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Agrawal A, Dixit AV, Roy T, Chakram S, He K, Naik RK, Schuster DI, Chou A. Stimulated Emission of Signal Photons from Dark Matter Waves. PHYSICAL REVIEW LETTERS 2024; 132:140801. [PMID: 38640371 DOI: 10.1103/physrevlett.132.140801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 01/26/2024] [Indexed: 04/21/2024]
Abstract
The manipulation of quantum states of light has resulted in significant advancements in both dark matter searches and gravitational wave detectors. Current dark matter searches operating in the microwave frequency range use nearly quantum-limited amplifiers. Future high frequency searches will use photon counting techniques to evade the standard quantum limit. We present a signal enhancement technique that utilizes a superconducting qubit to prepare a superconducting microwave cavity in a nonclassical Fock state and stimulate the emission of a photon from a dark matter wave. By initializing the cavity in an |n=4⟩ Fock state, we demonstrate a quantum enhancement technique that increases the signal photon rate and hence also the dark matter scan rate each by a factor of 2.78. Using this technique, we conduct a dark photon search in a band around 5.965 GHz (24.67 μeV), where the kinetic mixing angle ε≥4.35×10^{-13} is excluded at the 90% confidence level.
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Affiliation(s)
- Ankur Agrawal
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Akash V Dixit
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Tanay Roy
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Srivatsan Chakram
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Kevin He
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Ravi K Naik
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - David I Schuster
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Aaron Chou
- Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
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2
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Vivek G, Mondal D, Sinha S. Nonequilibrium dynamics of the Jaynes-Cummings dimer. Phys Rev E 2023; 108:054116. [PMID: 38115501 DOI: 10.1103/physreve.108.054116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/16/2023] [Indexed: 12/21/2023]
Abstract
We investigate the nonequilibrium dynamics of a Josephson-coupled Jaynes-Cummings dimer in the presence of Kerr nonlinearity, which can be realized in the cavity and circuit quantum electrodynamics systems. The semiclassical dynamics is analyzed systematically to chart out a variety of photonic Josephson oscillations and their regime of stability. Different types of transitions between the dynamical states lead to the self-trapping phenomenon, which results in photon population imbalance between the two cavities. We also study the dynamics quantum mechanically to identify characteristic features of different steady states and to explore fascinating quantum effects, such as spin dephasing, phase fluctuation, and revival phenomena of the photon field, as well as the entanglement of spin qubits. For a particular "self-trapped" state, the mutual information between the atomic qubits exhibits a direct correlation with the photon population imbalance, which is promising for generating photon mediated entanglement between two non interacting qubits in a controlled manner. Under a sudden quench from stable to unstable regime, the photon distribution exhibits phase space mixing with a rapid loss of coherence, resembling a thermal state. Finally, we discuss the relevance of the new results in experiments, which can have applications in quantum information processing and quantum technologies.
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Affiliation(s)
- G Vivek
- Indian Institute of Science Education and Research-Kolkata, Mohanpur, Nadia-741246, India
| | - Debabrata Mondal
- Indian Institute of Science Education and Research-Kolkata, Mohanpur, Nadia-741246, India
| | - S Sinha
- Indian Institute of Science Education and Research-Kolkata, Mohanpur, Nadia-741246, India
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3
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Cerisola F, Mayo F, Roncaglia AJ. A Wigner Quasiprobability Distribution of Work. ENTROPY (BASEL, SWITZERLAND) 2023; 25:1439. [PMID: 37895560 PMCID: PMC10606729 DOI: 10.3390/e25101439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/06/2023] [Accepted: 10/08/2023] [Indexed: 10/29/2023]
Abstract
In this article, we introduce a quasiprobability distribution of work that is based on the Wigner function. This proposal rests on the idea that the work conducted on an isolated system can be coherently measured by coupling the system to a quantum measurement apparatus. In this way, a quasiprobability distribution of work can be defined in terms of the Wigner function of the apparatus. This quasidistribution contains the information of the work statistics and also holds a clear operational definition that can be directly measured in a real experiment. Moreover, it is shown that the presence of quantum coherence in the energy eigenbasis is related with the appearance of features related to non-classicality in the Wigner function such as negativity and interference fringes. On the other hand, from this quasiprobability distribution, it is straightforward to obtain the standard two-point measurement probability distribution of work and also the difference in average energy for initial states with coherences.
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Affiliation(s)
- Federico Cerisola
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires C1428EGA, Argentina; (F.M.); (A.J.R.)
- Instituto de Física de Buenos Aires (IFIBA), CONICET—Universidad de Buenos Aires, Buenos Aires C1121A6B, Argentina
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK
| | - Franco Mayo
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires C1428EGA, Argentina; (F.M.); (A.J.R.)
- Instituto de Física de Buenos Aires (IFIBA), CONICET—Universidad de Buenos Aires, Buenos Aires C1121A6B, Argentina
| | - Augusto J. Roncaglia
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires C1428EGA, Argentina; (F.M.); (A.J.R.)
- Instituto de Física de Buenos Aires (IFIBA), CONICET—Universidad de Buenos Aires, Buenos Aires C1121A6B, Argentina
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4
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Teoh JD, Winkel P, Babla HK, Chapman BJ, Claes J, de Graaf SJ, Garmon JWO, Kalfus WD, Lu Y, Maiti A, Sahay K, Thakur N, Tsunoda T, Xue SH, Frunzio L, Girvin SM, Puri S, Schoelkopf RJ. Dual-rail encoding with superconducting cavities. Proc Natl Acad Sci U S A 2023; 120:e2221736120. [PMID: 37801473 PMCID: PMC10576063 DOI: 10.1073/pnas.2221736120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 08/07/2023] [Indexed: 10/08/2023] Open
Abstract
The design of quantum hardware that reduces and mitigates errors is essential for practical quantum error correction (QEC) and useful quantum computation. To this end, we introduce the circuit-Quantum Electrodynamics (QED) dual-rail qubit in which our physical qubit is encoded in the single-photon subspace, [Formula: see text], of two superconducting microwave cavities. The dominant photon loss errors can be detected and converted into erasure errors, which are in general much easier to correct. In contrast to linear optics, a circuit-QED implementation of the dual-rail code offers unique capabilities. Using just one additional transmon ancilla per dual-rail qubit, we describe how to perform a gate-based set of universal operations that includes state preparation, logical readout, and parametrizable single and two-qubit gates. Moreover, first-order hardware errors in the cavities and the transmon can be detected and converted to erasure errors in all operations, leaving background Pauli errors that are orders of magnitude smaller. Hence, the dual-rail cavity qubit exhibits a favorable hierarchy of error rates and is expected to perform well below the relevant QEC thresholds with today's coherence times.
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Affiliation(s)
- James D. Teoh
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Patrick Winkel
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Harshvardhan K. Babla
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Benjamin J. Chapman
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Jahan Claes
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Stijn J. de Graaf
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - John W. O. Garmon
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - William D. Kalfus
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Yao Lu
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Aniket Maiti
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Kaavya Sahay
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Neel Thakur
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Takahiro Tsunoda
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Sophia H. Xue
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Luigi Frunzio
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Steven M. Girvin
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Shruti Puri
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
| | - Robert J. Schoelkopf
- Department of Applied Physics, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
- Yale Quantum Institute, Yale University, New Haven, CT06511
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5
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de Paula MVS, Sinesio WWT, Dodonov AV. Ancilla-Assisted Generation of Photons from Vacuum via Time-Modulation of Extracavity Qubit. ENTROPY (BASEL, SWITZERLAND) 2023; 25:901. [PMID: 37372245 DOI: 10.3390/e25060901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 05/14/2023] [Accepted: 05/22/2023] [Indexed: 06/29/2023]
Abstract
We propose a scheme for the generation of photons from a vacuum via time-modulation of a quantum system indirectly coupled to the cavity field through some ancilla quantum subsystem. We consider the simplest case when the modulation is applied to an artificial two-level atom (we call 't-qubit', that can be located even outside the cavity), while the ancilla is a stationary qubit coupled via the dipole interaction both to the cavity and t-qubit. We find that tripartite entangled states with a small number of photons can be generated from the system ground state under resonant modulations, even when the t-qubit is far detuned from both the ancilla and the cavity, provided its bare and modulation frequencies are properly adjusted. We attest our approximate analytic results by numeric simulations and show that photon generation from vacuum persists in the presence of common dissipation mechanisms.
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Affiliation(s)
- Marcos V S de Paula
- Institute of Physics, University of Brasilia, Caixa Postal 04455, Brasilia 70910-900, DF, Brazil
| | - William W T Sinesio
- Institute of Physics, University of Brasilia, Caixa Postal 04455, Brasilia 70910-900, DF, Brazil
| | - Alexandre V Dodonov
- Institute of Physics, University of Brasilia, Caixa Postal 04455, Brasilia 70910-900, DF, Brazil
- International Center of Physics, Institute of Physics, University of Brasilia, Brasilia 70910-900, DF, Brazil
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6
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Del Pino J, Zilberberg O. Dynamical Gauge Fields with Bosonic Codes. PHYSICAL REVIEW LETTERS 2023; 130:171901. [PMID: 37172225 DOI: 10.1103/physrevlett.130.171901] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 03/31/2023] [Accepted: 04/04/2023] [Indexed: 05/14/2023]
Abstract
The quantum simulation of dynamical gauge field theories offers the opportunity to study complex high-energy physics with controllable low-energy devices. For quantum computation, bosonic codes promise robust error correction that exploits multiparticle redundancy in bosons. Here, we demonstrate how bosonic codes can be used to simulate dynamical gauge fields. We encode both matter and dynamical gauge fields in a network of resonators that are coupled via three-wave mixing. The mapping to a Z_{2} dynamical lattice gauge theory is established when the gauge resonators operate as Schrödinger cat states. We explore the optimal conditions under which the system preserves the required gauge symmetries. Our findings promote realizing high-energy models using bosonic codes.
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Affiliation(s)
- Javier Del Pino
- Institute for Theoretical Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Oded Zilberberg
- Department of Physics, University of Konstanz, 78464 Konstanz, Germany
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7
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Liu F. Semi-Markov processes in open quantum systems: Connections and applications in counting statistics. Phys Rev E 2022; 106:054152. [PMID: 36559413 DOI: 10.1103/physreve.106.054152] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 11/02/2022] [Indexed: 06/17/2023]
Abstract
Using the age-structure formalism, we definitely establish connections between semi-Markov processes and the dynamics of open quantum systems that satisfy the Markov quantum master equations. A generalized Feynman-Kac formula of the semi-Markov processes is also proposed. In addition to inheriting all statistical properties possessed by the piecewise deterministic processes of wave functions, the semi-Markov processes show their unique advantages in quantum counting statistics. Compared with the conventional method of the tilted quantum master equation, they can be applied to more general counting quantities. In particular, the terms involved in the method have precise probability meanings. We use a driven two-level quantum system to exemplify these results.
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Affiliation(s)
- Fei Liu
- School of Physics, Beihang University, Beijing 100191, China
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8
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Andersen AL, Mølmer K. Quantum Nondemolition Measurements of Moving Target States. PHYSICAL REVIEW LETTERS 2022; 129:120402. [PMID: 36179166 DOI: 10.1103/physrevlett.129.120402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 08/26/2022] [Indexed: 06/16/2023]
Abstract
We present a protocol for probing the state of a quantum system by its resonant coupling and entanglement with a meter system. By continuous measurement of a time evolving meter observable, we infer the evolution of the entangled systems and, ultimately, the state and dynamics of the system of interest. The photon number in a cavity field is thus resolved by simulated monitoring of the Rabi oscillations of a resonantly coupled two-level system, and we propose to regard this as a practical extension of quantum nondemolition measurements with applications in quantum metrology and quantum computing.
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Affiliation(s)
- Anton L Andersen
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
| | - Klaus Mølmer
- Aarhus Institute of Advanced Studies, Aarhus University, Høegh-Guldbergs Gade 6B, DK-8000 Aarhus C, Denmark and Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
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9
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Pashin D, Bastrakova M, Satanin A, Klenov N. Bifurcation Oscillator as an Advanced Sensor for Quantum State Control. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22176580. [PMID: 36081037 PMCID: PMC9460148 DOI: 10.3390/s22176580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 08/26/2022] [Accepted: 08/27/2022] [Indexed: 06/01/2023]
Abstract
We study bifurcation behavior of a high-quality (high-Q) Josephson oscillator coupled to a superconducting qubit. It is shown that the probability of capture into the state of dynamic equilibrium is sensitive to qubit states. On this basis we present a new measurement method for the superposition state of a qubit due to its influence on transition probabilities between oscillator levels located in the energy region near the classical separatrix. The quantum-mechanical behavior of a bifurcation oscillator is also studied, which makes it possible to understand the mechanism of "entanglement" of oscillator and qubit states during the measurement process. The optimal parameters of the driving current and the state of the oscillator are found for performing one-qubit gates with the required precision, when the influence on the qubit from measurement back-action is minimal. A measurement protocol for state populations of the qubit entangled with the oscillator is presented.
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Affiliation(s)
- Dmitrii Pashin
- Faculty of Physics, Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia
| | - Marina Bastrakova
- Faculty of Physics, Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia
- Russian Quantum Center, 143025 Moscow, Russia
| | - Arkady Satanin
- Higher School of Economics, Russia National Research University, 101000 Moscow, Russia
- Dukhov All-Russia Research Institute of Automatics, 101000 Moscow, Russia
| | - Nikolay Klenov
- Faculty of Physics, Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia
- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
- Science and Research Department, Moscow Technical University of Communication and Informatics, 111024 Moscow, Russia
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10
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Mylnikov VY, Potashin SO, Sokolovskii GS, Averkiev NS. Dissipative Phase Transition in Systems with Two-Photon Drive and Nonlinear Dissipation near the Critical Point. NANOMATERIALS 2022; 12:nano12152543. [PMID: 35893511 PMCID: PMC9332203 DOI: 10.3390/nano12152543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/15/2022] [Accepted: 07/21/2022] [Indexed: 11/16/2022]
Abstract
In this paper, we examine dissipative phase transition (DPT) near the critical point for a system with two-photon driving and nonlinear dissipations. The proposed mean-field theory, which explicitly takes into account quantum fluctuations, allowed us to describe properly the evolutionary dynamics of the system and to demonstrate new effects in its steady-state. We show that the presence of quantum fluctuations leads to a power-law dependence of the anomalous average at the phase transition point, with which the critical exponent is associated. Also, we investigate the effect of the quantum fluctuations on the critical point renormalization and demonstrate the existence of a two-photon pump “threshold”. It is noteworthy that the obtained results are in a good agreement with the numerical simulations.
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Affiliation(s)
- Valentin Yu. Mylnikov
- Ioffe Institute, 194021 St. Petersburg, Russia; (S.O.P.); (N.S.A.)
- Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
- Correspondence: (V.Y.M.); (G.S.S.)
| | | | - Grigorii S. Sokolovskii
- Ioffe Institute, 194021 St. Petersburg, Russia; (S.O.P.); (N.S.A.)
- Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia
- Correspondence: (V.Y.M.); (G.S.S.)
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11
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Deterministic Entanglement Swapping with Hybrid Discrete- and Continuous-Variable Systems. PHOTONICS 2022. [DOI: 10.3390/photonics9060368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The study of entanglement between discrete and continuous variables is an important theoretical and experimental topic in quantum information processing, for which entanglement swapping is one of the interesting elements. Entanglement swapping allows two particles without interacting with each other in any way, to form an entangled state by the action of another pair of entangled particles. In this paper, we propose an experimentally feasible scheme to realize deterministic entanglement swapping in the hybrid system with discrete and continuous variables. The process is achieved by preparing two pairs of entangled states, each is formed by a qubit and two quasi-orthogonal coherent state elements of a cavity, performing a Bell-state analysis through nonlocal operations on the continuous variable states of the two cavities, and projecting the two qubits into a maximally entangled state. The present scheme may be applied to other physical systems sustaining such hybrid discrete and continuous forms, providing a typical paradigm for entanglement manipulation through deterministic swapping operations.
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12
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Dixit AV, Chakram S, He K, Agrawal A, Naik RK, Schuster DI, Chou A. Searching for Dark Matter with a Superconducting Qubit. PHYSICAL REVIEW LETTERS 2021; 126:141302. [PMID: 33891438 DOI: 10.1103/physrevlett.126.141302] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 02/05/2021] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
Detection mechanisms for low mass bosonic dark matter candidates, such as the axion or hidden photon, leverage potential interactions with electromagnetic fields, whereby the dark matter (of unknown mass) on rare occasion converts into a single photon. Current dark matter searches operating at microwave frequencies use a resonant cavity to coherently accumulate the field sourced by the dark matter and a near standard quantum limited (SQL) linear amplifier to read out the cavity signal. To further increase sensitivity to the dark matter signal, sub-SQL detection techniques are required. Here we report the development of a novel microwave photon counting technique and a new exclusion limit on hidden photon dark matter. We operate a superconducting qubit to make repeated quantum nondemolition measurements of cavity photons and apply a hidden Markov model analysis to reduce the noise to 15.7 dB below the quantum limit, with overall detector performance limited by a residual background of real photons. With the present device, we perform a hidden photon search and constrain the kinetic mixing angle to ε≤1.68×10^{-15} in a band around 6.011 GHz (24.86 μeV) with an integration time of 8.33 s. This demonstrated noise reduction technique enables future dark matter searches to be sped up by a factor of 1,300. By coupling a qubit to an arbitrary quantum sensor, more general sub-SQL metrology is possible with the techniques presented in this Letter.
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Affiliation(s)
- Akash V Dixit
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Srivatsan Chakram
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Kevin He
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Ankur Agrawal
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
- Kavli Institute for Cosmological Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Ravi K Naik
- Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
| | - David I Schuster
- James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Aaron Chou
- Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
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13
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Van Regemortel M, Cian ZP, Seif A, Dehghani H, Hafezi M. Entanglement Entropy Scaling Transition under Competing Monitoring Protocols. PHYSICAL REVIEW LETTERS 2021; 126:123604. [PMID: 33834828 DOI: 10.1103/physrevlett.126.123604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 01/05/2021] [Accepted: 03/01/2021] [Indexed: 06/12/2023]
Abstract
Dissipation generally leads to the decoherence of a quantum state. In contrast, numerous recent proposals have illustrated that dissipation can also be tailored to stabilize many-body entangled quantum states. While the focus of these works has been primarily on engineering the nonequilibrium steady state, we investigate the buildup of entanglement in the quantum trajectories. Specifically, we analyze the competition between two different dissipation channels arising from two incompatible continuous monitoring protocols. The first protocol locks the phase of neighboring sites upon registering a quantum jump, thereby generating a long-range entanglement through the system, while the second destroys the coherence via a dephasing mechanism. By studying the unraveling of stochastic quantum trajectories associated with the continuous monitoring protocols, we present a transition for the scaling of the averaged trajectory entanglement entropies, from critical scaling to area-law behavior. Our work provides an alternative perspective on the measurement-induced phase transition: the measurement can be viewed as monitoring and registering quantum jumps, offering an intriguing extension of these phase transitions through the long-established realm of quantum optics.
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Affiliation(s)
- Mathias Van Regemortel
- Joint Quantum Institute, College Park, 20742 Maryland, USA and The Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, 20742 Maryland, USA
| | - Ze-Pei Cian
- Joint Quantum Institute, College Park, 20742 Maryland, USA and The Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, 20742 Maryland, USA
| | - Alireza Seif
- Joint Quantum Institute, College Park, 20742 Maryland, USA and The Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, 20742 Maryland, USA
| | - Hossein Dehghani
- Joint Quantum Institute, College Park, 20742 Maryland, USA and The Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, 20742 Maryland, USA
| | - Mohammad Hafezi
- Joint Quantum Institute, College Park, 20742 Maryland, USA and The Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, 20742 Maryland, USA
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14
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Tyagi G, Panigrahi PK. Photon added cat state: phase space structure and statistics. OPTICS LETTERS 2021; 46:1177-1180. [PMID: 33649686 DOI: 10.1364/ol.415713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
The phase space structure and statistics of the photon added cat state are studied in the state's general form. Photon addition leads to a π phase shift at the origin in the observed phase space interference of the Wigner function, which may serve as an error syndrome detector. The maxima and minima of the sub-Planck tiles in the phase space of the kitten state are interchanged after photon addition, leading to their orthogonality. Interestingly, photon addition to the Yurke-Stoler state characterized by Poissonian statistics leads to a sub-Poissonian distribution, which may find potential use in quantum noise reduction.
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15
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Gertler JM, Baker B, Li J, Shirol S, Koch J, Wang C. Protecting a bosonic qubit with autonomous quantum error correction. Nature 2021; 590:243-248. [PMID: 33568826 DOI: 10.1038/s41586-021-03257-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 11/18/2020] [Indexed: 01/31/2023]
Abstract
To build a universal quantum computer from fragile physical qubits, effective implementation of quantum error correction (QEC)1 is an essential requirement and a central challenge. Existing demonstrations of QEC are based on an active schedule of error-syndrome measurements and adaptive recovery operations2,3,4,5,6,7 that are hardware intensive and prone to introducing and propagating errors. In principle, QEC can be realized autonomously and continuously by tailoring dissipation within the quantum system1,8,9,10,11,12,13,14, but so far it has remained challenging to achieve the specific form of dissipation required to counter the most prominent errors in a physical platform. Here we encode a logical qubit in Schrödinger cat-like multiphoton states15 of a superconducting cavity, and demonstrate a corrective dissipation process that stabilizes an error-syndrome operator: the photon number parity. Implemented with continuous-wave control fields only, this passive protocol protects the quantum information by autonomously correcting single-photon-loss errors and boosts the coherence time of the bosonic qubit by over a factor of two. Notably, QEC is realized in a modest hardware setup with neither high-fidelity readout nor fast digital feedback, in contrast to the technological sophistication required for prior QEC demonstrations. Compatible with additional phase-stabilization and fault-tolerant techniques16,17,18, our experiment suggests quantum dissipation engineering as a resource-efficient alternative or supplement to active QEC in future quantum computing architectures.
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Affiliation(s)
- Jeffrey M Gertler
- Department of Physics, University of Massachusetts Amherst, Amherst, MA, USA
| | - Brian Baker
- Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA
| | - Juliang Li
- Department of Physics, University of Massachusetts Amherst, Amherst, MA, USA
| | - Shruti Shirol
- Department of Physics, University of Massachusetts Amherst, Amherst, MA, USA
| | - Jens Koch
- Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA
| | - Chen Wang
- Department of Physics, University of Massachusetts Amherst, Amherst, MA, USA.
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16
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Cai W, Ma Y, Wang W, Zou CL, Sun L. Bosonic quantum error correction codes in superconducting quantum circuits. FUNDAMENTAL RESEARCH 2021. [DOI: 10.1016/j.fmre.2020.12.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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17
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Ma Y, Pan X, Cai W, Mu X, Xu Y, Hu L, Wang W, Wang H, Song YP, Yang ZB, Zheng SB, Sun L. Manipulating Complex Hybrid Entanglement and Testing Multipartite Bell Inequalities in a Superconducting Circuit. PHYSICAL REVIEW LETTERS 2020; 125:180503. [PMID: 33196232 DOI: 10.1103/physrevlett.125.180503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 09/23/2020] [Indexed: 06/11/2023]
Abstract
Quantum correlations in observables of multiple systems not only are of fundamental interest, but also play a key role in quantum information processing. As a signature of these correlations, the violation of Bell inequalities has not been demonstrated with multipartite hybrid entanglement involving both continuous and discrete variables. Here we create a five-partite entangled state with three superconducting transmon qubits and two photonic qubits, each encoded in the mesoscopic field of a microwave cavity. We reveal the quantum correlations among these distinct elements by joint Wigner tomography of the two cavity fields conditional on the detection of the qubits and by test of a five-partite Bell inequality. The measured Bell signal is 8.381±0.038, surpassing the bound of 8 for a four-partite entanglement imposed by quantum correlations by 10 standard deviations, demonstrating the genuine five-partite entanglement in a hybrid quantum system.
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Affiliation(s)
- Y Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - X Pan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - W Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - X Mu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y Xu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - L Hu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - W Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - H Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y P Song
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Zhen-Biao Yang
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Shi-Biao Zheng
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - L Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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18
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Xu Y, Ma Y, Cai W, Mu X, Dai W, Wang W, Hu L, Li X, Han J, Wang H, Song YP, Yang ZB, Zheng SB, Sun L. Demonstration of Controlled-Phase Gates between Two Error-Correctable Photonic Qubits. PHYSICAL REVIEW LETTERS 2020; 124:120501. [PMID: 32281851 DOI: 10.1103/physrevlett.124.120501] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 10/09/2019] [Accepted: 02/28/2020] [Indexed: 06/11/2023]
Abstract
To realize fault-tolerant quantum computing, it is necessary to store quantum information in logical qubits with error correction functions, realized by distributing a logical state among multiple physical qubits or by encoding it in the Hilbert space of a high-dimensional system. Quantum gate operations between these error-correctable logical qubits, which are essential for implementation of any practical quantum computational task, have not been experimentally demonstrated yet. Here we demonstrate a geometric method for realizing controlled-phase gates between two logical qubits encoded in photonic fields stored in cavities. The gates are realized by dispersively coupling an ancillary superconducting qubit to these cavities and driving it to make a cyclic evolution depending on the joint photonic state of the cavities, which produces a conditional geometric phase. We first realize phase gates for photonic qubits with the logical basis states encoded in two quasiorthogonal coherent states, which have important implications for continuous-variable-based quantum computation. Then we use this geometric method to implement a controlled-phase gate between two binomially encoded logical qubits, which have an error-correctable function.
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Affiliation(s)
- Y Xu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - W Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - X Mu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - W Dai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - W Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - L Hu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - X Li
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - J Han
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - H Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y P Song
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Zhen-Biao Yang
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Shi-Biao Zheng
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - L Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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19
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Hann CT, Zou CL, Zhang Y, Chu Y, Schoelkopf RJ, Girvin SM, Jiang L. Hardware-Efficient Quantum Random Access Memory with Hybrid Quantum Acoustic Systems. PHYSICAL REVIEW LETTERS 2019; 123:250501. [PMID: 31922763 DOI: 10.1103/physrevlett.123.250501] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Indexed: 06/10/2023]
Abstract
Hybrid quantum systems in which acoustic resonators couple to superconducting qubits are promising quantum information platforms. High quality factors and small mode volumes make acoustic modes ideal quantum memories, while the qubit-phonon coupling enables the initialization and manipulation of quantum states. We present a scheme for quantum computing with multimode quantum acoustic systems, and based on this scheme, propose a hardware-efficient implementation of a quantum random access memory (QRAM). Quantum information is stored in high-Q phonon modes, and couplings between modes are engineered by applying off-resonant drives to a transmon qubit. In comparison to existing proposals that involve directly exciting the qubit, this scheme can offer a substantial improvement in gate fidelity for long-lived acoustic modes. We show how these engineered phonon-phonon couplings can be used to access data in superposition according to the state of designated address modes-implementing a QRAM on a single chip.
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Affiliation(s)
- Connor T Hann
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Chang-Ling Zou
- Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
| | - Yaxing Zhang
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Yiwen Chu
- Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Robert J Schoelkopf
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA
| | - S M Girvin
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Liang Jiang
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA
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20
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Wang W, Han J, Yadin B, Ma Y, Ma J, Cai W, Xu Y, Hu L, Wang H, Song YP, Gu M, Sun L. Witnessing Quantum Resource Conversion within Deterministic Quantum Computation Using One Pure Superconducting Qubit. PHYSICAL REVIEW LETTERS 2019; 123:220501. [PMID: 31868406 DOI: 10.1103/physrevlett.123.220501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/22/2019] [Indexed: 06/10/2023]
Abstract
Deterministic quantum computation with one qubit (DQC1) is iconic in highlighting that exponential quantum speedup may be achieved with negligible entanglement. Its discovery catalyzed a heated study of general quantum resources, and various conjectures regarding their role in DQC1's performance advantage. Coherence and discord are prominent candidates, respectively, characterizing nonclassicality within localized and correlated systems. Here we realize DQC1 within a superconducting system, engineered such that the dynamics of coherence and discord can be tracked throughout its execution. We experimentally confirm that DQC1 acts as a resource converter, consuming coherence to generate discord during its operation. Our results highlight superconducting circuits as a promising platform for both realizing DQC1 and related algorithms, and experimentally characterizing resource dynamics within quantum protocols.
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Affiliation(s)
- W Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - J Han
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - B Yadin
- Atomic and Laser Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
| | - Y Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - J Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - W Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y Xu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - L Hu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - H Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y P Song
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Mile Gu
- School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639673, Republic of Singapore
- Complexity Institute, Nanyang Technological University, Singapore 639673, Republic of Singapore
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543, Republic of Singapore
| | - L Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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21
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Joo J, Lee CW, Kono S, Kim J. Logical measurement-based quantum computation in circuit-QED. Sci Rep 2019; 9:16592. [PMID: 31719588 PMCID: PMC6851091 DOI: 10.1038/s41598-019-52866-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 10/03/2019] [Indexed: 11/27/2022] Open
Abstract
We propose a new scheme of measurement-based quantum computation (MBQC) using an error-correcting code against photon-loss in circuit quantum electrodynamics. We describe a specific protocol of logical single-qubit gates given by sequential cavity measurements for logical MBQC and a generalised Schrödinger cat state is used for a continuous-variable (CV) logical qubit captured in a microwave cavity. To apply an error-correcting scheme on the logical qubit, we utilise a d-dimensional quantum system called a qudit. It is assumed that a three CV-qudit entangled state is initially prepared in three jointed cavities and the microwave qudit states are individually controlled, operated, and measured through a readout resonator coupled with an ancillary superconducting qubit. We then examine a practical approach of how to create the CV-qudit cluster state via a cross-Kerr interaction induced by intermediary superconducting qubits between neighbouring cavities under the Jaynes-Cummings Hamiltonian. This approach could be scalable for building 2D logical cluster states and therefore will pave a new pathway of logical MBQC in superconducting circuits toward fault-tolerant quantum computing.
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Affiliation(s)
- Jaewoo Joo
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul, 02455, Korea.
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, UK.
| | - Chang-Woo Lee
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul, 02455, Korea
- Department of Physics Education, Kongju National University, Gongju, 32588, South Korea
| | - Shingo Kono
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo, 153-8904, Japan
| | - Jaewan Kim
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul, 02455, Korea
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22
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van Dam SB, Cramer J, Taminiau TH, Hanson R. Multipartite Entanglement Generation and Contextuality Tests Using Nondestructive Three-Qubit Parity Measurements. PHYSICAL REVIEW LETTERS 2019; 123:050401. [PMID: 31491297 DOI: 10.1103/physrevlett.123.050401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Indexed: 06/10/2023]
Abstract
We report on the realization and application of nondestructive three-qubit parity measurements on nuclear spin qubits in diamond. We use high-fidelity quantum logic to map the parity of the joint state of three nuclear spin qubits onto an electronic spin qubit that acts as an ancilla, followed by a single-shot nondestructive readout of the ancilla combined with an electron spin echo to ensure outcome-independent evolution of the nuclear spins. Through the sequential application of three such parity measurements, we demonstrate the generation of genuine multipartite entangled states out of the maximally mixed state. Furthermore, we implement a single-shot version of the Greenberger-Horne-Zeilinger experiment that can generate a quantum versus classical contradiction in each run. Finally, we test a state-independent noncontextuality inequality in eight dimensions. The techniques and insights developed are relevant for fundamental tests as well as for quantum information protocols such as quantum error correction.
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Affiliation(s)
- S B van Dam
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands and Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - J Cramer
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands and Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - T H Taminiau
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands and Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - R Hanson
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands and Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
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23
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Abdo B, Bronn NT, Jinka O, Olivadese S, Córcoles AD, Adiga VP, Brink M, Lake RE, Wu X, Pappas DP, Chow JM. Active protection of a superconducting qubit with an interferometric Josephson isolator. Nat Commun 2019; 10:3154. [PMID: 31316071 PMCID: PMC6637130 DOI: 10.1038/s41467-019-11101-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 06/20/2019] [Indexed: 11/09/2022] Open
Abstract
Nonreciprocal microwave devices play critical roles in high-fidelity, quantum-nondemolition (QND) measurement schemes. They impose unidirectional routing of readout signals and protect the quantum systems from unwanted noise originated by the output chain. However, cryogenic circulators and isolators are disadvantageous in scalable superconducting architectures because they use magnetic materials and strong magnetic fields. Here, we realize an active isolator formed by coupling two nondegenerate Josephson mixers in an interferometric scheme and driving them with phase-shifted, same-frequency pumps. By incorporating our Josephson-based isolator into a superconducting qubit setup, we demonstrate fast, high-fidelity, QND measurements of the qubit while providing 20 dB of protection within a bandwidth of 10 MHz against amplified noise reflected off the Josephson amplifier in the output chain. A moderate reduction of 35% is observed in T2E when the Josephson-based isolator is turned on. Such a moderate degradation can be mitigated by minimizing heat dissipation in the pump lines.
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Affiliation(s)
- Baleegh Abdo
- IBM T. J. Watson Research Center, Yorktown Heights, New York, NY, 10598, USA.
| | - Nicholas T Bronn
- IBM T. J. Watson Research Center, Yorktown Heights, New York, NY, 10598, USA
| | - Oblesh Jinka
- IBM T. J. Watson Research Center, Yorktown Heights, New York, NY, 10598, USA
| | - Salvatore Olivadese
- IBM T. J. Watson Research Center, Yorktown Heights, New York, NY, 10598, USA
| | - Antonio D Córcoles
- IBM T. J. Watson Research Center, Yorktown Heights, New York, NY, 10598, USA
| | - Vivekananda P Adiga
- IBM T. J. Watson Research Center, Yorktown Heights, New York, NY, 10598, USA
| | - Markus Brink
- IBM T. J. Watson Research Center, Yorktown Heights, New York, NY, 10598, USA
| | - Russell E Lake
- National Institute of Standards and Technology, Boulder, CO, 80305, USA
- Bluefors Oy, Arinatie 10, 00370, Helsinki, Finland
| | - Xian Wu
- National Institute of Standards and Technology, Boulder, CO, 80305, USA
| | - David P Pappas
- National Institute of Standards and Technology, Boulder, CO, 80305, USA
| | - Jerry M Chow
- IBM T. J. Watson Research Center, Yorktown Heights, New York, NY, 10598, USA
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24
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To catch and reverse a quantum jump mid-flight. Nature 2019; 570:200-204. [DOI: 10.1038/s41586-019-1287-z] [Citation(s) in RCA: 132] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/04/2019] [Indexed: 11/08/2022]
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25
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Lebreuilly J, Aron C, Mora C. Stabilizing Arrays of Photonic Cat States via Spontaneous Symmetry Breaking. PHYSICAL REVIEW LETTERS 2019; 122:120402. [PMID: 30978066 DOI: 10.1103/physrevlett.122.120402] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Indexed: 06/09/2023]
Abstract
The controlled generation and the protection of entanglement is key to quantum simulation and quantum computation. At the single-mode level, protocols based on photonic cat states hold strong promise as they present unprecedentedly long-lived coherence and may be combined with powerful error correction schemes. Here, we demonstrate that robust ensembles of "many-body photonic cat states" can be generated in a Bose-Hubbard model with pair hopping via a spontaneous U(1) symmetry-breaking mechanism. We identify a parameter region where the ground state is a massively degenerate manifold consisting of local cat states which are factorized throughout the lattice and whose conserved individual parities can be used to make a register of qubits. This phenomenology occurs for arbitrary system sizes or geometries, as soon as long-range order is established, and it extends to driven-dissipative conditions. In the thermodynamic limit, it is related to a Mott insulator to pair-superfluid phase transition.
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Affiliation(s)
- José Lebreuilly
- Laboratoire Pierre Aigrain, École Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Université, Université Paris Diderot-Sorbonne Paris Cité, Paris 75005, France
| | - Camille Aron
- Laboratoire de Physique Théorique, École Normale Supérieure, CNRS, PSL University, Sorbonne Université, Paris 75005, France
- Instituut voor Theoretische Fysica, KU Leuven 3001, Belgium
| | - Christophe Mora
- Laboratoire Pierre Aigrain, École Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Université, Université Paris Diderot-Sorbonne Paris Cité, Paris 75005, France
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26
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Entanglement of bosonic modes through an engineered exchange interaction. Nature 2019; 566:509-512. [DOI: 10.1038/s41586-019-0970-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 01/17/2019] [Indexed: 11/08/2022]
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27
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Malekakhlagh M, Rodriguez AW. Quantum Rabi Model with Two-Photon Relaxation. PHYSICAL REVIEW LETTERS 2019; 122:043601. [PMID: 30768294 DOI: 10.1103/physrevlett.122.043601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Indexed: 06/09/2023]
Abstract
We study a cavity-QED setup consisting of a two-level system coupled to a single cavity mode with two-photon relaxation. The system dynamics is modeled via a Lindblad master equation consisting of the Rabi Hamiltonian and a two-photon dissipator. We show that an even-photon relaxation preserves the Z_{2} symmetry of the Rabi model, and provide a framework to study the corresponding non-Hermitian dynamics in the number-parity basis. We discuss the role of different terms in the two-photon dissipator and show how one can extend existing results for the closed Rabi spectrum to the open case. Furthermore, we characterize the role of the Z_{2} symmetry in the excitation-relaxation dynamics of the system as a function of light-matter coupling. Importantly, we observe that initial states with even-odd parity manifest qualitatively distinct transient and steady state behaviors, contrary to the Hermitian dynamics that is only sensitive to whether or not the initial state is parity invariant. Moreover, the parity-sensitive dynamical behavior is not a creature of ultrastrong coupling and is present even at weak coupling values.
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Affiliation(s)
- Moein Malekakhlagh
- Department of Electrical Engineering, Princeton University, New Jersey 08544, USA
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28
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Experimental repetitive quantum channel simulation. Sci Bull (Beijing) 2018; 63:1551-1557. [PMID: 36751075 DOI: 10.1016/j.scib.2018.11.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 11/17/2018] [Accepted: 11/19/2018] [Indexed: 11/22/2022]
Abstract
Universal control of quantum systems is a major goal to be achieved for quantum information processing, which demands thorough understanding of fundamental quantum mechanics and promises applications of quantum technologies. So far, most studies concentrate on ideally isolated quantum systems governed by unitary evolutions, while practical quantum systems are open and described by quantum channels due to their inevitable coupling to environment. Here, we experimentally simulate arbitrary quantum channels for an open quantum system, i.e. a single photonic qubit in a superconducting quantum circuit. The arbitrary channel simulation is achieved with minimum resource of only one ancilla qubit and measurement-based adaptive control. By repetitively implementing the quantum channel simulation, we realize an arbitrary Liouvillian for a continuous evolution of an open quantum system for the first time. Our experiment provides not only a testbed for understanding quantum noise and decoherence, but also a powerful tool for full control of practical open quantum systems.
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29
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Repeated multi-qubit readout and feedback with a mixed-species trapped-ion register. Nature 2018; 563:527-531. [DOI: 10.1038/s41586-018-0668-z] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 08/23/2018] [Indexed: 11/08/2022]
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30
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Rosenblum S, Reinhold P, Mirrahimi M, Jiang L, Frunzio L, Schoelkopf RJ. Fault-tolerant detection of a quantum error. Science 2018; 361:266-270. [PMID: 30026224 DOI: 10.1126/science.aat3996] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/22/2018] [Indexed: 11/02/2022]
Abstract
A critical component of any quantum error-correcting scheme is detection of errors by using an ancilla system. However, errors occurring in the ancilla can propagate onto the logical qubit, irreversibly corrupting the encoded information. We demonstrate a fault-tolerant error-detection scheme that suppresses spreading of ancilla errors by a factor of 5, while maintaining the assignment fidelity. The same method is used to prevent propagation of ancilla excitations, increasing the logical qubit dephasing time by an order of magnitude. Our approach is hardware-efficient, as it uses a single multilevel transmon ancilla and a cavity-encoded logical qubit, whose interaction is engineered in situ by using an off-resonant sideband drive. The results demonstrate that hardware-efficient approaches that exploit system-specific error models can yield advances toward fault-tolerant quantum computation.
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Affiliation(s)
- S Rosenblum
- Departments of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA. .,Yale Quantum Institute, Yale University, New Haven, CT 06520, USA
| | - P Reinhold
- Departments of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA.,Yale Quantum Institute, Yale University, New Haven, CT 06520, USA
| | - M Mirrahimi
- Yale Quantum Institute, Yale University, New Haven, CT 06520, USA.,QUANTIC team, INRIA de Paris, 2 Rue Simone Iff, 75012 Paris, France
| | - Liang Jiang
- Departments of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA.,Yale Quantum Institute, Yale University, New Haven, CT 06520, USA
| | - L Frunzio
- Departments of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA.,Yale Quantum Institute, Yale University, New Haven, CT 06520, USA
| | - R J Schoelkopf
- Departments of Applied Physics and Physics, Yale University, New Haven, CT 06511, USA.,Yale Quantum Institute, Yale University, New Haven, CT 06520, USA
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31
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Xu Y, Cai W, Ma Y, Mu X, Hu L, Chen T, Wang H, Song YP, Xue ZY, Yin ZQ, Sun L. Single-Loop Realization of Arbitrary Nonadiabatic Holonomic Single-Qubit Quantum Gates in a Superconducting Circuit. PHYSICAL REVIEW LETTERS 2018; 121:110501. [PMID: 30265093 DOI: 10.1103/physrevlett.121.110501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Indexed: 06/08/2023]
Abstract
Geometric phases are noise resilient, and thus provide a robust way towards high-fidelity quantum manipulation. Here we experimentally demonstrate arbitrary nonadiabatic holonomic single-qubit quantum gates for both a superconducting transmon qubit and a microwave cavity in a single-loop way. In both cases, an auxiliary state is utilized, and two resonant microwave drives are simultaneously applied with well-controlled but varying amplitudes and phases for the arbitrariness of the gate. The resulting gates on the transmon qubit achieve a fidelity of 0.996 characterized by randomized benchmarking and the ones on the cavity show an averaged fidelity of 0.978 based on a full quantum process tomography. In principle, a nontrivial two-qubit holonomic gate between the qubit and the cavity can also be realized based on our presented experimental scheme. Our experiment thus paves the way towards practical nonadiabatic holonomic quantum manipulation with both qubits and cavities in a superconducting circuit.
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Affiliation(s)
- Y Xu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - W Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - X Mu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - L Hu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Tao Chen
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, and School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
| | - H Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y P Song
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, 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
| | - Zhang-Qi Yin
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - L Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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32
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Qin L, Wang Z, Zhang C, Li XQ. Direct measurement of the quantum state of photons in a cavity. OPTICS EXPRESS 2018; 26:7034-7042. [PMID: 29609389 DOI: 10.1364/oe.26.007034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 12/18/2017] [Indexed: 06/08/2023]
Abstract
We propose a scheme to measure the quantum state of photons in a cavity. The proposal is based on the concept of quantum weak values and applies equally well to both the solid-state circuit and atomic cavity quantum electrodynamics (QED) systems. The proposed scheme allows us to access directly the superposition components in Fock state basis, rather than the Wigner function as usual in phase space. Moreover, the separate access feature held in the direct scheme does not require a global reconstruction for the quantum state, which provides a particular advantage beyond the conventional method of quantum state tomography.
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33
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Abstract
We show that the Dynamical Casimir Effect (DCE), realized on two multimode coplanar waveg-uide resonators, implements a gaussian boson sampler (GBS). The appropriate choice of the mirror acceleration that couples both resonators translates into the desired initial gaussian state and many-boson interference in a boson sampling network. In particular, we show that the proposed quantum simulator naturally performs a classically hard task, known as scattershot boson sampling. Our result unveils an unprecedented computational power of DCE, and paves the way for using DCE as a resource for quantum simulation.
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34
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A CNOT gate between multiphoton qubits encoded in two cavities. Nat Commun 2018; 9:652. [PMID: 29440766 PMCID: PMC5811561 DOI: 10.1038/s41467-018-03059-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 01/16/2018] [Indexed: 11/08/2022] Open
Abstract
Entangling gates between qubits are a crucial component for performing algorithms in quantum computers. However, any quantum algorithm must ultimately operate on error-protected logical qubits encoded in high-dimensional systems. Typically, logical qubits are encoded in multiple two-level systems, but entangling gates operating on such qubits are highly complex and have not yet been demonstrated. Here we realize a controlled NOT (CNOT) gate between two multiphoton qubits in two microwave cavities. In this approach, we encode a qubit in the high-dimensional space of a single cavity mode, rather than in multiple two-level systems. We couple two such encoded qubits together through a transmon, which is driven by an RF pump to apply the gate within 190 ns. This is two orders of magnitude shorter than the decoherence time of the transmon, enabling a high-fidelity gate operation. These results are an important step towards universal algorithms on error-corrected logical qubits.
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35
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Kapit E. Error-Transparent Quantum Gates for Small Logical Qubit Architectures. PHYSICAL REVIEW LETTERS 2018; 120:050503. [PMID: 29481172 DOI: 10.1103/physrevlett.120.050503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Indexed: 06/08/2023]
Abstract
One of the largest obstacles to building a quantum computer is gate error, where the physical evolution of the state of a qubit or group of qubits during a gate operation does not match the intended unitary transformation. Gate error stems from a combination of control errors and random single qubit errors from interaction with the environment. While great strides have been made in mitigating control errors, intrinsic qubit error remains a serious problem that limits gate fidelity in modern qubit architectures. Simultaneously, recent developments of small error-corrected logical qubit devices promise significant increases in logical state lifetime, but translating those improvements into increases in gate fidelity is a complex challenge. In this Letter, we construct protocols for gates on and between small logical qubit devices which inherit the parent device's tolerance to single qubit errors which occur at any time before or during the gate. We consider two such devices, a passive implementation of the three-qubit bit flip code, and the author's own [E. Kapit, Phys. Rev. Lett. 116, 150501 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.150501] very small logical qubit (VSLQ) design, and propose error-tolerant gate sets for both. The effective logical gate error rate in these models displays superlinear error reduction with linear increases in single qubit lifetime, proving that passive error correction is capable of increasing gate fidelity. Using a standard phenomenological noise model for superconducting qubits, we demonstrate a realistic, universal one- and two-qubit gate set for the VSLQ, with error rates an order of magnitude lower than those for same-duration operations on single qubits or pairs of qubits. These developments further suggest that incorporating small logical qubits into a measurement based code could substantially improve code performance.
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Affiliation(s)
- Eliot Kapit
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
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36
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Zhou S, Zhang M, Preskill J, Jiang L. Achieving the Heisenberg limit in quantum metrology using quantum error correction. Nat Commun 2018; 9:78. [PMID: 29311599 PMCID: PMC5758555 DOI: 10.1038/s41467-017-02510-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 12/05/2017] [Indexed: 11/30/2022] Open
Abstract
Quantum metrology has many important applications in science and technology, ranging from frequency spectroscopy to gravitational wave detection. Quantum mechanics imposes a fundamental limit on measurement precision, called the Heisenberg limit, which can be achieved for noiseless quantum systems, but is not achievable in general for systems subject to noise. Here we study how measurement precision can be enhanced through quantum error correction, a general method for protecting a quantum system from the damaging effects of noise. We find a necessary and sufficient condition for achieving the Heisenberg limit using quantum probes subject to Markovian noise, assuming that noiseless ancilla systems are available, and that fast, accurate quantum processing can be performed. When the sufficient condition is satisfied, a quantum error-correcting code can be constructed that suppresses the noise without obscuring the signal; the optimal code, achieving the best possible precision, can be found by solving a semidefinite program.
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Affiliation(s)
- Sisi Zhou
- Departments of Applied Physics and Physics, Yale University, New Haven, CT, 06511, USA.
- Yale Quantum Institute, Yale University, New Haven, CT, 06520, USA.
| | - Mengzhen Zhang
- Departments of Applied Physics and Physics, Yale University, New Haven, CT, 06511, USA
- Yale Quantum Institute, Yale University, New Haven, CT, 06520, USA
| | - John Preskill
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Liang Jiang
- Departments of Applied Physics and Physics, Yale University, New Haven, CT, 06511, USA.
- Yale Quantum Institute, Yale University, New Haven, CT, 06520, USA.
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37
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Ding S, Maslennikov G, Hablützel R, Matsukevich D. Cross-Kerr Nonlinearity for Phonon Counting. PHYSICAL REVIEW LETTERS 2017; 119:193602. [PMID: 29219528 DOI: 10.1103/physrevlett.119.193602] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Indexed: 06/07/2023]
Abstract
State measurement of a quantum harmonic oscillator is essential in quantum optics and quantum information processing. In a system of trapped ions, we experimentally demonstrate the projective measurement of the state of the ions' motional mode via an effective cross-Kerr coupling to another motional mode. This coupling is induced by the intrinsic nonlinearity of the Coulomb interaction between the ions. We spectroscopically resolve the frequency shift of the motional sideband of the first mode due to the presence of single phonons in the second mode and use it to reconstruct the phonon number distribution of the second mode.
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Affiliation(s)
- Shiqian Ding
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore
| | - Gleb Maslennikov
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore
| | - Roland Hablützel
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore
| | - Dzmitry Matsukevich
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117551 Singapore, Singapore
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38
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Ding S, Maslennikov G, Hablützel R, Loh H, Matsukevich D. Quantum Parametric Oscillator with Trapped Ions. PHYSICAL REVIEW LETTERS 2017; 119:150404. [PMID: 29077472 DOI: 10.1103/physrevlett.119.150404] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Indexed: 06/07/2023]
Abstract
A strong nonlinear coupling between harmonic oscillators is highly desirable for quantum information processing and quantum simulation, but is difficult to achieve in many physical systems. Here, we exploit the Coulomb interaction between two trapped ions to achieve strong nonlinear coupling between normal modes of motion at the single-phonon level. We experimentally demonstrate phonon up- and down-conversion and apply this coupling to directly measure the parity and Wigner functions of the ions' motional states. Our results represent the fully quantum operation of a degenerate parametric oscillator and hold promise for quantum computation schemes that involve continuous variables.
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Affiliation(s)
- Shiqian Ding
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore
| | - Gleb Maslennikov
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore
| | - Roland Hablützel
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore
| | - Huanqian Loh
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore
| | - Dzmitry Matsukevich
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117551 Singapore, Singapore
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39
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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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40
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Cohen J, Smith WC, Devoret MH, Mirrahimi M. Degeneracy-Preserving Quantum Nondemolition Measurement of Parity-Type Observables for Cat Qubits. PHYSICAL REVIEW LETTERS 2017; 119:060503. [PMID: 28949639 DOI: 10.1103/physrevlett.119.060503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Indexed: 06/07/2023]
Abstract
A central requirement for any quantum error correction scheme is the ability to perform quantum nondemolition measurements of an error syndrome, corresponding to a special symmetry property of the encoding scheme. It is in particular important that such a measurement does not introduce extra error mechanisms, not included in the error model of the correction scheme. In this Letter, we ensure such a robustness by designing an interaction with a measurement device that preserves the degeneracy of the measured observable. More precisely, we propose a scheme to perform continuous and quantum nondemolition measurement of photon-number parity in a microwave cavity. This corresponds to the error syndrome in a class of error correcting codes called the cat codes, which have recently proven to be efficient and versatile for quantum information processing. In our design, we exploit the strongly nonlinear Hamiltonian of a high-impedance Josephson circuit, coupling a high-Q cavity storage cavity mode to a low-Q readout one. By driving the readout resonator at its resonance, the phase of the reflected or transmitted signal carries directly exploitable information on parity-type observables for encoded cat qubits of the high-Q mode.
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Affiliation(s)
- Joachim Cohen
- QUANTIC project-team, INRIA Paris, 75012 Paris, France
| | - W Clarke Smith
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Michel H Devoret
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Mazyar Mirrahimi
- QUANTIC project-team, INRIA Paris, 75012 Paris, France
- Yale Quantum Institute, Yale University, New Haven, Connecticut 06520, USA
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41
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Li L, Zou CL, Albert VV, Muralidharan S, Girvin SM, Jiang L. Cat Codes with Optimal Decoherence Suppression for a Lossy Bosonic Channel. PHYSICAL REVIEW LETTERS 2017; 119:030502. [PMID: 28777607 DOI: 10.1103/physrevlett.119.030502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Indexed: 06/07/2023]
Abstract
We investigate cat codes that can correct multiple excitation losses and identify two types of logical errors: bit-flip errors due to excessive excitation loss and dephasing errors due to quantum backaction from the environment. We show that selected choices of logical subspace and coherent amplitude significantly reduce dephasing errors. The trade-off between the two major errors enables optimized performance of cat codes in terms of minimized decoherence. With high coupling efficiency, we show that one-way quantum repeaters with cat codes feature a boosted secure communication rate per mode when compared to conventional encoding schemes, showcasing the promising potential of quantum information processing with continuous variable quantum codes.
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Affiliation(s)
- Linshu Li
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Chang-Ling Zou
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Victor V Albert
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Sreraman Muralidharan
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, USA
| | - S M Girvin
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Liang Jiang
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06511, USA
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42
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Implementing a universal gate set on a logical qubit encoded in an oscillator. Nat Commun 2017; 8:94. [PMID: 28733580 PMCID: PMC5522494 DOI: 10.1038/s41467-017-00045-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 04/27/2017] [Indexed: 11/09/2022] Open
Abstract
A logical qubit is a two-dimensional subspace of a higher dimensional system, chosen such that it is possible to detect and correct the occurrence of certain errors. Manipulation of the encoded information generally requires arbitrary and precise control over the entire system. Whether based on multiple physical qubits or larger dimensional modes such as oscillators, the individual elements in realistic devices will always have residual interactions, which must be accounted for when designing logical operations. Here we demonstrate a holistic control strategy which exploits accurate knowledge of the Hamiltonian to manipulate a coupled oscillator-transmon system. We use this approach to realize high-fidelity (98.5%, inferred), decoherence-limited operations on a logical qubit encoded in a superconducting cavity resonator using four-component cat states. Our results show the power of applying numerical techniques to control linear oscillators and pave the way for utilizing their large Hilbert space as a resource in quantum information processing.A logical qubit is a two-dimensional subspace of a higher dimensional system, whose manipulation requires precise control over the whole system. Here the authors demonstrate a control strategy which exploits precise knowledge of the Hamiltonian to manipulate a coupled oscillator-transmon system.
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43
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Liu K, Xu Y, Wang W, Zheng SB, Roy T, Kundu S, Chand M, Ranadive A, Vijay R, Song Y, Duan L, Sun L. A twofold quantum delayed-choice experiment in a superconducting circuit. SCIENCE ADVANCES 2017; 3:e1603159. [PMID: 28508079 PMCID: PMC5419705 DOI: 10.1126/sciadv.1603159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 03/03/2017] [Indexed: 06/07/2023]
Abstract
Wave-particle complementarity lies at the heart of quantum mechanics. To illustrate this mysterious feature, Wheeler proposed the delayed-choice experiment, where a quantum system manifests the wave- or particle-like attribute, depending on the experimental arrangement, which is made after the system has entered the interferometer. In recent quantum delayed-choice experiments, these two complementary behaviors were simultaneously observed with a quantum interferometer in a superposition of being closed and open. We suggest and implement a conceptually different quantum delayed-choice experiment by introducing a which-path detector (WPD) that can simultaneously record and neglect the system's path information, but where the interferometer itself is classical. Our experiment is realized with a superconducting circuit, where a cavity acts as the WPD for an interfering qubit. Using this setup, we implement the first twofold delayed-choice experiment, which demonstrates that the system's behavior depends not only on the measuring device's configuration that can be chosen even after the system has been detected but also on whether we a posteriori erase or mark the which-path information, the latter of which cannot be revealed by previous quantum delayed-choice experiments. Our results represent the first demonstration of both counterintuitive features with the same experimental setup, significantly extending the concept of quantum delayed-choice experiment.
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Affiliation(s)
- 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
| | - Shi-Biao Zheng
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350116, China
| | - Tanay Roy
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Suman Kundu
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Madhavi Chand
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Arpit Ranadive
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Rajamani Vijay
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Yipu Song
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Luming Duan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Luyan Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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44
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Lecocq F, Ranzani L, Peterson GA, Cicak K, Simmonds RW, Teufel JD, Aumentado J. Nonreciprocal Microwave Signal Processing with a Field-Programmable Josephson Amplifier. PHYSICAL REVIEW APPLIED 2017; 7:10.1103/physrevapplied.7.024028. [PMID: 38501125 PMCID: PMC10947609 DOI: 10.1103/physrevapplied.7.024028] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
We report on the design and implementation of a field-programmable Josephson amplifier (FPJA)-a compact and lossless superconducting circuit that can be programmed in situ by a set of microwave drives to perform reciprocal and nonreciprocal frequency conversion and amplification. In this work, we demonstrate four modes of operation: frequency conversion (transmission of -0.5 dB, reflection of -30 dB), circulation (transmission of -0.5 dB, reflection of -30 dB, isolation of 30 dB), phase-preserving amplification (gain > 20 dB, one photon of added noise) and directional phase-preserving amplification (reflection of -10 dB, forward gain of 18 dB, reverse isolation of 8 dB, one photon of added noise). The system exhibits quantitative agreement with the theoretical prediction. Based on a gradiometric superconducting quantum-interference device with Nb / Al - AlO x / Nb Josephson junctions, the FPJA is first-order insensitive to flux noise and can be operated without magnetic shielding at low temperature. Owing to its flexible design and compatibility with existing superconducting fabrication techniques, the FPJA offers a straightforward route toward on-chip integration with superconducting quantum circuits such as qubits and microwave optomechanical systems.
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Affiliation(s)
- F. Lecocq
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - L. Ranzani
- Raytheon BBN Technologies, 10 Moulton Street, Cambridge, Massachusetts 02138, USA
| | - G. A. Peterson
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - K. Cicak
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - R. W. Simmonds
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - J. D. Teufel
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
| | - J. Aumentado
- National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA
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45
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Liu F, Xi J. Characteristic functions based on a quantum jump trajectory. Phys Rev E 2017; 94:062133. [PMID: 28085337 DOI: 10.1103/physreve.94.062133] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Indexed: 11/07/2022]
Abstract
Characteristic functions (CFs) provide a very efficient method for evaluating the probability density functions of stochastic thermodynamic quantities and investigating their statistical features in quantum master equations (QMEs). A conventional procedure for obtaining these functions is to resort to a first-principles approach; namely, the evolution equations of the CFs of the combined system and its environment are obtained and then projected into the degrees of freedom of the system. However, the QMEs can be unraveled by a quantum jump trajectory. Thermodynamic quantities such as the heat, work, and entropy production can be well defined along a trajectory. Hence, on the basis of the notion of a trajectory, can we straightforwardly derive these CFs, e.g., their evolution equations? This is essential to establish the self-contained stochastic thermodynamics of a QME. In this paper, we show that it is indeed plausible and also simple. Particularly, these equations are fully consistent with those obtained by the first-principles method. Our results have practical significance; they indicate that the quantum fluctuation relations could be verified by more realistic photocounting experiments.
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Affiliation(s)
- Fei Liu
- School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China
| | - Jingyi Xi
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
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46
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Transient chaos - a resolution of breakdown of quantum-classical correspondence in optomechanics. Sci Rep 2016; 6:35381. [PMID: 27748418 PMCID: PMC5066317 DOI: 10.1038/srep35381] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/21/2016] [Indexed: 11/20/2022] Open
Abstract
Recently, the phenomenon of quantum-classical correspondence breakdown was uncovered in optomechanics, where in the classical regime the system exhibits chaos but in the corresponding quantum regime the motion is regular - there appears to be no signature of classical chaos whatsoever in the corresponding quantum system, generating a paradox. We find that transient chaos, besides being a physically meaningful phenomenon by itself, provides a resolution. Using the method of quantum state diffusion to simulate the system dynamics subject to continuous homodyne detection, we uncover transient chaos associated with quantum trajectories. The transient behavior is consistent with chaos in the classical limit, while the long term evolution of the quantum system is regular. Transient chaos thus serves as a bridge for the quantum-classical transition (QCT). Strikingly, as the system transitions from the quantum to the classical regime, the average chaotic transient lifetime increases dramatically (faster than the Ehrenfest time characterizing the QCT for isolated quantum systems). We develop a physical theory to explain the scaling law.
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Ofek N, Petrenko A, Heeres R, Reinhold P, Leghtas Z, Vlastakis B, Liu Y, Frunzio L, Girvin SM, Jiang L, Mirrahimi M, Devoret MH, Schoelkopf RJ. Extending the lifetime of a quantum bit with error correction in superconducting circuits. Nature 2016; 536:441-5. [DOI: 10.1038/nature18949] [Citation(s) in RCA: 469] [Impact Index Per Article: 58.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 06/08/2016] [Indexed: 12/18/2022]
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Govenius J, Lake RE, Tan KY, Möttönen M. Detection of Zeptojoule Microwave Pulses Using Electrothermal Feedback in Proximity-Induced Josephson Junctions. PHYSICAL REVIEW LETTERS 2016; 117:030802. [PMID: 27472107 DOI: 10.1103/physrevlett.117.030802] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Indexed: 06/06/2023]
Abstract
We experimentally investigate and utilize electrothermal feedback in a microwave nanobolometer based on a normal-metal (Au_{x}Pd_{1-x}) nanowire with proximity-induced superconductivity. The feedback couples the temperature and the electrical degrees of freedom in the nanowire, which both absorbs the incoming microwave radiation, and transduces the temperature change into a radio-frequency electrical signal. We tune the feedback in situ and access both positive and negative feedback regimes with rich nonlinear dynamics. In particular, strong positive feedback leads to the emergence of two metastable electron temperature states in the millikelvin range. We use these states for efficient threshold detection of coherent 8.4 GHz microwave pulses containing approximately 200 photons on average, corresponding to 1.1×10^{-21} J≈7.0 meV of energy.
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Affiliation(s)
- J Govenius
- QCD Labs, COMP Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FIN-00076 Aalto, Finland
| | - R E Lake
- QCD Labs, COMP Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FIN-00076 Aalto, Finland
| | - K Y Tan
- QCD Labs, COMP Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FIN-00076 Aalto, Finland
| | - M Möttönen
- QCD Labs, COMP Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FIN-00076 Aalto, Finland
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49
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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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50
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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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