51
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Hou Q, Yang W, Chen C, Yin Z. Generation of macroscopic Schrödinger cat state in diamond mechanical resonator. Sci Rep 2016; 6:37542. [PMID: 27876846 PMCID: PMC5120327 DOI: 10.1038/srep37542] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 10/27/2016] [Indexed: 12/03/2022] Open
Abstract
We propose a scheme to generate macroscopic Schrödinger cat state (SCS) in diamond mechanical resonator (DMR) via the dynamical strain-mediated coupling mechanism. In our model, the direct coupling between the nitrogen-vacancy (NV) center and lattice strain field enables coherent spin–phonon interactions in the quantum regime. Based on a cyclic Δ-type transition structure of the NV center constructed by combining the quantized mechanical strain field and a pair of external microwave fields, the populations of the different energy levels can be selectively transferred by controlling microwave fields, and the SCS can be created by adjusting the controllable parameters of the system. Furthermore, we demonstrate the nonclassicality of the mechanical SCS both in non-dissipative case and dissipative case. The experimental feasibility and challenge are justified using currently available technology.
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Affiliation(s)
- Qizhe Hou
- National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
| | - Wanli Yang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Changyong Chen
- Department of Physics, Shaoguan University, Shaoguan, Guangdong 512005, China
| | - Zhangqi Yin
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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52
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Hoff UB, Kollath-Bönig J, Neergaard-Nielsen JS, Andersen UL. Measurement-Induced Macroscopic Superposition States in Cavity Optomechanics. PHYSICAL REVIEW LETTERS 2016; 117:143601. [PMID: 27740796 DOI: 10.1103/physrevlett.117.143601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Indexed: 06/06/2023]
Abstract
A novel protocol for generating quantum superpositions of macroscopically distinct states of a bulk mechanical oscillator is proposed, compatible with existing optomechanical devices operating in the bad-cavity limit. By combining a pulsed optomechanical quantum nondemolition (QND) interaction with nonclassical optical resources and measurement-induced feedback, the need for strong single-photon coupling is avoided. We outline a three-pulse sequence of QND interactions encompassing squeezing-enhanced cooling by measurement, state preparation, and tomography.
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Affiliation(s)
- Ulrich B Hoff
- Department of Physics, Technical University of Denmark, Building 309, 2800 Kongens Lyngby, Denmark
- Australian Research Council Centre of Excellence for Engineered Quantum Systems (EQuS), School of Mathematics and Physics, The University of Queensland, St. Lucia QLD 4072, Australia
| | - Johann Kollath-Bönig
- Department of Physics, Technical University of Denmark, Building 309, 2800 Kongens Lyngby, Denmark
| | | | - Ulrik L Andersen
- Department of Physics, Technical University of Denmark, Building 309, 2800 Kongens Lyngby, Denmark
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53
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Yuan X, Liu K, Xu Y, Wang W, Ma Y, Zhang F, Yan Z, Vijay R, Sun L, Ma X. Experimental Quantum Randomness Processing Using Superconducting Qubits. PHYSICAL REVIEW LETTERS 2016; 117:010502. [PMID: 27419550 DOI: 10.1103/physrevlett.117.010502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Indexed: 06/06/2023]
Abstract
Coherently manipulating multipartite quantum correlations leads to remarkable advantages in quantum information processing. A fundamental question is whether such quantum advantages persist only by exploiting multipartite correlations, such as entanglement. Recently, Dale, Jennings, and Rudolph negated the question by showing that a randomness processing, quantum Bernoulli factory, using quantum coherence, is strictly more powerful than the one with classical mechanics. In this Letter, focusing on the same scenario, we propose a theoretical protocol that is classically impossible but can be implemented solely using quantum coherence without entanglement. We demonstrate the protocol by exploiting the high-fidelity quantum state preparation and measurement with a superconducting qubit in the circuit quantum electrodynamics architecture and a nearly quantum-limited parametric amplifier. Our experiment shows the advantage of using quantum coherence of a single qubit for information processing even when multipartite correlation is not present.
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Affiliation(s)
- Xiao Yuan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Ke Liu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Yuan Xu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Weiting Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Yuwei Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Fang Zhang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Zhaopeng Yan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - R Vijay
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Luyan Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Xiongfeng Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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54
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Joo J, Ginossar E. Efficient scheme for hybrid teleportation via entangled coherent states in circuit quantum electrodynamics. Sci Rep 2016; 6:26338. [PMID: 27245775 PMCID: PMC4887884 DOI: 10.1038/srep26338] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 04/20/2016] [Indexed: 11/29/2022] Open
Abstract
We propose a deterministic scheme for teleporting an unknown qubit state through continuous-variable entangled states in superconducting circuits. The qubit is a superconducting two-level system and the bipartite quantum channel is a microwave photonic entangled coherent state between two cavities. A Bell-type measurement performed on the hybrid state of solid and photonic states transfers a discrete-variable unknown electronic state to a continuous-variable photonic cat state in a cavity mode. In order to facilitate the implementation of such complex protocols we propose a design for reducing the self-Kerr nonlinearity in the cavity. The teleporation scheme enables quantum information processing operations with circuit-QED based on entangled coherent states. These include state verification and single-qubit operations with entangled coherent states. These are shown to be experimentally feasible with the state of the art superconducting circuits.
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Affiliation(s)
- Jaewoo Joo
- Advanced Technology Institute and Department of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul 02455, South Korea
| | - Eran Ginossar
- Advanced Technology Institute and Department of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom
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55
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Wang C, Gao YY, Reinhold P, Heeres RW, Ofek N, Chou K, Axline C, Reagor M, Blumoff J, Sliwa KM, Frunzio L, Girvin SM, Jiang L, Mirrahimi M, Devoret MH, Schoelkopf RJ. A Schrödinger cat living in two boxes. Science 2016; 352:1087-91. [DOI: 10.1126/science.aaf2941] [Citation(s) in RCA: 189] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 04/14/2016] [Indexed: 11/02/2022]
Affiliation(s)
- Chen Wang
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - Yvonne Y. Gao
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - Philip Reinhold
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - R. W. Heeres
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - Nissim Ofek
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - Kevin Chou
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - Christopher Axline
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - Matthew Reagor
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - Jacob Blumoff
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - K. M. Sliwa
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - L. Frunzio
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - S. M. Girvin
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - Liang Jiang
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - M. Mirrahimi
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
- INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
| | - M. H. Devoret
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
| | - R. J. Schoelkopf
- Department of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA
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56
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Slodička L, Marek P, Filip R. Deterministic nonclassicality from thermal states. OPTICS EXPRESS 2016; 24:7858-7870. [PMID: 27137228 DOI: 10.1364/oe.24.007858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Coupling an oscillator to a single two-level system is one of the most fundamental interactions in quantum physics. We report on a dynamical effect during which a thermal state of an oscillator is unconditionally transformed to a highly nonclassical state with negative Wigner function values by mere absorbtion by a single uncontrolled two-level system. This complements the traditional test of Rabi oscillations and it serves as a simply measurable witness that the process in question is highly nonclassical. The process is experimentally feasible with possible experimental implementation in a number of experimental platforms with intrinsic Jaynes-Cummings interaction and it has the potential of enabling deterministic generation of nonclassical quantum states.
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57
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Albert VV, Shu C, Krastanov S, Shen C, Liu RB, Yang ZB, Schoelkopf RJ, Mirrahimi M, Devoret MH, Jiang L. Holonomic Quantum Control with Continuous Variable Systems. PHYSICAL REVIEW LETTERS 2016; 116:140502. [PMID: 27104689 DOI: 10.1103/physrevlett.116.140502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Indexed: 06/05/2023]
Abstract
Universal computation of a quantum system consisting of superpositions of well-separated coherent states of multiple harmonic oscillators can be achieved by three families of adiabatic holonomic gates. The first gate consists of moving a coherent state around a closed path in phase space, resulting in a relative Berry phase between that state and the other states. The second gate consists of "colliding" two coherent states of the same oscillator, resulting in coherent population transfer between them. The third gate is an effective controlled-phase gate on coherent states of two different oscillators. Such gates should be realizable via reservoir engineering of systems that support tunable nonlinearities, such as trapped ions and circuit QED.
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Affiliation(s)
- Victor V Albert
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut, USA
| | - Chi Shu
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut, USA
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Stefan Krastanov
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut, USA
| | - Chao Shen
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut, USA
| | - Ren-Bao Liu
- Department of Physics and Centre for Quantum Coherence, The Chinese University of Hong Kong, Hong Kong, China
| | - Zhen-Biao Yang
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut, USA
- Department of Physics, Fuzhou University, Fuzhou, China
| | - Robert J Schoelkopf
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut, USA
| | - Mazyar Mirrahimi
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut, USA
- INRIA Paris-Rocquencourt, Domaine de Voluceau, Le Chesnay Cedex, France
| | - Michel H Devoret
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut, USA
| | - Liang Jiang
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut, USA
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58
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Dong L, Wang JX, Li QY, Shen HZ, Dong HK, Xiu XM, Gao YJ. Single logical qubit information encoding scheme with the minimal optical decoherence-free subsystem. OPTICS LETTERS 2016; 41:1030-1033. [PMID: 26974108 DOI: 10.1364/ol.41.001030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a scheme for encoding single logical qubit information, which is immune to collective decoherence acting on Hilbert space spanned by the corresponding states. The scheme needs a spatial entanglement gate and a polarization entanglement gate, which are realized with the assistance of weak cross-Kerr nonlinear interaction between photons and coherent states via Kerr media. Under the condition of sufficient large phase shifts, single logical qubit information can be encoded into this minimal optical decoherence-free subsystem with near-unity fidelity. Together with the mature techniques of measurement and classical feed forward, simple linear optical elements are applied to complete the encoding task, which offers the feasibility of this scheme for protecting quantum information against decoherence.
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59
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Garcés R, de Valcárcel GJ. Strong vacuum squeezing from bichromatically driven Kerrlike cavities: from optomechanics to superconducting circuits. Sci Rep 2016; 6:21964. [PMID: 26916946 PMCID: PMC4768168 DOI: 10.1038/srep21964] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/03/2016] [Indexed: 11/29/2022] Open
Abstract
Squeezed light, displaying less fluctuation than vacuum in some observable, is key in the flourishing field of quantum technologies. Optical or microwave cavities containing a Kerr nonlinearity are known to potentially yield large levels of squeezing, which have been recently observed in optomechanics and nonlinear superconducting circuit platforms. Such Kerr-cavity squeezing however suffers from two fundamental drawbacks. First, optimal squeezing requires working close to turning points of a bistable cycle, which are highly unstable against noise thus rendering optimal squeezing inaccessible. Second, the light field has a macroscopic coherent component corresponding to the pump, making it less versatile than the so-called squeezed vacuum, characterised by a null mean field. Here we prove analytically and numerically that the bichromatic pumping of optomechanical and superconducting circuit cavities removes both limitations. This finding should boost the development of a new generation of robust vacuum squeezers in the microwave and optical domains with current technology.
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Affiliation(s)
- Rafael Garcés
- Departament d'Òptica, Facultat de Física, Universitat de València, Dr. Moliner 50, 46100 Burjassot (Valencia), Spain
| | - Germán J de Valcárcel
- Departament d'Òptica, Facultat de Física, Universitat de València, Dr. Moliner 50, 46100 Burjassot (Valencia), Spain
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60
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Bifurcation-based adiabatic quantum computation with a nonlinear oscillator network. Sci Rep 2016; 6:21686. [PMID: 26899997 PMCID: PMC4761947 DOI: 10.1038/srep21686] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 01/27/2016] [Indexed: 11/08/2022] Open
Abstract
The dynamics of nonlinear systems qualitatively change depending on their parameters, which is called bifurcation. A quantum-mechanical nonlinear oscillator can yield a quantum superposition of two oscillation states, known as a Schrödinger cat state, via quantum adiabatic evolution through its bifurcation point. Here we propose a quantum computer comprising such quantum nonlinear oscillators, instead of quantum bits, to solve hard combinatorial optimization problems. The nonlinear oscillator network finds optimal solutions via quantum adiabatic evolution, where nonlinear terms are increased slowly, in contrast to conventional adiabatic quantum computation or quantum annealing, where quantum fluctuation terms are decreased slowly. As a result of numerical simulations, it is concluded that quantum superposition and quantum fluctuation work effectively to find optimal solutions. It is also notable that the present computer is analogous to neural computers, which are also networks of nonlinear components. Thus, the present scheme will open new possibilities for quantum computation, nonlinear science, and artificial intelligence.
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61
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Xu P, Yang XC, Mei F, Xue ZY. Controllable high-fidelity quantum state transfer and entanglement generation in circuit QED. Sci Rep 2016; 6:18695. [PMID: 26804326 PMCID: PMC4726278 DOI: 10.1038/srep18695] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 11/23/2015] [Indexed: 11/09/2022] Open
Abstract
We propose a scheme to realize controllable quantum state transfer and entanglement generation among transmon qubits in the typical circuit QED setup based on adiabatic passage. Through designing the time-dependent driven pulses applied on the transmon qubits, we find that fast quantum sate transfer can be achieved between arbitrary two qubits and quantum entanglement among the qubits also can also be engineered. Furthermore, we numerically analyzed the influence of the decoherence on our scheme with the current experimental accessible systematical parameters. The result shows that our scheme is very robust against both the cavity decay and qubit relaxation, the fidelities of the state transfer and entanglement preparation process could be very high. In addition, our scheme is also shown to be insensitive to the inhomogeneous of qubit-resonator coupling strengths.
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Affiliation(s)
- Peng Xu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 230039, China
| | - Xu-Chen Yang
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, and School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
| | - Feng Mei
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 230039, China
| | - Zheng-Yuan Xue
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, and School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
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62
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Hofer PP, Clerk AA. Negative Full Counting Statistics Arise from Interference Effects. PHYSICAL REVIEW LETTERS 2016; 116:013603. [PMID: 26799019 DOI: 10.1103/physrevlett.116.013603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Indexed: 06/05/2023]
Abstract
The Keldysh-ordered full counting statistics is a quasiprobability distribution describing the fluctuations of a time-integrated quantum observable. While it is well known that this distribution can fail to be positive, the interpretation and origin of this negativity has been somewhat unclear. Here, we show how the full counting statistics can be tied to trajectories through Hilbert space, and how this directly connects negative quasiprobabilities to an unusual interference effect. Our findings are illustrated with the example of energy fluctuations in a driven bosonic resonator; we discuss how negative quasiprobability here could be detected experimentally using superconducting microwave circuits.
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Affiliation(s)
- Patrick P Hofer
- Department of Physics, McGill University, Montreal, Quebec, Canada H3A 2T8
- Département de Physique Théorique, Université de Genève, 1211 Genève, Switzerland
| | - A A Clerk
- Department of Physics, McGill University, Montreal, Quebec, Canada H3A 2T8
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63
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Zheng SB, Zhong YP, Xu K, Wang QJ, Wang H, Shen LT, Yang CP, Martinis JM, Cleland AN, Han SY. Quantum Delayed-Choice Experiment with a Beam Splitter in a Quantum Superposition. PHYSICAL REVIEW LETTERS 2015; 115:260403. [PMID: 26764976 DOI: 10.1103/physrevlett.115.260403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Indexed: 06/05/2023]
Abstract
A quantum system can behave as a wave or as a particle, depending on the experimental arrangement. When, for example, measuring a photon using a Mach-Zehnder interferometer, the photon acts as a wave if the second beam splitter is inserted, but as a particle if this beam splitter is omitted. The decision of whether or not to insert this beam splitter can be made after the photon has entered the interferometer, as in Wheeler's famous delayed-choice thought experiment. In recent quantum versions of this experiment, this decision is controlled by a quantum ancilla, while the beam splitter is itself still a classical object. Here, we propose and realize a variant of the quantum delayed-choice experiment. We configure a superconducting quantum circuit as a Ramsey interferometer, where the element that acts as the first beam splitter can be put in a quantum superposition of its active and inactive states, as verified by the negative values of its Wigner function. We show that this enables the wave and particle aspects of the system to be observed with a single setup, without involving an ancilla that is not itself a part of the interferometer. We also study the transition of this quantum beam splitter from a quantum to a classical object due to decoherence, as observed by monitoring the interferometer output.
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Affiliation(s)
- Shi-Biao Zheng
- Department of Physics, Fuzhou University, Fuzhou 350116, China
| | - You-Peng Zhong
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Kai Xu
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Qi-Jue Wang
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - H Wang
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Li-Tuo Shen
- Department of Physics, Fuzhou University, Fuzhou 350116, China
| | - Chui-Ping Yang
- Department of Physics, Hangzhou Normal University, Hangzhou 310036, China
| | - John M Martinis
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - A N Cleland
- Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Si-Yuan Han
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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64
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Fischer UR, Kang MK. "Photonic" Cat States from Strongly Interacting Matter Waves. PHYSICAL REVIEW LETTERS 2015; 115:260404. [PMID: 26764977 DOI: 10.1103/physrevlett.115.260404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Indexed: 06/05/2023]
Abstract
We consider ultracold quantum gases of scalar bosons residing in a coupling strength-density regime in which they constitute a twofold fragmented condensate trapped in a single well. It is shown that the corresponding quantum states are, in the appropriate Fock space basis, identical to the photon cat states familiar in quantum optics, which correspond to superpositions of coherent states of the light field with a phase difference of π. In marked distinction to photon cat states, however, the very existence of matter-wave cat states crucially depends on the many-body correlations of the constituent bosons. We consequently establish that the quadratures of the effective "photons," expressing the highly nonclassical nature of the macroscopic matter-wave superposition state, can be experimentally accessed by measuring the density-density correlations of the interacting quantum gas.
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Affiliation(s)
- Uwe R Fischer
- Department of Physics and Astronomy, Center for Theoretical Physics, Seoul National University, 151-747 Seoul, Korea
| | - Myung-Kyun Kang
- Department of Physics and Astronomy, Center for Theoretical Physics, Seoul National University, 151-747 Seoul, Korea
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65
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Friis N, Melnikov AA, Kirchmair G, Briegel HJ. Coherent controlization using superconducting qubits. Sci Rep 2015; 5:18036. [PMID: 26667893 PMCID: PMC4678369 DOI: 10.1038/srep18036] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/10/2015] [Indexed: 11/08/2022] Open
Abstract
Coherent controlization, i.e., coherent conditioning of arbitrary single- or multi-qubit operations on the state of one or more control qubits, is an important ingredient for the flexible implementation of many algorithms in quantum computation. This is of particular significance when certain subroutines are changing over time or when they are frequently modified, such as in decision-making algorithms for learning agents. We propose a scheme to realize coherent controlization for any number of superconducting qubits coupled to a microwave resonator. For two and three qubits, we present an explicit construction that is of high relevance for quantum learning agents. We demonstrate the feasibility of our proposal, taking into account loss, dephasing, and the cavity self-Kerr effect.
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Affiliation(s)
- Nicolai Friis
- Institute for Theoretical Physics, University of Innsbruck, Technikerstraße 21a, A-6020 Innsbruck, Austria
| | - Alexey A. Melnikov
- Institute for Theoretical Physics, University of Innsbruck, Technikerstraße 21a, A-6020 Innsbruck, Austria
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Technikerstraße 21a, A-6020 Innsbruck, Austria
| | - Gerhard Kirchmair
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Technikerstraße 21a, A-6020 Innsbruck, Austria
- Institute for Experimental Physics, University of Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
| | - Hans J. Briegel
- Institute for Theoretical Physics, University of Innsbruck, Technikerstraße 21a, A-6020 Innsbruck, Austria
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66
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Castaños O, Calixto M, Pérez-Bernal F, Romera E. Identifying the order of a quantum phase transition by means of Wehrl entropy in phase space. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:052106. [PMID: 26651646 DOI: 10.1103/physreve.92.052106] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Indexed: 06/05/2023]
Abstract
We propose a method to identify the order of a quantum phase transition by using area measures of the ground state in phase space. We illustrate our proposal by analyzing the well known example of the quantum cusp and four different paradigmatic boson models: Dicke, Lipkin-Meshkov-Glick, interacting boson model, and vibron model.
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Affiliation(s)
- Octavio Castaños
- Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apartado Postal 70-543, 04510 Distrito Federal, Mexico
| | - Manuel Calixto
- Departamento de Matemática Aplicada, Facultad de Ciencias, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain
| | - Francisco Pérez-Bernal
- Departamento de Física Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, Campus del Carmen, Avenida de las Fuerzas Armadas s/n, 21071 Huelva, Spain
| | - Elvira Romera
- Departamento de Física Atómica, Molecular y Nuclear and Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Fuentenueva s/n, 18071 Granada, Spain
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67
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Holland ET, Vlastakis B, Heeres RW, Reagor MJ, Vool U, Leghtas Z, Frunzio L, Kirchmair G, Devoret MH, Mirrahimi M, Schoelkopf RJ. Single-Photon-Resolved Cross-Kerr Interaction for Autonomous Stabilization of Photon-Number States. PHYSICAL REVIEW LETTERS 2015; 115:180501. [PMID: 26565448 DOI: 10.1103/physrevlett.115.180501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Indexed: 06/05/2023]
Abstract
Quantum states can be stabilized in the presence of intrinsic and environmental losses by either applying an active feedback condition on an ancillary system or through reservoir engineering. Reservoir engineering maintains a desired quantum state through a combination of drives and designed entropy evacuation. We propose and implement a quantum-reservoir engineering protocol that stabilizes Fock states in a microwave cavity. This protocol is realized with a circuit quantum electrodynamics platform where a Josephson junction provides direct, nonlinear coupling between two superconducting waveguide cavities. The nonlinear coupling results in a single-photon-resolved cross-Kerr effect between the two cavities enabling a photon-number-dependent coupling to a lossy environment. The quantum state of the microwave cavity is discussed in terms of a net polarization and is analyzed by a measurement of its steady state Wigner function.
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Affiliation(s)
- E T Holland
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - B Vlastakis
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - R W Heeres
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - M J Reagor
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - U Vool
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Z Leghtas
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - L Frunzio
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - G Kirchmair
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Experimental Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - M H Devoret
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - M Mirrahimi
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
- INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
| | - R J Schoelkopf
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
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68
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Yuan M, Singh V, Blanter YM, Steele GA. Large cooperativity and microkelvin cooling with a three-dimensional optomechanical cavity. Nat Commun 2015; 6:8491. [PMID: 26450772 PMCID: PMC4633713 DOI: 10.1038/ncomms9491] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 08/27/2015] [Indexed: 11/09/2022] Open
Abstract
In cavity optomechanics, light is used to control mechanical motion. A central goal of the field is achieving single-photon strong coupling, which would enable the creation of quantum superposition states of motion. Reaching this limit requires significant improvements in optomechanical coupling and cavity coherence. Here we introduce an optomechanical architecture consisting of a silicon nitride membrane coupled to a three-dimensional superconducting microwave cavity. Exploiting their large quality factors, we achieve an optomechanical cooperativity of 146,000 and perform sideband cooling of the kilohertz-frequency membrane motion to 34±5 μK, the lowest mechanical mode temperature reported to date. The achieved cooling is limited only by classical noise of the signal generator, and should extend deep into the ground state with superconducting filters. Our results suggest that this realization of optomechanics has the potential to reach the regimes of ultra-large cooperativity and single-photon strong coupling, opening up a new generation of experiments.
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Affiliation(s)
- Mingyun Yuan
- Kavli Institute of Nanoscience, Department of Quantum Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
| | - Vibhor Singh
- Kavli Institute of Nanoscience, Department of Quantum Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
| | - Yaroslav M Blanter
- Kavli Institute of Nanoscience, Department of Quantum Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
| | - Gary A Steele
- Kavli Institute of Nanoscience, Department of Quantum Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
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69
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Heeres RW, Vlastakis B, Holland E, Krastanov S, Albert VV, Frunzio L, Jiang L, Schoelkopf RJ. Cavity State Manipulation Using Photon-Number Selective Phase Gates. PHYSICAL REVIEW LETTERS 2015; 115:137002. [PMID: 26451578 DOI: 10.1103/physrevlett.115.137002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Indexed: 06/05/2023]
Abstract
The large available Hilbert space and high coherence of cavity resonators make these systems an interesting resource for storing encoded quantum bits. To perform a quantum gate on this encoded information, however, complex nonlinear operations must be applied to the many levels of the oscillator simultaneously. In this work, we introduce the selective number-dependent arbitrary phase (snap) gate, which imparts a different phase to each Fock-state component using an off-resonantly coupled qubit. We show that the snap gate allows control over the quantum phases by correcting the unwanted phase evolution due to the Kerr effect. Furthermore, by combining the snap gate with oscillator displacements, we create a one-photon Fock state with high fidelity. Using just these two controls, one can construct arbitrary unitary operations, offering a scalable route to performing logical manipulations on oscillator-encoded qubits.
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Affiliation(s)
- Reinier W Heeres
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Brian Vlastakis
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Eric Holland
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Stefan Krastanov
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Victor V Albert
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Luigi Frunzio
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Liang Jiang
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Robert J Schoelkopf
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
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70
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Bretheau L, Campagne-Ibarcq P, Flurin E, Mallet F, Huard B. Quantum dynamics of an electromagnetic mode that cannot contain N photons. Science 2015; 348:776-9. [DOI: 10.1126/science.1259345] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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71
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Li HC, Ge GQ, Zhang HY. Dressed-state realization of the transition from electromagnetically induced transparency to Autler-Townes splitting in superconducting circuits. OPTICS EXPRESS 2015; 23:9844-9851. [PMID: 25969025 DOI: 10.1364/oe.23.009844] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigate electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS) in a driven three-level superconducting artificial system which is a dressed-state system resulting from the coupling of a superconducting charge qubit (an artificial atom) and a transmission line resonator. In the frame of the dressed-state approach and steady-state approximation, we study the linear absorption of the dressed artificial system to a weak probe signal in depth. In light of the spectrum-decomposition method and some other restrictions, we obtain the explicit conditions for the dressed-state realization of EIT and ATS and present a corresponding "phase diagram". In contrast to usual bare systems, these conditions given in the dressed system have an extra dependency on the qubit-resonator parameters. And by varying the qubit's Josephson coupling energy we demonstrate a transition from EIT to ATS.
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72
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Leghtas Z, Touzard S, Pop IM, Kou A, Vlastakis B, Petrenko A, Sliwa KM, Narla A, Shankar S, Hatridge MJ, Reagor M, Frunzio L, Schoelkopf RJ, Mirrahimi M, Devoret MH. Confining the state of light to a quantum manifold by engineered two-photon loss. Science 2015; 347:853-7. [DOI: 10.1126/science.aaa2085] [Citation(s) in RCA: 262] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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73
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Kong WC, Deng GW, Li SX, Li HO, Cao G, Xiao M, Guo GP. Introduction of DC line structures into a superconducting microwave 3D cavity. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:023108. [PMID: 25725824 DOI: 10.1063/1.4913252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report a technique that can noninvasively add multiple DC wires into a 3D superconducting microwave cavity for electronic devices that require DC electrical terminals. We studied the influence of our DC lines on the cavity performance systematically. We found that the quality factor of the cavity is reduced if any of the components of the electrical wires cross the cavity equipotential planes. Using this technique, we were able to incorporate a quantum dot (QD) device into a 3D cavity. We then controlled and measured the QD transport signal using the DC lines. We have also studied the heating effects of the QD by the microwave photons in the cavity.
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Affiliation(s)
- Wei-Cheng Kong
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Guang-Wei Deng
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shu-Xiao Li
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Hai-Ou Li
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Gang Cao
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ming Xiao
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Guo-Ping Guo
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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74
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Marcos D, Widmer P, Rico E, Hafezi M, Rabl P, Wiese UJ, Zoller P. Two-dimensional lattice gauge theories with superconducting quantum circuits. ANNALS OF PHYSICS 2014; 351:634-654. [PMID: 25512676 PMCID: PMC4263216 DOI: 10.1016/j.aop.2014.09.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 09/10/2014] [Indexed: 05/27/2023]
Abstract
A quantum simulator of [Formula: see text] lattice gauge theories can be implemented with superconducting circuits. This allows the investigation of confined and deconfined phases in quantum link models, and of valence bond solid and spin liquid phases in quantum dimer models. Fractionalized confining strings and the real-time dynamics of quantum phase transitions are accessible as well. Here we show how state-of-the-art superconducting technology allows us to simulate these phenomena in relatively small circuit lattices. By exploiting the strong non-linear couplings between quantized excitations emerging when superconducting qubits are coupled, we show how to engineer gauge invariant Hamiltonians, including ring-exchange and four-body Ising interactions. We demonstrate that, despite decoherence and disorder effects, minimal circuit instances allow us to investigate properties such as the dynamics of electric flux strings, signaling confinement in gauge invariant field theories. The experimental realization of these models in larger superconducting circuits could address open questions beyond current computational capability.
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Affiliation(s)
- D. Marcos
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
| | - P. Widmer
- Albert Einstein Center, Institute for Theoretical Physics, Bern University, CH-3012, Bern, Switzerland
| | - E. Rico
- IPCMS (UMR 7504) and ISIS (UMR 7006), University of Strasbourg and CNRS, 67000 Strasbourg, France
| | - M. Hafezi
- Joint Quantum Institute, NIST/University of Maryland, College Park 20742, USA
- Department of Electrical Engineering and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742, USA
| | - P. Rabl
- Institute of Atomic and Subatomic Physics, TU Wien, Stadionallee 2, 1020 Wien, Austria
| | - U.-J. Wiese
- Albert Einstein Center, Institute for Theoretical Physics, Bern University, CH-3012, Bern, Switzerland
| | - P. Zoller
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
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75
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Zhang X, Zou CL, Jiang L, Tang HX. Strongly coupled magnons and cavity microwave photons. PHYSICAL REVIEW LETTERS 2014; 113:156401. [PMID: 25375725 DOI: 10.1103/physrevlett.113.156401] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Indexed: 05/23/2023]
Abstract
We realize a cavity magnon-microwave photon system in which a magnetic dipole interaction mediates strong coupling between the collective motion of a large number of spins in a ferrimagnet and the microwave field in a three-dimensional cavity. By scaling down the cavity size and increasing the number of spins, an ultrastrong coupling regime is achieved with a cooperativity reaching 12,600. Interesting dynamic features including classical Rabi-like oscillation, magnetically induced transparency, and the Purcell effect are demonstrated in this highly versatile platform, highlighting its great potential for coherent information processing.
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Affiliation(s)
- Xufeng Zhang
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, USA
| | - Chang-Ling Zou
- Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA and Key Lab of Quantum Information, University of Science and Technology of China, Hefei 230026, Anhui, People's Republic of China
| | - Liang Jiang
- Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Hong X Tang
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, USA
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76
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Sun L, Petrenko A, Leghtas Z, Vlastakis B, Kirchmair G, Sliwa KM, Narla A, Hatridge M, Shankar S, Blumoff J, Frunzio L, Mirrahimi M, Devoret MH, Schoelkopf RJ. Tracking photon jumps with repeated quantum non-demolition parity measurements. Nature 2014; 511:444-8. [DOI: 10.1038/nature13436] [Citation(s) in RCA: 169] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 05/06/2014] [Indexed: 12/26/2022]
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77
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Jeffrey E, Sank D, Mutus JY, White TC, Kelly J, Barends R, Chen Y, Chen Z, Chiaro B, Dunsworth A, Megrant A, O'Malley PJJ, Neill C, Roushan P, Vainsencher A, Wenner J, Cleland AN, Martinis JM. Fast accurate state measurement with superconducting qubits. PHYSICAL REVIEW LETTERS 2014; 112:190504. [PMID: 24877923 DOI: 10.1103/physrevlett.112.210501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Indexed: 05/23/2023]
Abstract
Faster and more accurate state measurement is required for progress in superconducting qubit experiments with greater numbers of qubits and advanced techniques such as feedback. We have designed a multiplexed measurement system with a bandpass filter that allows fast measurement without increasing environmental damping of the qubits. We use this to demonstrate simultaneous measurement of four qubits on a single superconducting integrated circuit, the fastest of which can be measured to 99.8% accuracy in 140 ns. This accuracy and speed is suitable for advanced multiqubit experiments including surface-code error correction.
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Affiliation(s)
- Evan Jeffrey
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - Daniel Sank
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - J Y Mutus
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - T C White
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - J Kelly
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - R Barends
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - Y Chen
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - Z Chen
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - B Chiaro
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - A Dunsworth
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - A Megrant
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - P J J O'Malley
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - C Neill
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - P Roushan
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - A Vainsencher
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - J Wenner
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - A N Cleland
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
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78
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Horowitz JM, Jacobs K. Quantum effects improve the energy efficiency of feedback control. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:042134. [PMID: 24827219 DOI: 10.1103/physreve.89.042134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Indexed: 06/03/2023]
Abstract
The laws of thermodynamics apply equally well to quantum systems as to classical systems, and because of this, quantum effects do not change the fundamental thermodynamic efficiency of isothermal refrigerators or engines. We show that, despite this fact, quantum mechanics permits measurement-based feedback control protocols that are more thermodynamically efficient than their classical counterparts. As part of our analysis, we perform a detailed accounting of the thermodynamics of unitary feedback control and elucidate the sources of inefficiency in measurement-based and coherent feedback.
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Affiliation(s)
- Jordan M Horowitz
- Department of Physics, University of Massachusetts at Boston, Boston, Massachusetts 02125, USA
| | - Kurt Jacobs
- Department of Physics, University of Massachusetts at Boston, Boston, Massachusetts 02125, USA and Hearne Institute for Theoretical Physics, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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79
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Sames C, Chibani H, Hamsen C, Altin PA, Wilk T, Rempe G. Antiresonance phase shift in strongly coupled cavity QED. PHYSICAL REVIEW LETTERS 2014; 112:043601. [PMID: 24580448 DOI: 10.1103/physrevlett.112.043601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Indexed: 06/03/2023]
Abstract
We investigate phase shifts in the strong coupling regime of single-atom cavity quantum electrodynamics. On the light transmitted through the system, we observe a phase shift associated with an antiresonance and show that both its frequency and width depend solely on the atom, despite the strong coupling to the cavity. This shift is optically controllable and reaches 140°--the largest ever reported for a single emitter. Our result offers a new technique for the characterization of complex integrated quantum circuits.
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Affiliation(s)
- C Sames
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany
| | - H Chibani
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany
| | - C Hamsen
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany
| | - P A Altin
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany
| | - T Wilk
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany
| | - G Rempe
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany
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80
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Vlastakis B, Kirchmair G, Leghtas Z, Nigg SE, Frunzio L, Girvin SM, Mirrahimi M, Devoret MH, Schoelkopf RJ. Deterministically encoding quantum information using 100-photon Schrödinger cat states. Science 2013; 342:607-10. [PMID: 24072821 DOI: 10.1126/science.1243289] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In contrast to a single quantum bit, an oscillator can store multiple excitations and coherences provided one has the ability to generate and manipulate complex multiphoton states. We demonstrate multiphoton control by using a superconducting transmon qubit coupled to a waveguide cavity resonator with a highly ideal off-resonant coupling. This dispersive interaction is much greater than decoherence rates and higher-order nonlinearities to allow simultaneous manipulation of hundreds of photons. With a tool set of conditional qubit-photon logic, we mapped an arbitrary qubit state to a superposition of coherent states, known as a "cat state." We created cat states as large as 111 photons and extended this protocol to create superpositions of up to four coherent states. This control creates a powerful interface between discrete and continuous variable quantum computation and could enable applications in metrology and quantum information processing.
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Affiliation(s)
- Brian Vlastakis
- Department of Physics and Department of Applied Physics, Yale University, New Haven, CT 06511, USA
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81
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Firstenberg O, Peyronel T, Liang QY, Gorshkov AV, Lukin MD, Vuletić V. Attractive photons in a quantum nonlinear medium. Nature 2013; 502:71-5. [DOI: 10.1038/nature12512] [Citation(s) in RCA: 300] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 07/29/2013] [Indexed: 11/09/2022]
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82
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Haroche S. Über die Kontrolle von Photonen im Kasten und die Erforschung des Übergangs von der Quanten- zur klassischen Welt (Nobel-Aufsatz). Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201302971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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83
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Marcos D, Rabl P, Rico E, Zoller P. Superconducting circuits for quantum simulation of dynamical gauge fields. PHYSICAL REVIEW LETTERS 2013; 111:110504. [PMID: 24074064 DOI: 10.1103/physrevlett.111.110504] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Indexed: 06/02/2023]
Abstract
We describe a superconducting-circuit lattice design for the implementation and simulation of dynamical lattice gauge theories. We illustrate our proposal by analyzing a one-dimensional U(1) quantum-link model, where superconducting qubits play the role of matter fields on the lattice sites and the gauge fields are represented by two coupled microwave resonators on each link between neighboring sites. A detailed analysis of a minimal experimental protocol for probing the physics related to string breaking effects shows that, despite the presence of decoherence in these systems, distinctive phenomena from condensed-matter and high-energy physics can be visualized with state-of-the-art technology in small superconducting-circuit arrays.
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Affiliation(s)
- D Marcos
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
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84
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Haroche S. Controlling photons in a box and exploring the quantum to classical boundary (Nobel Lecture). Angew Chem Int Ed Engl 2013; 52:10159-78. [PMID: 24038846 DOI: 10.1002/anie.201302971] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Indexed: 11/06/2022]
Abstract
Microwave photons trapped in a superconducting cavity constitute an ideal system to realize some of the thought experiments imagined by the founding fathers of quantum physics. The interaction of these trapped photons with Rydberg atoms crossing the cavity illustrates fundamental aspects of measurement theory. The experiments performed with this "photon box" at Ecole Normale Supérieure (ENS) belong to the domain of quantum optics called "Cavity Quantum Electrodynamics". We have realized the non-destructive counting of photons, the recording of field quantum jumps, the preparation and reconstruction of "Schrödinger cat" states of radiation and the study of their decoherence, which provides a striking illustration of the transition from the quantum to the classical world. These experiments have also led to the demonstration of basic steps in quantum information processing, including the deterministic entanglement of atoms and the realization of quantum gates using atoms and photons as quantum bits. This lecture starts by an introduction stressing the connection between the ENS photon box and the ion trap experiments of David Wineland, whose accompanying lecture recalls his own contribution to the field of single particle control. I give then a personal account of the early days of Cavity Quantum Electrodynamics before describing the main experiments performed at ENS during the last twenty years and concluding by a discussion comparing our work to other researches dealing with the control of single quantum particles.
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Affiliation(s)
- Serge Haroche
- Laboratoire Kastler Brossel de l'Ecole Normale Supérieure & Collège de France, Paris (France)
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85
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Neumeier L, Leib M, Hartmann MJ. Single-photon transistor in circuit quantum electrodynamics. PHYSICAL REVIEW LETTERS 2013; 111:063601. [PMID: 23971573 DOI: 10.1103/physrevlett.111.063601] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 06/06/2013] [Indexed: 06/02/2023]
Abstract
We introduce a circuit quantum electrodynamical setup for a "single-photon" transistor. In our approach photons propagate in two open transmission lines that are coupled via two interacting transmon qubits. The interaction is such that no photons are exchanged between the two transmission lines but a single photon in one line can completely block or enable the propagation of photons in the other line. High on-off ratios can be achieved for feasible experimental parameters. Our approach is inherently scalable as all photon pulses can have the same pulse shape and carrier frequency such that output signals of one transistor can be input signals for a consecutive transistor.
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Affiliation(s)
- Lukas Neumeier
- Technische Universität München, Physik Department, James Franck Straße, 85748 Garching, Germany.
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86
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Reduction of the radiative decay of atomic coherence in squeezed vacuum. Nature 2013; 499:62-5. [DOI: 10.1038/nature12264] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 05/01/2013] [Indexed: 11/08/2022]
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87
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Nigg SE, Girvin SM. Stabilizer quantum error correction toolbox for superconducting qubits. PHYSICAL REVIEW LETTERS 2013; 110:243604. [PMID: 25165923 DOI: 10.1103/physrevlett.110.243604] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Indexed: 06/03/2023]
Abstract
We present a general protocol for stabilizer operator measurements in a system of N superconducting qubits. Using the dispersive coupling between the qubits and the field of a resonator as well as single qubit rotations, we show how to encode the parity of an arbitrary subset of M ≤ N qubits, onto two quasiorthogonal coherent states of the resonator. Together with a fast cavity readout, this enables the efficient measurement of arbitrary stabilizer operators without locality constraints.
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Affiliation(s)
- Simon E Nigg
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - S M Girvin
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
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88
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Tasca DS, Rudnicki Ł, Gomes RM, Toscano F, Walborn SP. Reliable entanglement detection under coarse-grained measurements. PHYSICAL REVIEW LETTERS 2013; 110:210502. [PMID: 23745847 DOI: 10.1103/physrevlett.110.210502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Indexed: 06/02/2023]
Abstract
We derive reliable entanglement witnesses for coarse-grained measurements on continuous variable systems. These witnesses never return a "false positive" for identification of entanglement, under any degree of coarse graining. We show that even in the case of Gaussian states, entanglement witnesses based on the Shannon entropy can outperform those based on variances. We apply our results to experimental identification of spatial entanglement of photon pairs.
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Affiliation(s)
- D S Tasca
- SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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