Chiral groundstate currents of interacting photons in a synthetic magnetic field

Transcription

1 Chirl groundstte currents of intercting photons in synthetic mgnetic field Pedrm Roushn Google Inc., Snt Brbr Chni, June 16 rxiv:

2 Google quntum rtificil intelligence tem Chrles Neill Anthony Megrnt Andrew Dunsworth Snt Brbr Hrdwre tem: Michel Fng (now Cltech) Prof. J. Mrtinis Los Angele theory tem: Collbortion: Dr. Hrtmut Neven Prof. Eliot Kpit

3 Clssicl vs. quntum computer Clssicl processor : Computtionl power ~ linerly with speed, RAM size, Stte of the rt: < 4 intercting spins untum processor : it is not going to work Computtionl power ~ exponentil with number of qubits 3 qubits Prllel processing of 3 =8 sttes? doubling the power: n ubits n+1 qubits

4 A quntum for quntum Nture isn't clssicl, dmmit, nd if you wnt to mke simultion of nture, you'd better mke it quntum mechnicl, nd by golly it's wonderful problem, becuse it doesn't look so esy. -- Richrd Feynmn (1981) Let nture clculte for us! Anlog simultor Digitl simultor Feynmn, Int. J. Theor. Phys. (198), Lloyd, Science (1996) Bulut & Nori, Science (9)

5 Myths bout quntum processor 1) untum pltforms tht need cryogenics re not futuristic ) Neutrino-ised qubits for gining longer coherence times 3) There is nothing interesting to do without error correction 4) We need exponentil speed-up

6 Controllbility Ultr-cold toms Engineering pltforms Spin qubits Trpped ions Mny body physics Bloch, Nture Physics (5) Long coherence, Room temp., Solid stte Toyli, et l., Nno Lett. 1 Monroe, et l., Science 13 High fidelity logic gtes Superconducting circuits while mintining coherence Full fledged quntum simultor Conventionl experiment + Sclbility

7 ) cos( ) / ( q ubit L C H n i ) (...) 6! 4!! (1 ) / ( 6 4 q ubit L C H h.o. H int H Brends et l., Nture (14), Kelly et l. Nture (15), Chen et l., PRL (14), Roushn et l., Nture (14) ) ( 1 k j k j hop q hop g H L M H M RWA... ) 1)( ( 6 1) ( ) 1/ ( 3.. n n n U n n U H n H int o h RWA RWA

8 The gmon rchitecture I 1 I M 1 (1 L (1 q M L q ) ) M 1 M M1M M L CP L C g g 1 / M1M L L A homebuilt vriometer cos( ) cos( ) q L C

9 Mny-body phses in intercting bosons A holistic tsk: 1) Strong interctions ) Synthetic guge fields 3) Engineering flt bnd structure

10 1) Fermionic systems Mny-body physics Fundmentl physics Topologicl computtion ) Bosonic systems?

11 Theory nd experiments so fr Cold toms nd trpped ions Superconducting qubits J. R. Abo-Sheer et l., Science (1) B. Predes et l., Solid Stte communiction (3) A. L. C. Hywrd et l., PRL (8) J. Cho et l., PRL (8) Y.-J. Lin et l., Nture (9) A. L. Fetter, RMP (9) M. Aidelsburger et l., PRL (13) V. Schweikhrd et l., PRL (14) H. Miyke et l., PRL (13) G. Jotzu et l., Nture (14) M. Hfezi et l., Nture Photonics (13) M. Rechtsmn et l., Nture (13) L. Lu et l., Nture Photonics (14) L. Tzung et l., Nture Photonics (14) J. Ningyun et l., PRX (15) S. Rghu et l., PRA (8) Z. Wng et l., Nture (9) A. Khnikev et l. Nture mterils (13) D. Hugel et l., PRA (14) S. Kessler nd F. Mrqurdt, Phys. Rev. A (14) M. Atl et l.,nture Physics (14) J. Flvin et l., PRX (14) A. Petrescu et l., PRA (1) J. Koch et l., PRA (1) A. Nunnenkmp et l., New J. of Physics (11) A. L. C. Hywrd et l., PRL (1) M. Hfezi et l., PRB (14) E. Kpit et l., PRX (14)

12 Fully controllble & coupled qubits

13 On nd off resonnce tunneling

14 H( t) Engineering complex hopping 3 i i i Z 3 i j g ij ( t)( i i i i ) modulting coupling terms where,, nd if Then, using RWA, the effective Hmiltonin becomes: is guge-invrint Universl two-qubit interctions: E. Kpit, PRA (15)

15 In the lb: Pulse sequence Then, using RWA, the effective Hmiltonin becomes: is guge-invrint

16 Single photon circultion

17 Single photon circultion TRS : ( t) ( t) if ( t) ( T t) TRS : ( t) ( T t)

18 Understnding decoherence nd dephsing T 1 15s, T s J. Koch et l., PRA (1)

19 N. A. Estep et l., Nture Physics (14) J. Kerckhoff et l., Phys. Rev. Applied (15) K. Fng et l., Nture Photonics (1) K. Fng et l., PRB (13) Clssicl non-reciprocity

20 Entnglement circultion OR

21 Evolution of the density mtrix

22 Signture of strong intercting photons 1 11

23 Signture of strong intercting photons 1 11

24 Signture of strong intercting photons 1 H int U U3 n( n 1) n( n 1)( n )... 6 U U MHz 3 H eff 11 3 jk g i i ( e jk jk j k e jk ) g 5MHz

25 ) ( g e g g g e g g T t H B B i i Adi eff ) ( 1 t H 1? TAdi Ground stte chirlity Adibtic rmping Y X X Y I t n I I out in ], [ 1 1 n H i t n ) ( i i e e i I define: mesure:

26 Chirl currents in groundstte

27 An opticl microgrph of the 9-qubit chip. At Google we re focusing on quntum computtion nd we re open to ides 1,$ vs. 1,,$ 11.5 mm

28 Come nd visit us t Snt Brbr! Google, Snt Brbr UCSB lb