Controlling photons in a box and exploring the quantum to classical ...
Controlling photons in a box and exploring the quantum to classical ...
Controlling photons in a box and exploring the quantum to classical ...
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<strong>Controll<strong>in</strong>g</strong> <strong>pho<strong>to</strong>ns</strong> <strong>in</strong> a <strong>box</strong> <strong>and</strong>explor<strong>in</strong>g <strong>the</strong> <strong>quantum</strong> <strong>to</strong> <strong>classical</strong>boundarySerge Haroche…
How ‘’thought experiments’’ controll<strong>in</strong>g azoo of particles became realNew <strong>quantum</strong> technologies:Tunable lasersFast computersSuperconduct<strong>in</strong>gmaterials
«Particle control <strong>in</strong> a <strong>quantum</strong> world»(«!<strong>in</strong> vivo!» physics)BoulderParisTwo sides of <strong>the</strong> same co<strong>in</strong>:manipulat<strong>in</strong>g non destructivelys<strong>in</strong>gle a<strong>to</strong>m with <strong>pho<strong>to</strong>ns</strong> or s<strong>in</strong>gle pho<strong>to</strong>n with a<strong>to</strong>msTrapped<strong>pho<strong>to</strong>ns</strong>(CQED):Brune et al,PRL, 76, 1800(1996)Trapped ions:Meekhof et al,PRL, 76, 1796(1996).
Boboli Gardens, Florence (August 1996)
PhD with Claude Cohen-Tannoudji (1967-71)Optical pump<strong>in</strong>g experiments &Dressed a<strong>to</strong>m formalism1997Postdoc with Arthur Schawlow (1972-73)(1921-1999)1981Quantum beats excited by dye lasers(time evolution ofstate superpositions)
…but <strong>the</strong> s<strong>to</strong>ry really started with <strong>the</strong> firststudies of Rydberg a<strong>to</strong>m masers <strong>in</strong> <strong>the</strong> late1970’sM. Gross, C. Fabre, S. Haroche, J.M. Raimond, PRL 43, 343 (79)Cavity on resonanceCavity off resonanceOpencavityAn <strong>in</strong>sightfulcomment…<strong>and</strong> <strong>the</strong>beg<strong>in</strong>n<strong>in</strong>g ofCavity QuantumElectrodynamics
With Michel Gross <strong>and</strong> Claude Fabre (1977?)Philippe Goy <strong>and</strong> his microwave equipment(1978?)With YvesKaluzny,Claude Fabre <strong>and</strong>Jean-MichelRaimond (1980?)
The Micromaser (1984)H.Wal<strong>the</strong>r(1935-2006)The regime of a<strong>to</strong>m-pho<strong>to</strong>n<strong>quantum</strong> mechanical oscillation(«!strong coupl<strong>in</strong>g regime!» ofCavity QED) was achieved first<strong>in</strong> <strong>the</strong> cw micromaserD.Meschede(<strong>in</strong> 1987)A cyl<strong>in</strong>drical cavity with a very long pho<strong>to</strong>nlife-time…but a<strong>to</strong>mic superpositions areperturbed by pass<strong>in</strong>g through small holes
Pho<strong>to</strong>n detection by pho<strong>to</strong>electric effect:«!chronicle of a fore<strong>to</strong>ld death!»«clic»«clic» «clic»1 !!"0 A clic projects <strong>the</strong> field on<strong>to</strong> <strong>the</strong> vacuum:clic<strong>the</strong> pho<strong>to</strong>n dies upon deliver<strong>in</strong>g its messageA Quantum Non-Demolition (QND) measurement should <strong>in</strong>stead realize: 1!!"1 !!"1 !!" !clicclicclicclic!"1 ?V.Brag<strong>in</strong>skyWe need a non-demolition detec<strong>to</strong>r at s<strong>in</strong>gle pho<strong>to</strong>n level…<strong>and</strong> a very good <strong>box</strong> <strong>to</strong> keep <strong>the</strong> <strong>pho<strong>to</strong>ns</strong> alive long enough
Cavity Quantum Electrodynamics:a stage <strong>to</strong> witness <strong>the</strong> <strong>in</strong>teraction between light <strong>and</strong> matter atOne a<strong>to</strong>m <strong>in</strong>teracts withone (or a few) pho<strong>to</strong>n(s)<strong>in</strong> a <strong>box</strong><strong>the</strong> most fundamental levelA sequence of a<strong>to</strong>ms crosses <strong>the</strong>cavity,couples with its field <strong>and</strong>carries away <strong>in</strong>formation about <strong>the</strong>trapped lightPho<strong>to</strong>ns bounc<strong>in</strong>g on mirrorspass many many times on <strong>the</strong>a<strong>to</strong>m: <strong>the</strong> cavity enhancestremendously <strong>the</strong>light-matter coupl<strong>in</strong>g6 cmThe bestmirrors <strong>in</strong> <strong>the</strong>world: morethan one billionbounces <strong>and</strong> afolded journeyof 40.000km(<strong>the</strong> earthcircumference)for <strong>the</strong> light!Pho<strong>to</strong>ns aretrapped formore than atenth of asecond!
RydbergAn extremely sensitive detec<strong>to</strong>r:<strong>the</strong> circular Rydberg a<strong>to</strong>mA<strong>to</strong>m <strong>in</strong> circular Rydberg state:electron on giant orbit(tenth of a micron diameter)Delocalized electron wavee (n=51)D.KleppnerA<strong>to</strong>m <strong>in</strong> ground state:electron on 10 -10 m diametreorbitElectron is localised on orbit by amicrowave pulse prepar<strong>in</strong>gsuperposition of two adjacentRydberg states: |e> ! |e> + |g>Schröd<strong>in</strong>ger kitteng (n=50)The localized wave packet revolves around nucleusat 51 GHz like a clock’s h<strong>and</strong> on a dial.Complex preparation with lasers <strong>and</strong> radiofrequency
When a<strong>to</strong>m <strong>in</strong>teracts with non-resonant light,<strong>the</strong> clock frequency is slightly modified by <strong>the</strong>light shift effect (Cohen-Tannoudji, 1961)Non-resonant a<strong>to</strong>m experienceslight-shifts proportional <strong>to</strong> <strong>the</strong>pho<strong>to</strong>n number N, with oppositesigns <strong>in</strong> levels e <strong>and</strong> gegThe shifts result <strong>in</strong> a phase shift of<strong>the</strong> a<strong>to</strong>mic dipole when a<strong>to</strong>mcrosses <strong>the</strong> cavity:!"(N) = N# 0# 0 : phase shift per pho<strong>to</strong>ncan be as large as $0 pho<strong>to</strong>n 1 pho<strong>to</strong>nMeasur<strong>in</strong>g !" amounts <strong>to</strong> a QND pho<strong>to</strong>n count<strong>in</strong>g
An artist’s view of set-up…Classical pulses(Ramsey <strong>in</strong>terferometer)N.Ramsey(D.W<strong>in</strong>el<strong>and</strong>’s PhDadvisor)CircularstatepreparationRydberga<strong>to</strong>msHigh Qcavitye or g?1 or 0?An a<strong>to</strong>mic clock delayed by <strong>pho<strong>to</strong>ns</strong> trapped <strong>in</strong>side
Birth, life <strong>and</strong> death of a pho<strong>to</strong>ne0,90 0,95 1,00 1,05 1,10 1,15 1,20g<strong>quantum</strong>jumpeg10Hundreds of a<strong>to</strong>mssee <strong>the</strong> samepho<strong>to</strong>n0,0 0,5 1,0 1,5 2,0 2,5S.Gleyzes et al, Nature, 446, 297 (2007)time (s)
Progressive collapse as n is p<strong>in</strong>ned down <strong>to</strong> one valuequi va gagner la course?Which number will w<strong>in</strong> <strong>the</strong> race?n = 7 6 5 4 3 2 1 0n = 7 6 5 4 3 2 1 0
Field <strong>quantum</strong> jumpsdue <strong>to</strong> cavity lossesPho<strong>to</strong>n number statesstabilized by <strong>quantum</strong>feedback(4 <strong>and</strong> 7 <strong>pho<strong>to</strong>ns</strong>)Pho<strong>to</strong>n numberPho<strong>to</strong>n numberPho<strong>to</strong>n numberPho<strong>to</strong>n numberC. Sayr<strong>in</strong> et al., Nature 477, 73 (2011)C.Guerl<strong>in</strong> et al, Nature, 448, 889 (2007)X. Zhou et al., Phys. Rev. . Lett. 108, 243602 (2012)
Explor<strong>in</strong>g <strong>the</strong> wave nature of trapped light<strong>and</strong> tam<strong>in</strong>g pho<strong>to</strong>nic Schröd<strong>in</strong>ger cats
Schröd<strong>in</strong>ger cat s<strong>to</strong>ry:A large system coupled <strong>to</strong> a s<strong>in</strong>glea<strong>to</strong>m ends up <strong>in</strong> a strangesuperposition…Our version:a coherentfield coupled<strong>to</strong> a s<strong>in</strong>glea<strong>to</strong>mcollapses <strong>in</strong><strong>to</strong>a superpositionof two fieldswith oppositephases
A coherent state of light frozen at a giventimeThe Wigner function is a 2D real function describ<strong>in</strong>g <strong>the</strong> stateof <strong>the</strong> field
R I PM.BruneJ-M.RaimondL.DavidovichN.ZagurySchröd<strong>in</strong>ger catstatedecoherenceClassical mixture of«!live!» <strong>and</strong> «!dead!»states
How s<strong>in</strong>gle a<strong>to</strong>m prepares Schröd<strong>in</strong>ger catstate of light1. S<strong>in</strong>gle a<strong>to</strong>m is prepared<strong>in</strong> R 1<strong>in</strong> a superposition ofe <strong>and</strong> gR 1 R 22. A<strong>to</strong>m shifts <strong>the</strong> fieldphase <strong>in</strong> two oppositedirections as it crosses C:superposition leads <strong>to</strong>entanglement <strong>in</strong> typicalSchröd<strong>in</strong>ger cat situation:field is a ‘meter’ read<strong>in</strong>ga<strong>to</strong>m’s energy3. A<strong>to</strong>mic states mixed aga<strong>in</strong> <strong>in</strong> R 2ma<strong>in</strong>ta<strong>in</strong>s cat’s ambiguity:Detect<strong>in</strong>g a<strong>to</strong>m <strong>in</strong> e or g projects field <strong>in</strong><strong>to</strong> cat statesuperposition!
Reconstructed Wigner function of a cat(modified version of QND measurement us<strong>in</strong>g sequence of a<strong>to</strong>ms cross<strong>in</strong>g C)Coherent componentsR I P2.5<strong>pho<strong>to</strong>ns</strong> onaverageQuantum<strong>in</strong>terference (cat’scoherence)S.Deléglise et al, Nature, 455, 510 (2008)
Fifty milliseconds <strong>in</strong> <strong>the</strong> life of aSchröd<strong>in</strong>ger cat(a movie of decoherence)W.Zurek
Earlier version of experiment:Brune et al, PRL,77, 4887 (1996)
Cavity QED: coupl<strong>in</strong>g real or artificial a<strong>to</strong>ms<strong>to</strong> a field trapped <strong>in</strong> a resona<strong>to</strong>rH.Kimble,G.RempeRydberg a<strong>to</strong>ms <strong>and</strong>microwaves <strong>in</strong>superconduct<strong>in</strong>g cavity(ENS)A<strong>to</strong>ms or <strong>quantum</strong> dotscoupled <strong>to</strong> opticalmicroresona<strong>to</strong>rsQuantum dots <strong>in</strong>semiconduc<strong>to</strong>rs.Pho<strong>to</strong>nic b<strong>and</strong>gapsCold a<strong>to</strong>ms <strong>in</strong> opticalcavities/microchipsYale,USBC,Saclay,ETH,Chalmers,NEC, NIST,Delft,MIT,Berkeley,Grenoble,etc…Circuit QED withJosephson junctionscoupled <strong>to</strong> coplanarl<strong>in</strong>es or 3D pho<strong>to</strong>n<strong>box</strong>es
A zoo of Schröd<strong>in</strong>ger catsA<strong>to</strong>mic CQEDDeléglise et al,Nature, 455, 510(2008)Circuit QED (Yale)Schröd<strong>in</strong>ger catgenerated by s<strong>in</strong>glea<strong>to</strong>m <strong>in</strong>dex effectG.Kirchmair, B.Vlastakis, M.Mirrahimi,Leghtas et al, <strong>in</strong> preparation (2012)Schröd<strong>in</strong>ger cat stategenerated by Kerr effectO<strong>the</strong>r circuit QED cats raised atUSBC (Santa Barbara)
Oc<strong>to</strong>ber 10 2012I.DotsenkoS.GleyzesJ-M.RaimondM.Brune
Same lab room,46 years earlier…F.LaloëOc<strong>to</strong>ber 1966 (after Kastler’s Nobel Prize announcement)C.Cohen-Tannoudji,Nobel 1997A.Kastler,Nobel 1966S.HJ.BrosselA.Omont
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