QuantumInformation
FundamentalQuantumPhysics
QNDmeasurements
Cavity
QEDExperimentatLKBS.Haroche,J.M.Raimond
Complementarity
Outline
Aimandordersofmagnitude
Apparatus
RabiOscillations
RamseyInterferometry
Conclusion
Interaction:lightfield↔atom
Strongcouplingregime:
JaynesCummingsmodel
Howtoaccessthestrongcouplingregime
Groundstateτ=100ns
Γ~10MHz
Rydbergstateτ=30msΓ~30Hz
Optical300THz
0.1- 1μmκ~MHz
g=3GHzg/Γ=300
g/ϰ=300
g=400MHz
Microwaves51GHz
6cmκ~10Hz
g=3kHz g=200kHzg/Γ=60000
g/ϰ=20000
Howtoaccessthestrongcouplingregime
Groundstate RydbergAtoms
g=400MHz
g=200kHzg/Γ=60000
g/ϰ=20000
Circularstate:
● maximuml,m
● most“classical”state
● longlifetime
● verygood2-level-system(in
directingel.field)
→uniquedecaychannel
● “sensitiveandselectivedetection”
Overviewofthesetup LaboratoireKastler
Brossel,
Paris
Stepbystep
87Rbthermalbeam
Velocity(Doppler)selectiveexcitation
SuperconductingFabry-Pérotcavity
shiftablemirrors
VoltageforStarkshift
State-selectivefieldionization
ClassicalmicrowavesourceRamseyinterferometer:2lowQcavites
Classicalmicrowavesource
CircularStatePreparation
2)
1)
RFLaser
(n,l,m)=(50,49,49)
Stepbystep
87Rbthermalbeam
Velocity(Doppler)selectiveexcitation
SuperconductingFabry-Pérotcavity
shiftablemirrors
VoltageforStarkshift
State-selectivefieldionization
ClassicalmicrowavesourceRamseyinterferometer:2lowQcavites
Classicalmicrowavesource
● Diameter50mm● Curvature40mm
● Length27mm
9antinodes
SuperconductingHighlypolished
Niobiummirrors
Cryostat→0.8K
LiquidNitrogen
LiquidHelium-4
Liquid
Helium-3
SuperconductingFabry-PérotCavity
Stepbystep
87Rbthermalbeam
Velocity(Doppler)selectiveexcitation
SuperconductingFabry-Pérotcavity
shiftablemirrors
VoltageforStarkshift
State-selectivefieldionization
ClassicalmicrowavesourceRamseyinterferometer:2lowQcavites
Classicalmicrowavesource
Detection
• Electricfieldionizesatoms
dependingontheirmainquantum
numbern
• adjustable
• circularstatepurity98%
• Upto80%detectionefficiency
90%fidelityafterselection
Stateevolution
Ramsey Interferometry
Microwave field (51 GHz)
Ramsey Interferometry
Microwave field (51 GHz)
Ramsey InterferometryAcquired phase shift
Transition probability
Ramsey Interferometry
Quantum Non-Demolition measurement of light
• count photons without destruction
• 1. Ramsey zone: !/2 pulse → superposition
• Cavity: phase shift
• 2. Ramsey zone: !/2 pulse →photon number
Rabi Oscillations
Rabi Oscillations
Rabi Oscillations
Coherent field
Large number of photons: Collapse and Revival
Coherent state:
Coherent state
Photon number <n>
Prob
abilit
y
So what?Where are the difficulties?
Problems to solve
• Quality/finesse of cavity
• Decoherence time
• Control Rydberg states
• Strong Coupling
• Screen room-temperature blackbody field
• Selection mechanism for velocity
References
J.M.Raimond,M.BruneandS.Haroche,Manipulating quantumentanglement withatomsandphotonsinacavityRev.Mod.Phys.73,565
T.F.Gallagher.Rydbergatoms.CambridgeUniversityPress,1994
B.Peaudecerf,C.Sayrin,X.Zhou,T.Rybarczyk,S.Gleyzes, I.Dotsenko, J.M.Raimond,M.Brune,andS.Haroche,Quantumfeedbackexperiments stabilizing Fockstatesoflight inacavity,Phys.Rev.A87,042320
C.Sayrin,I.Dotsenko,X.Zhou,B.Peaudecerf,T.Rybarczyk,S.Gleyzes,P.Rouchon,M.Mirrahimi,H.Amini,M.Brune,J-M.
Raimond&S.Haroche,Real-timequantum feedbackpreparesandstabilizesphoton numberstates,Nature,477,73(2011)
X.Zhou,I.Dotsenko,B.Peaudecerf,T.Rybarczyk,C.Sayrin,S.Gleyzes, J.M.Raimond,M.Brune,andS.Haroche,FieldLocked toaFockStatebyQuantumFeedback withSinglePhotonCorrections ,Phys.Rev.Lett.108(2012)
http://www.cqed.org,[Online],April2016
S.Haroche, J.M.Raimond.Exploring theQuantum.OxfordUniversityPress,2006
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