4

even odd decoherence

Reconstruction of density-matrix and quasiprobability distributionof radiation in the states of ‘Schredinger-cat’

END

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