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F r o m Q u a n t u m S c i e n c e t o Q u a n t u m Te c h n o l o g i e s
Raymond Laflamme [email protected]
www.iqc.ca
Message
-Quantum Information Science has taught us the right language in order to be able to talk and be talked to by quantum systems (atoms, molecules etc..)
-From that knowledge we are learning of taking advantage of the quantum world and although quantum computers are still some time in the future, the impact of quantum sensors has already started to happen.
The Quantum World
“a place where there are no penalties for interference” Miriam Diamond, USEQIP student Undergraduate Summer Experimental Quantum Information Program https://uwaterloo.ca/institute-for-quantum-computing/programs/useqip
Cycle of Discoveries
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Successes of Quantum Information Science
• Discovery of the power of quantummechanics for information processing
-new language forquantum mechanics
• Discovery of how to control quantum systems• Proof-of-concepts experiments
Successes of Quantum Information Science
• Discovery of the power of quantummechanics for information processing
-new language forquantum mechanics
• Discovery of how to control quantum systems• Proof-of-concepts experiments
Plus !! Development of practical quantum information technologies
On the first floor …
Mik
e an
d O
pehl
ia L
azar
idis
Qua
tnum
Nan
o C
ente
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nive
rsity
of W
ater
loo
Quantum Technologies today Made possible because the world in quantum
Lasers LEDs
MRI Transistors
Quantum Information: The QUBIT
Quantum Dots
Spin-based QIP Superconducting Qubits
Quantum Optics
Trapped Ions
Trapped Atoms
Quantum Sensors
Harnessing the quantum world will allows us to achieve:
•! Greatest precision
•! Greatest sensitivity
•! Greatest selectivity
•! Greatest robustness
•! Greatest efficiency
Quantum Information provides the right language and tools
NMR quantum computing
Brief history of NMR Bloch and Purcell
Applications of NMR -MRI -molecular structure -chemical analysis -concrete research -tire compositions - molecular dynamics -…
H
C
Cl
ClCl
C
13
13
1
2
Trichloroethylene
010=| >N S
NMR quantum computing
Brief history of QIP achievements •! laboratory feedback on quantum control •! theoretical challenges: DQC1
•! development of experimental QECorrection •! … -push the quality of quantum control
Cl
Cl
C1
C2
C4C5
C6 C7
C3
H
H4
H2
H3
H1
H5
OO
O
S
12(I + αZ)
I⊗n
2n
John Waugh
Challenge with inhomogeneity
B+!B B-!B B
"#
"B+!B > "B > "B-!B
A rf inhomogeniety selective pulse
-1 1 2 3
0.2
0.4
0.6
0.8
1
rf inhomogeneity
# of
spin
s
3.0% 4.5% 6.0% 7.5%
0.2
0.4
1.0
0.6
0.8
1.5%
rf inhomogeneity
am
ount
of s
igna
l
xy
z
0
1
XY
Z
!!
""
Find a pulse sequence that keep the spins that are within a given homogenity bound and spread the other around the sphere
NMR Oil well logging
Application to oil well logging by measuring presence of •! water/oil •! porosity of rocks •! motion of the liquid MRIL® Magnetic Resonance Imaging Logging
Direct Measurements Produce Better Results
The proof is in the logs. Halliburton's Magnetic Resonance Imaging Logging (MRIL®) is revolutionizing the openhole logging business through direct measurement of reservoir fluids, such as oil, gas, and water. Now, operators can identify water-free production zones and previously hidden pay zones in their wells using MRIL technology. Increasing reserves by providing a complete, accurate analysis of a low resistivity/low contrast interval Identifying commercial zones in a laminated, fine-grained sand and shale formation Improving completion success in a low permeability reservoir Establishing water-free oil production in a low resistivity zone …
Small pore
Am
plitu
deTime, msec
Large pore
Am
plitu
de
Time, msec
http://www.halliburton.com
Measuring a magnetic field
φ(t, τ ) =1
�
∫ t+τ/2
t−τ/2µB(t′)dt′
0
1
XY
Z
!!
""
x
y
z
x
y
z
x
y
z
x
y
z
x
y
z
x
y
z
precession
(t- /2,t)�
precession
(t,t+ /2)�
�spin-echo �spin-echo
N S
5 10 15 20 25 30
-1
-0.5
0.5
1Cos[ ]
Ψ(φ(t, τ )) = |0〉 + eiφ(t,τ )|1〉
Prob(|0〉〈0|) = Cos[φ(t, τ )]
Technology comparison
MRFM (2004)
Atom chip (2005)
MRFM (2007)
SQUIDS (2008) MRFM (2009)
1!m 10nm
10-8 10-6 10-4 10-2 100
Distance [m]
Superconducting qubits as sensors
History of superconducting (qu)bits
•! long experience (> 50 year) of behavior at classical level. •! versatile and easily tunable •! (hopefully) relatively easily scalable
•! one of the first quantum use: test quantum mechanics
Superconducting qubits as sensors
Superconducting qubit: mesoscopic system that using superconducting material to build ``artificial atoms’’ C=capacitance
L=inductance Q=charge on the capacitance $=flux through the loop
E =L
2
dQ
dt
2
+1
2CQ2 =
1
2LΦ2 +
1
2CQ2
X or
Potential Energy
E=h
E=h
E=hx /22
E =1
2p2 +
1
2(q − Λ)2
Λ is the control parametercharge qubit Λ = Vg← gate voltagephase qubit Λ = I ← bias currentflux qubit Λ = Φext ← external flux
Superconducting qubits as sensors
Superconducting qubits: mesoscopic system that using superconducting material to build artificial atoms”
Need to make energy level different: do this by adding a Josephson junction
E =1
2LΦ2 +
1
2CQ2
-10 -5 5 10
20
40
60
80
100
+ Ej cos(2πΦ/Φ0)
Josephson junction
a)
b)
Superconducting Qubits: A Short Review M. H. Devorety, A. Wallray, and J. M. Martinis
Superconducting Circuits for Quantum Information: An Outlook M. H. Devoret and R. J. Schoelkopf, Science 339, 1169 (2013);
Sensitivity vs resolution for our detector
Lupascu’s quantum sensor Nature Communications, 3, 1324 (2012), preprint arXiv: 1301.0778.
DARPA compilation (QUASAR)
sensitivity of 3.3 pT Hz1/2 for a frequency of 10 MHz.
Can we do better?
NV centers
!
!
!
Energy diagram
N
V
Scientific American, October 2007
NV centers
Explain how they work and the achievement of Yacoby
a
MW coil Sensor NV
Target spins
Scanning diamond platform
Excitation laser
MW
2 B
z
yx
|1〉
|–1〉
ω
|0〉
γ
Yacoby, Nature Physics 9, 215, 2013
50 nanometer above target
Measure single spin “long coherence time” -room temperature -can initialized the qubit -measure electron spin resonance
Electron spins: -> electronic resolution: 2.7 Å Nuclear spins: -> nuclear resolution: 6 Å
Neutron interferometry
Collaboration of IQC, NIST and Brockhouse Institute
Interesting use of neutron interferometers: non-destructive measurement at the atomic scale: characterize magnetic, nuclear, and structural properties of materials, protein structure, can be use on biological or cold material, fundamental studies in physics, information science and solid-state physics
Quantum sensors
Dima Pushin D. A. Pushin,M. G. Huber, M. Arif,and D. G. Cory PRL 107, 150401
Neutron interferometry
Quantum sensors
-but the interferometer is fragile -neutron characteristics
velocity about 1000m/s wavelength is about ~0.2 nm i.e. a few angstrom
Dominant noise mode
Quantum Error Correction
Probability of success per gate: P ~(1 %) Probability of success for n gates Pn~(1 e)n: i.e.exponential decrease
Classical error correction thought to require:
•! discrete errors (bit flips.. does not work for analog devices) •! copying information (but no cloning theorem) •! measure the bits (destroy coherence)
A simple family of code:
Decoherence free subspaces:
They are subspaces that are not affected by noise
e.g. this state is invariant wrt rotations
this state is not invariant
| ↑↓〉 − | ↓↑〉 | ↑↓〉 + | ↓↑〉
Neutron interferometry
an example of macroscopic quantum coherence
IO = "O2 = t 2 r 4 1+ cos #( )[ ]
Measure the neutron
Intensity.
In this case that is the
number of neutrons
per unit time.
IH = "H2 = r 2 t 4 + r 4( )# r 2 t 2 cos $( )[ ]
Neutron interferometry
an example of macroscopic quantum coherence
Measure the neutron
Intensity.
In this case that is the
number of neutrons
per unit time.
|0>
|1>
1
1 1
1
2
2 2
2
3
3
4
4
1 1
2
2 2
2 3
4
4
|0>
|1>
|00>
|01>
|10>
|11>
3
1 1
1 1
2 2 3
4
4
|0>
|1>
|01>
|10>
3
Neutron interferometry
The 4/5 blade interferometer robust again rotation
beam blocks
neut
ron
bea
m
phase flag
perfect
Si sing
le cryst
al interf
erome
ter
O-b
eam
H-beambeam blocks
neutron
detectors
(220)
+
neutron
beam
interferometer
enclosuremotor
off
-ce
nte
r m
ass
a b
c
low frequency vibration isolation table
vibration
isolation pads
vibration
isolation pads
650
600
550
500
450
Ne
utr
on
s p
er
30
0 s
ec
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Phase flag rotation, (°)
No vibration
8 Hz vibration3 blade
700
650
600
550
500
450
400
350
Ne
utr
on
s p
er
30
0 s
ec
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Phase flag rotation, (°)
No vibration
8 Hz vibration
4 blade
a
b
S/N ratio increased by 600
GEO600: gravitational wave detector
Use Michaelson interferometer to precisely measure distance
GEO600: gravitatinal wave detector
Use Michaelson interferometer to precisely measure distance
vacuum
The Vacuum in Quantum Mechanics
Uncertainty relations
X or
Potential Energy
E=h
E=h
E=hx /22
X P
∆X × ∆P ≥ �/2
X P
Ground state
Squeezed Ground state
GEO600: gravitational wave detector
H. Grote,* K. Danzmann, K. L. Dooley, R. Schnabel, J. Slutsky, and H. Vahlbruch Max-Planck-Institut fu¨r Gravitationsphysik (Albert Einstein Institut) und Leibniz Universita¨ t Hannover, Callinstraße 38, 30167 Hannover, Germany
Squeezed vacuum +15.2MHz subcarrier field
Injection lockedhigh-power
laser system
2 sequentialmode-cleaners(8m round-trip)
MPRT=0.09%
MSRT=10%
600m north arm(folded in vertical plane)
600m east arm(folded in vertical plane)
BSMCe
MFe
Faraday Isolator
OMC
MCn
MFn
Dataoutput
h(t)
Michelson output signal +14.9MHz sidebandsPhase locked loop
1064nm
SqueezedLight Source
1064nm
vacuum system =
photo diode =
PDallignment
2 axis piezoactuated mirror
Squeezing phasefeedback
Bandpass andRMS estimation
3.6-5.4 kHz
11.6 Hz15.2 MHzvoltage controlled
phase shifter
mirror =
generic electronics =
electronic oscillator =
electronic mixer =
φ
G 1 ( l li ) A i lifi d i l l f h d li h h d i i l d G O 600 hi h
102
103
10−22
10−21
10−20
Frequency [Hz]
Str
ain
[1/
√Hz]
No SqueezingSqueezing
−0.5 0 0.5 1 1.5 2 2.5 3 3.5 40
1
2
3
4
5
6
7
8
9
10
Tim
e [d
ays]
Squeezing [dB]
No squeezing
Squeezing
PRL 110, 181101 (2013) P HY S I CA L R EV I EW LE T T E R Sweek ending3 MAY 2013
Summary
Quantum Information Science has made much progress and although a practical quantum computers are still in some distance away (possibly 100 qubits in the next 5 years) there has been spin-off technology that has made it to the market. It is the start of seeing useful quantum information technologies. This is the beginning of the quantum technological era.
Thank you
www.iqc.ca
