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Optical tomography dynamics induced by qubit-resonator interaction under intrinsic decoherence. Sci Rep 2022; 12:17162. [PMID: 36229509 PMCID: PMC9561708 DOI: 10.1038/s41598-022-21348-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 09/26/2022] [Indexed: 11/09/2022] Open
Abstract
A superconducting circuit with a qubit and a resonator coupled via a two-photon interaction is considered. When the resonator is initially in a superposition of coherent states, optical tomography and quantum coherence dynamics are examined in the context of intrinsic decoherence. The results reveal that optical tomography is a good quantifier of the quantum coherence produced by the qubit-resonator interaction. The effects of qubit-resonator detuning and intrinsic decoherence on the dynamics of optical tomography distributions for coherent and even coherent states are investigated. The dynamics of optical tomography distributions are highly dependent on detuning and intrinsic decoherence. Our numerical simulations reveal that there is a relation between the optical tomography and the generated quantum coherence. When the qubit-resonator detuning and intrinsic decoherence are augmented, the amplitude and intensity, as well as the structure of the optical tomography, change substantially.
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2
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Dressel J, Chantasri A, Jordan AN, Korotkov AN. Arrow of Time for Continuous Quantum Measurement. PHYSICAL REVIEW LETTERS 2017; 119:220507. [PMID: 29286799 DOI: 10.1103/physrevlett.119.220507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Indexed: 06/07/2023]
Abstract
We investigate the statistical arrow of time for a quantum system being monitored by a sequence of measurements. For a continuous qubit measurement example, we demonstrate that time-reversed evolution is always physically possible, provided that the measurement record is also negated. Despite this restoration of dynamical reversibility, a statistical arrow of time emerges, and may be quantified by the log-likelihood difference between forward and backward propagation hypotheses. We then show that such reversibility is a universal feature of nonprojective measurements, with forward or backward Janus measurement sequences that are time-reversed inverses of each other.
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Affiliation(s)
- Justin Dressel
- Institute for Quantum Studies, Chapman University, Orange, California 92866, USA
- Schmid College of Science and Technology, Chapman University, Orange, California 92866, USA
| | - Areeya Chantasri
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
- Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA
- Centre for Quantum Dynamics, Griffith University, Nathan QLD 4111, Australia
| | - Andrew N Jordan
- Institute for Quantum Studies, Chapman University, Orange, California 92866, USA
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA
- Center for Coherence and Quantum Optics, University of Rochester, Rochester, New York 14627, USA
| | - Alexander N Korotkov
- Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA
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3
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Takita M, Cross AW, Córcoles AD, Chow JM, Gambetta JM. Experimental Demonstration of Fault-Tolerant State Preparation with Superconducting Qubits. PHYSICAL REVIEW LETTERS 2017; 119:180501. [PMID: 29219563 DOI: 10.1103/physrevlett.119.180501] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Indexed: 06/07/2023]
Abstract
Robust quantum computation requires encoding delicate quantum information into degrees of freedom that are hard for the environment to change. Quantum encodings have been demonstrated in many physical systems by observing and correcting storage errors, but applications require not just storing information; we must accurately compute even with faulty operations. The theory of fault-tolerant quantum computing illuminates a way forward by providing a foundation and collection of techniques for limiting the spread of errors. Here we implement one of the smallest quantum codes in a five-qubit superconducting transmon device and demonstrate fault-tolerant state preparation. We characterize the resulting code words through quantum process tomography and study the free evolution of the logical observables. Our results are consistent with fault-tolerant state preparation in a protected qubit subspace.
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Affiliation(s)
- Maika Takita
- IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Andrew W Cross
- IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - A D Córcoles
- IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Jerry M Chow
- IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Jay M Gambetta
- IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
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4
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Wendin G. Quantum information processing with superconducting circuits: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:106001. [PMID: 28682303 DOI: 10.1088/1361-6633/aa7e1a] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
During the last ten years, superconducting circuits have passed from being interesting physical devices to becoming contenders for near-future useful and scalable quantum information processing (QIP). Advanced quantum simulation experiments have been shown with up to nine qubits, while a demonstration of quantum supremacy with fifty qubits is anticipated in just a few years. Quantum supremacy means that the quantum system can no longer be simulated by the most powerful classical supercomputers. Integrated classical-quantum computing systems are already emerging that can be used for software development and experimentation, even via web interfaces. Therefore, the time is ripe for describing some of the recent development of superconducting devices, systems and applications. As such, the discussion of superconducting qubits and circuits is limited to devices that are proven useful for current or near future applications. Consequently, the centre of interest is the practical applications of QIP, such as computation and simulation in Physics and Chemistry.
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Affiliation(s)
- G Wendin
- Department of Microtechnology and Nanoscience-MC2, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
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5
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Averin DV, Xu K, Zhong YP, Song C, Wang H, Han S. Suppression of Dephasing by Qubit Motion in Superconducting Circuits. PHYSICAL REVIEW LETTERS 2016; 116:010501. [PMID: 26799006 DOI: 10.1103/physrevlett.116.010501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Indexed: 06/05/2023]
Abstract
We suggest and demonstrate a protocol which suppresses the low-frequency dephasing by qubit motion, i.e., transfer of the logical qubit of information in a system of n≥2 physical qubits. The protocol requires only the nearest-neighbor coupling and is applicable to different qubit structures. Our analysis of its effectiveness against noises with arbitrary correlations, together with experiments using up to three superconducting qubits, shows that for the realistic uncorrelated noises, qubit motion increases the dephasing time of the logical qubit as √n. In general, the protocol provides a diagnostic tool for measurements of the noise correlations.
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Affiliation(s)
- D V Averin
- Department of Physics and Astronomy, Stony Brook University, SUNY, Stony Brook, New York 11794-3800, USA
| | - K Xu
- Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Y P Zhong
- Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - C Song
- Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - H Wang
- Department of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Siyuan Han
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
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6
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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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7
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Chen Y, Neill C, Roushan P, Leung N, Fang M, Barends R, Kelly J, Campbell B, Chen Z, Chiaro B, Dunsworth A, Jeffrey E, Megrant A, Mutus JY, O'Malley PJJ, Quintana CM, Sank D, Vainsencher A, Wenner J, White TC, Geller MR, Cleland AN, Martinis JM. Qubit Architecture with High Coherence and Fast Tunable Coupling. PHYSICAL REVIEW LETTERS 2014; 113:220502. [PMID: 25494061 DOI: 10.1103/physrevlett.113.220502] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Indexed: 06/04/2023]
Abstract
We introduce a superconducting qubit architecture that combines high-coherence qubits and tunable qubit-qubit coupling. With the ability to set the coupling to zero, we demonstrate that this architecture is protected from the frequency crowding problems that arise from fixed coupling. More importantly, the coupling can be tuned dynamically with nanosecond resolution, making this architecture a versatile platform with applications ranging from quantum logic gates to quantum simulation. We illustrate the advantages of dynamical coupling by implementing a novel adiabatic controlled-z gate, with a speed approaching that of single-qubit gates. Integrating coherence and scalable control, the introduced qubit architecture provides a promising path towards large-scale quantum computation and simulation.
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Affiliation(s)
- Yu Chen
- 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
| | - N Leung
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - M Fang
- 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
| | - J Kelly
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - B Campbell
- 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
| | - E Jeffrey
- 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 and Department of Materials, University of California, Santa Barbara, California 93106-5050, USA
| | - J Y Mutus
- 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 M Quintana
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - D Sank
- 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
| | - T C White
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - Michael R Geller
- Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602, USA
| | - A N Cleland
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
| | - John M Martinis
- Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
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8
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Pang S, Dressel J, Brun TA. Entanglement-assisted weak value amplification. PHYSICAL REVIEW LETTERS 2014; 113:030401. [PMID: 25083620 DOI: 10.1103/physrevlett.113.030401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Indexed: 06/03/2023]
Abstract
Large weak values have been used to amplify the sensitivity of a linear response signal for detecting changes in a small parameter, which has also enabled a simple method for precise parameter estimation. However, producing a large weak value requires a low postselection probability for an ancilla degree of freedom, which limits the utility of the technique. We propose an improvement to this method that uses entanglement to increase the efficiency. We show that by entangling and postselecting n ancillas, the postselection probability can be increased by a factor of n while keeping the weak value fixed (compared to n uncorrelated attempts with one ancilla), which is the optimal scaling with n that is expected from quantum metrology. Furthermore, we show the surprising result that the quantum Fisher information about the detected parameter can be almost entirely preserved in the postselected state, which allows the sensitive estimation to approximately saturate the relevant quantum Cramér-Rao bound. To illustrate this protocol we provide simple quantum circuits that can be implemented using current experimental realizations of three entangled qubits.
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Affiliation(s)
- Shengshi Pang
- Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, USA
| | - Justin Dressel
- Department of Electrical Engineering, University of California, Riverside, California 92521, USA
| | - Todd A Brun
- Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, USA
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