1
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Mimona MA, Mobarak MH, Ahmed E, Kamal F, Hasan M. Nanowires: Exponential speedup in quantum computing. Heliyon 2024; 10:e31940. [PMID: 38845958 PMCID: PMC11153239 DOI: 10.1016/j.heliyon.2024.e31940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 05/24/2024] [Accepted: 05/24/2024] [Indexed: 06/09/2024] Open
Abstract
This review paper examines the crucial role of nanowires in the field of quantum computing, highlighting their importance as versatile platforms for qubits and vital building blocks for creating fault-tolerant and scalable quantum information processing systems. Researchers are studying many categories of nanowires, including semiconductor, superconducting, and topological nanowires, to explore their distinct quantum features that play a role in creating various qubit designs. The paper explores the interdisciplinary character of quantum computing, combining the fields of quantum physics and materials science. This text highlights the significance of quantum gate operations in manipulating qubits for computation, thus creating the toolbox of quantum algorithms. The paper emphasizes the key research areas in quantum technology, such as entanglement engineering, quantum error correction, and a wide range of applications spanning from encryption to climate change modeling. The research highlights the importance of tackling difficulties related to decoding mitigation, error correction, and hardware scalability to fully utilize the transformative potential of quantum computing in scientific, technical, and computational fields.
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Affiliation(s)
- Mariam Akter Mimona
- Department of Computer Science & Engineering, IUBAT-International University of Business Agriculture and Technology, Bangladesh
| | - Md Hosne Mobarak
- Department of Mechanical Engineering, IUBAT-International University of Business Agriculture and Technology, Bangladesh
| | - Emtiuz Ahmed
- Department of Computer Science & Engineering, IUBAT-International University of Business Agriculture and Technology, Bangladesh
| | - Farzana Kamal
- Department of Computer Science & Engineering, IUBAT-International University of Business Agriculture and Technology, Bangladesh
| | - Mehedi Hasan
- Department of Mechanical Engineering, IUBAT-International University of Business Agriculture and Technology, Bangladesh
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2
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Connolly T, Kurilovich PD, Diamond S, Nho H, Bøttcher CGL, Glazman LI, Fatemi V, Devoret MH. Coexistence of Nonequilibrium Density and Equilibrium Energy Distribution of Quasiparticles in a Superconducting Qubit. PHYSICAL REVIEW LETTERS 2024; 132:217001. [PMID: 38856268 DOI: 10.1103/physrevlett.132.217001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 08/10/2023] [Accepted: 03/21/2024] [Indexed: 06/11/2024]
Abstract
The density of quasiparticles typically observed in superconducting qubits exceeds the value expected in equilibrium by many orders of magnitude. Can this out-of-equilibrium quasiparticle density still possess an energy distribution in equilibrium with the phonon bath? Here, we answer this question affirmatively by measuring the thermal activation of charge-parity switching in a transmon qubit with a difference in superconducting gap on the two sides of the Josephson junction. We then demonstrate how the gap asymmetry of the device can be exploited to manipulate its parity.
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Affiliation(s)
- Thomas Connolly
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Pavel D Kurilovich
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Spencer Diamond
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Heekun Nho
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Charlotte G L Bøttcher
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Leonid I Glazman
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Valla Fatemi
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - Michel H Devoret
- Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
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3
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Atalaya J, Opremcak A, Nersisyan A, Lee K, Korotkov AN. Measurement of Small Photon Numbers in Circuit QED Resonators. PHYSICAL REVIEW LETTERS 2024; 132:203601. [PMID: 38829075 DOI: 10.1103/physrevlett.132.203601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 04/09/2024] [Indexed: 06/05/2024]
Abstract
Off-resonant interaction of fluctuating photons in a resonator with a qubit increases the qubit dephasing rate. We use this effect to measure a small average number of intracavity photons that are coherently or thermally driven. For spectral resolution, we do this by subjecting the qubit to a Carr-Purcell-Meiboom-Gill sequence and record the qubit dephasing rate for various periods between qubit π pulses. The recorded data is then analyzed with formulas for the photon-induced dephasing rate derived for the non-Gaussian noise regime with an arbitrary ratio of the resonator dispersive shift to decay rate. We show that the presented Carr-Purcell-Meiboom-Gill dephasing rate formulas agree well with experimental results and demonstrate measurement of thermal and coherent photon populations at the level of a few 10^{-4}.
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Affiliation(s)
- Juan Atalaya
- Google Quantum AI, Santa Barbara, California 93111, USA
| | - Alex Opremcak
- Google Quantum AI, Santa Barbara, California 93111, USA
| | - Ani Nersisyan
- Google Quantum AI, Santa Barbara, California 93111, USA
| | - Kenny Lee
- Google Quantum AI, Santa Barbara, California 93111, USA
| | - Alexander N Korotkov
- Google Quantum AI, Santa Barbara, California 93111, USA
- Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA
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4
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Kono S, Pan J, Chegnizadeh M, Wang X, Youssefi A, Scigliuzzo M, Kippenberg TJ. Mechanically induced correlated errors on superconducting qubits with relaxation times exceeding 0.4 ms. Nat Commun 2024; 15:3950. [PMID: 38729959 PMCID: PMC11087564 DOI: 10.1038/s41467-024-48230-3] [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: 07/06/2023] [Accepted: 04/24/2024] [Indexed: 05/12/2024] Open
Abstract
Superconducting qubits are among the most advanced candidates for achieving fault-tolerant quantum computing. Despite recent significant advancements in the qubit lifetimes, the origin of the loss mechanism for state-of-the-art qubits is still subject to investigation. Furthermore, the successful implementation of quantum error correction requires negligible correlated errors between qubits. Here, we realize long-lived superconducting transmon qubits that exhibit fluctuating lifetimes, averaging 0.2 ms and exceeding 0.4 ms - corresponding to quality factors above 5 million and 10 million, respectively. We then investigate their dominant error mechanism. By introducing novel time-resolved error measurements that are synchronized with the operation of the pulse tube cooler in a dilution refrigerator, we find that mechanical vibrations from the pulse tube induce nonequilibrium dynamics in highly coherent qubits, leading to their correlated bit-flip errors. Our findings not only deepen our understanding of the qubit error mechanisms but also provide valuable insights into potential error-mitigation strategies for achieving fault tolerance by decoupling superconducting qubits from their mechanical environments.
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Affiliation(s)
- Shingo Kono
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland.
| | - Jiahe Pan
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Mahdi Chegnizadeh
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Xuxin Wang
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Amir Youssefi
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Marco Scigliuzzo
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Tobias J Kippenberg
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland.
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5
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Huai S, Bu K, Gu X, Zhang Z, An S, Yang X, Li Y, Cai T, Zheng Y. Fast joint parity measurement via collective interactions induced by stimulated emission. Nat Commun 2024; 15:3045. [PMID: 38589424 PMCID: PMC11001884 DOI: 10.1038/s41467-024-47379-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 03/29/2024] [Indexed: 04/10/2024] Open
Abstract
Parity detection is essential in quantum error correction. Error syndromes coded in parity are detected routinely by sequential CNOT gates. Here, different from the standard CNOT-gate based scheme, we propose a reliable joint parity measurement (JPM) scheme inspired by stimulated emission. By controlling the collective behavior between data qubits and syndrome qubit, we realize the parity detection and experimentally implement the weight-2 and weight-4 JPM scheme in a tunable coupling superconducting circuit, which shows comparable performance to the CNOT scheme. Moreover, with the aid of the coupling tunability in quantum system, this scheme can be further utilized for specific joint entangling state preparation (JEP) with high fidelity, such as multiqubit entangled state preparation for non-adjacent qubits. This strategy, combined with the superconducting qubit system with tunable couplers, reveals tremendous potential and applications in the surface code architecture without adding extra circuit elements. Besides, the method we develop here can readily be applied in large-scale quantum computation and quantum simulation.
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Affiliation(s)
- Sainan Huai
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Kunliang Bu
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Xiu Gu
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China.
| | - Zhenxing Zhang
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Shuoming An
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Xiaopei Yang
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Yuan Li
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
| | - Tianqi Cai
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China.
| | - Yicong Zheng
- Quantum Laboratory, Tencent, 518057, Shenzhen, Guangdong, China
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6
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Viotti L, Lombardo FC, Villar PI. Geometric Phase of a Transmon in a Dissipative Quantum Circuit. ENTROPY (BASEL, SWITZERLAND) 2024; 26:89. [PMID: 38275497 PMCID: PMC10814483 DOI: 10.3390/e26010089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 01/27/2024]
Abstract
Superconducting circuits reveal themselves as promising physical devices with multiple uses. Within those uses, the fundamental concept of the geometric phase accumulated by the state of a system shows up recurrently, as, for example, in the construction of geometric gates. Given this framework, we study the geometric phases acquired by a paradigmatic setup: a transmon coupled to a superconductor resonating cavity. We do so both for the case in which the evolution is unitary and when it is subjected to dissipative effects. These models offer a comprehensive quantum description of an anharmonic system interacting with a single mode of the electromagnetic field within a perfect or dissipative cavity, respectively. In the dissipative model, the non-unitary effects arise from dephasing, relaxation, and decay of the transmon coupled to its environment. Our approach enables a comparison of the geometric phases obtained in these models, leading to a thorough understanding of the corrections introduced by the presence of the environment.
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Affiliation(s)
- Ludmila Viotti
- The Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34151 Trieste, Italy
| | - Fernando C. Lombardo
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
- Instituto de Física de Buenos Aires (IFIBA), CONICET—Universidad de Buenos Aires, Buenos Aires 1428, Argentina
| | - Paula I. Villar
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
- Instituto de Física de Buenos Aires (IFIBA), CONICET—Universidad de Buenos Aires, Buenos Aires 1428, Argentina
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7
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Upadhyay R, Golubev DS, Chang YC, Thomas G, Guthrie A, Peltonen JT, Pekola JP. Microwave quantum diode. Nat Commun 2024; 15:630. [PMID: 38245544 PMCID: PMC10799849 DOI: 10.1038/s41467-024-44908-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 01/05/2024] [Indexed: 01/22/2024] Open
Abstract
The fragile nature of quantum circuits is a major bottleneck to scalable quantum applications. Operating at cryogenic temperatures, quantum circuits are highly vulnerable to amplifier backaction and external noise. Non-reciprocal microwave devices such as circulators and isolators are used for this purpose. These devices have a considerable footprint in cryostats, limiting the scalability of quantum circuits. As a proof-of-concept, here we report a compact microwave diode architecture, which exploits the non-linearity of a superconducting flux qubit. At the qubit degeneracy point we experimentally demonstrate a significant difference between the power levels transmitted in opposite directions. The observations align with the proposed theoretical model. At - 99 dBm input power, and near the qubit-resonator avoided crossing region, we report the transmission rectification ratio exceeding 90% for a 50 MHz wide frequency range from 6.81 GHz to 6.86 GHz, and over 60% for the 250 MHz range from 6.67 GHz to 6.91 GHz. The presented architecture is compact, and easily scalable towards multiple readout channels, potentially opening up diverse opportunities in quantum information, microwave read-out and optomechanics.
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Affiliation(s)
- Rishabh Upadhyay
- Pico group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland.
| | - Dmitry S Golubev
- Pico group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - Yu-Cheng Chang
- Pico group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - George Thomas
- Pico group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
- VTT Technical Research Centre of Finland Ltd, Tietotie 3, 02150, Espoo, Finland
| | - Andrew Guthrie
- Pico group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - Joonas T Peltonen
- Pico group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
| | - Jukka P Pekola
- Pico group, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076, Aalto, Finland
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8
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Kang YH, Lin ZP, Yang JQ, Wang Y, Song J, Yang ZB, Xia Y. Effective protocol for generating NOON states of resonator modes. OPTICS EXPRESS 2023; 31:42976-42994. [PMID: 38178402 DOI: 10.1364/oe.498836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 11/21/2023] [Indexed: 01/06/2024]
Abstract
We propose a protocol for the generation of NOON states of resonator modes. The physical model is composed of two Kerr-nonlinear resonators and a four-level qudit. Using the off-resonant couplings between the resonators and the qudit, qudit-level-dependent frequency shifts on the two resonators are induced. The frequency shifts allow us to drive different resonators to the N-photon state when the qudit is in different intermediate levels. Consequently, the generation of NOON states with arbitrary photon number N can be completed in only three steps, i.e., driving the qudit to a superposition state of the two intermediate levels, driving one of the resonators to its N-photon state, and driving the qudit back to its ground level. Numerical simulations show that, in the regime of strong Kerr nonlinearity and coupling strengths, the protocol can produce the NOON state with high fidelity in the cases of different photon numbers. In addition, it is possible for the protocol to produce acceptable fidelity in the presence of systematic errors and decoherence factors. Therefore, the protocol may provide some useful perspectives for effective generation of photonic NOON states.
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9
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Wudarski F, Zhang Y, Dykman MI. Nonergodic Measurements of Qubit Frequency Noise. PHYSICAL REVIEW LETTERS 2023; 131:230201. [PMID: 38134761 DOI: 10.1103/physrevlett.131.230201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 09/26/2023] [Accepted: 11/13/2023] [Indexed: 12/24/2023]
Abstract
Slow fluctuations of a qubit frequency are one of the major problems faced by quantum computers. To understand their origin it is necessary to go beyond the analysis of their spectra. We show that characteristic features of the fluctuations can be revealed using comparatively short sequences of periodically repeated Ramsey measurements, with the sequence duration smaller than needed for the noise to approach the ergodic limit. The outcomes distribution and its dependence on the sequence duration are sensitive to the nature of the noise. The time needed for quantum measurements to display quasiergodic behavior can strongly depend on the measurement parameters.
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Affiliation(s)
- Filip Wudarski
- USRA Research Institute for Advanced Computer Science (RIACS), Mountain View, California 94043, USA
| | - Yaxing Zhang
- Google Quantum AI, Santa Barbara, California 93111, USA
| | - M I Dykman
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
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10
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Choi JR. Dynamics of Dispersive Measurements of Flux-Qubit States: Energy-Level Splitting Connected to Quantum Wave Mechanics. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2395. [PMID: 37686903 PMCID: PMC10490274 DOI: 10.3390/nano13172395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/09/2023] [Accepted: 08/16/2023] [Indexed: 09/10/2023]
Abstract
Superconducting flux qubits have many advantages as a storage of quantum information, such as broad range tunability of frequency, small-size fabricability, and high controllability. In the flux qubit-oscillator, qubits are connected to SQUID resonators for the purpose of performing dispersive non-destructive readouts of qubit signals with high fidelity. In this work, we propose a theoretical model for analyzing quantum characteristics of a flux qubit-oscillator on the basis of quantum solutions obtained using a unitary transformation approach. The energy levels of the combined system (qubit + resonator) are analyzed in detail. Equally spaced each energy level of the resonator splits into two parts depending on qubit states. Besides, coupling of the qubit to the resonator brings about an additional modification in the split energy levels. So long as the coupling strength and the tunnel splitting are not zero but finite values, the energy-level splitting of the resonator does not disappear. We conclude that quantum nondemolition dispersive measurements of the qubit states are possible by inducing bifurcation of the resonator states through the coupling.
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Affiliation(s)
- Jeong Ryeol Choi
- School of Electronic Engineering, Kyonggi University, Yeongtong-gu, Suwon 16227, Gyeonggi-do, Republic of Korea
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11
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Liu FM, Wang C, Chen MC, Chen H, Li SW, Shang ZX, Ying C, Wang JW, Huo YH, Peng CZ, Zhu X, Lu CY, Pan JW. Quantum computer-aided design for advanced superconducting qubit: Plasmonium. Sci Bull (Beijing) 2023; 68:1625-1631. [PMID: 37453825 DOI: 10.1016/j.scib.2023.06.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/14/2023] [Accepted: 06/25/2023] [Indexed: 07/18/2023]
Abstract
Complex quantum electronic circuits can be used to design noise-protected qubits, but their complexity may exceed the capabilities of classical simulation. In such cases, quantum computers are necessary for efficient simulation. In this work, we demonstrate the use of variational quantum computing on a transmon-based quantum processor to simulate a superconducting quantum electronic circuit and design a new type of qubit called "Plasmonium", which operates in the plasmon-transition regime. The fabricated Plasmonium qubits show a high two-qubit gate fidelity of 99.58(3)%, as well as a smaller physical size and larger anharmonicity compared to transmon qubits. These properties make Plasmonium a promising candidate for scaling up multi-qubit devices. Our results demonstrate the potential of using quantum computers to aid in the design of advanced quantum processors.
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Affiliation(s)
- Feng-Ming Liu
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Can Wang
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Ming-Cheng Chen
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.
| | - He Chen
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Shao-Wei Li
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Zhong-Xia Shang
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Chong Ying
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Jian-Wen Wang
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Yong-Heng Huo
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Cheng-Zhi Peng
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Xiaobo Zhu
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Chao-Yang Lu
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.
| | - Jian-Wei Pan
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China; Shanghai Branch CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
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12
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Wang SP, Ridolfo A, Li T, Savasta S, Nori F, Nakamura Y, You JQ. Probing the symmetry breaking of a light-matter system by an ancillary qubit. Nat Commun 2023; 14:4397. [PMID: 37474535 PMCID: PMC10359332 DOI: 10.1038/s41467-023-40097-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 07/11/2023] [Indexed: 07/22/2023] Open
Abstract
Hybrid quantum systems in the ultrastrong, and even more in the deep-strong, coupling regimes can exhibit exotic physical phenomena and promise new applications in quantum technologies. In these nonperturbative regimes, a qubit-resonator system has an entangled quantum vacuum with a nonzero average photon number in the resonator, where the photons are virtual and cannot be directly detected. The vacuum field, however, is able to induce the symmetry breaking of a dispersively coupled probe qubit. We experimentally observe the parity symmetry breaking of an ancillary Xmon artificial atom induced by the field of a lumped-element superconducting resonator deep-strongly coupled with a flux qubit. This result opens a way to experimentally explore the novel quantum-vacuum effects emerging in the deep-strong coupling regime.
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Affiliation(s)
- Shuai-Peng Wang
- Quantum Physics and Quantum Information Division, Beijing Computational Science Research Center, Beijing, 100193, China
- Interdisciplinary Center of Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou, 310027, China
| | - Alessandro Ridolfo
- Dipartimento di Fisica e Astronomia, Università di Catania, 95123, Catania, Italy
| | - Tiefu Li
- School of Integrated Circuits, and Frontier Science Center for Quantum Information, Tsinghua University, Beijing, 100084, China.
- Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
| | - Salvatore Savasta
- Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, Università di Messina, I-98166, Messina, Italy.
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako, Saitama, 351-0198, Japan
- Physics Department, The University of Michigan, Ann Arbor, MI, 48109-1040, USA
- RIKEN Center for Quantum Computing (RQC), Wako, Saitama, 351-0198, Japan
| | - Y Nakamura
- RIKEN Center for Quantum Computing (RQC), Wako, Saitama, 351-0198, Japan
- Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - J Q You
- Interdisciplinary Center of Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou, 310027, China.
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13
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Hassani F, Peruzzo M, Kapoor LN, Trioni A, Zemlicka M, Fink JM. Inductively shunted transmons exhibit noise insensitive plasmon states and a fluxon decay exceeding 3 hours. Nat Commun 2023; 14:3968. [PMID: 37407570 DOI: 10.1038/s41467-023-39656-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 06/22/2023] [Indexed: 07/07/2023] Open
Abstract
Currently available quantum processors are dominated by noise, which severely limits their applicability and motivates the search for new physical qubit encodings. In this work, we introduce the inductively shunted transmon, a weakly flux-tunable superconducting qubit that offers charge offset protection for all levels and a 20-fold reduction in flux dispersion compared to the state-of-the-art resulting in a constant coherence over a full flux quantum. The parabolic confinement provided by the inductive shunt as well as the linearity of the geometric superinductor facilitates a high-power readout that resolves quantum jumps with a fidelity and QND-ness of >90% and without the need for a Josephson parametric amplifier. Moreover, the device reveals quantum tunneling physics between the two prepared fluxon ground states with a measured average decay time of up to 3.5 h. In the future, fast time-domain control of the transition matrix elements could offer a new path forward to also achieve full qubit control in the decay-protected fluxon basis.
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Affiliation(s)
- F Hassani
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria.
| | - M Peruzzo
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - L N Kapoor
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - A Trioni
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - M Zemlicka
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - J M Fink
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria.
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14
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Somoroff A, Ficheux Q, Mencia RA, Xiong H, Kuzmin R, Manucharyan VE. Millisecond Coherence in a Superconducting Qubit. PHYSICAL REVIEW LETTERS 2023; 130:267001. [PMID: 37450803 DOI: 10.1103/physrevlett.130.267001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 03/24/2023] [Accepted: 05/10/2023] [Indexed: 07/18/2023]
Abstract
Improving control over physical qubits is a crucial component of quantum computing research. Here we report a superconducting fluxonium qubit with uncorrected coherence time T_{2}^{*}=1.48±0.13 ms, exceeding the state of the art for transmons by an order of magnitude. The average gate fidelity was benchmarked at 0.99991(1). Notably, even in the millisecond range, the coherence time is limited by material absorption and could be further improved with a more rigorous fabrication. Our demonstration may be useful for suppressing errors in the next generation quantum processors.
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Affiliation(s)
- Aaron Somoroff
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, USA
| | - Quentin Ficheux
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, USA
| | - Raymond A Mencia
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, USA
| | - Haonan Xiong
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, USA
| | - Roman Kuzmin
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, USA
| | - Vladimir E Manucharyan
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, USA
- École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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15
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Rower DA, Ateshian L, Li LH, Hays M, Bluvstein D, Ding L, Kannan B, Almanakly A, Braumüller J, Kim DK, Melville A, Niedzielski BM, Schwartz ME, Yoder JL, Orlando TP, Wang JIJ, Gustavsson S, Grover JA, Serniak K, Comin R, Oliver WD. Evolution of 1/f Flux Noise in Superconducting Qubits with Weak Magnetic Fields. PHYSICAL REVIEW LETTERS 2023; 130:220602. [PMID: 37327421 DOI: 10.1103/physrevlett.130.220602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 04/12/2023] [Indexed: 06/18/2023]
Abstract
The microscopic description of 1/f magnetic flux noise in superconducting circuits has remained an open question for several decades despite extensive experimental and theoretical investigation. Recent progress in superconducting devices for quantum information has highlighted the need to mitigate sources of qubit decoherence, driving a renewed interest in understanding the underlying noise mechanism(s). Though a consensus has emerged attributing flux noise to surface spins, their identity and interaction mechanisms remain unclear, prompting further study. Here, we apply weak in-plane magnetic fields to a capacitively shunted flux qubit (where the Zeeman splitting of surface spins lies below the device temperature) and study the flux-noise-limited qubit dephasing, revealing previously unexplored trends that may shed light on the dynamics behind the emergent 1/f noise. Notably, we observe an enhancement (suppression) of the spin-echo (Ramsey) pure-dephasing time in fields up to B=100 G. With direct noise spectroscopy, we further observe a transition from a 1/f to approximately Lorentzian frequency dependence below 10 Hz and a reduction of the noise above 1 MHz with increasing magnetic field. We suggest that these trends are qualitatively consistent with an increase of spin cluster sizes with magnetic field. These results should help to inform a complete microscopic theory of 1/f flux noise in superconducting circuits.
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Affiliation(s)
- David A Rower
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Lamia Ateshian
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Lauren H Li
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Max Hays
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Dolev Bluvstein
- Department of Physics, Harvard University, Cambridge, Massachusetts 02139, USA
| | - Leon Ding
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Bharath Kannan
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Aziza Almanakly
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jochen Braumüller
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - David K Kim
- MIT Lincoln Laboratory, Lexington, Massachusetts 02421, USA
| | | | | | | | | | - Terry P Orlando
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Joel I-Jan Wang
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jeffrey A Grover
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Kyle Serniak
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- MIT Lincoln Laboratory, Lexington, Massachusetts 02421, USA
| | - Riccardo Comin
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - William D Oliver
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- MIT Lincoln Laboratory, Lexington, Massachusetts 02421, USA
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16
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Liu YQ, Yang YJ, Yu CS. Quantum heat diode versus light emission in circuit quantum electrodynamical system. Phys Rev E 2023; 107:044121. [PMID: 37198796 DOI: 10.1103/physreve.107.044121] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Accepted: 04/03/2023] [Indexed: 05/19/2023]
Abstract
Precisely controlling heat transfer in a quantum mechanical system is particularly significant for designing quantum thermodynamical devices. With the technology of experiment advances, circuit quantum electrodynamics (circuit QED) has become a promising system due to controllable light-matter interactions as well as flexible coupling strengths. In this paper, we design a thermal diode in terms of the two-photon Rabi model of the circuit QED system. We find that the thermal diode can not only be realized in the resonant coupling but also achieve better performance, especially for the detuned qubit-photon ultrastrong coupling. We also study the photonic detection rates and their nonreciprocity, which indicate similar behaviors with the nonreciprocal heat transport. This provides the potential to understand thermal diode behavior from the quantum optical perspective and could shed new insight into the relevant research on thermodynamical devices.
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Affiliation(s)
- Yu-Qiang Liu
- School of Physics, Dalian University of Technology, Dalian 116024, China
| | - Yi-Jia Yang
- School of Physics, Dalian University of Technology, Dalian 116024, China
| | - Chang-Shui Yu
- School of Physics, Dalian University of Technology, Dalian 116024, China
- DUT-BSU Joint Institute, Dalian University of Technology, Dalian 116024, China
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17
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Yang H, Kim NY. Material-Inherent Noise Sources in Quantum Information Architecture. MATERIALS (BASEL, SWITZERLAND) 2023; 16:2561. [PMID: 37048853 PMCID: PMC10094895 DOI: 10.3390/ma16072561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 10/17/2022] [Accepted: 11/22/2022] [Indexed: 06/19/2023]
Abstract
NISQ is a representative keyword at present as an acronym for "noisy intermediate-scale quantum", which identifies the current era of quantum information processing (QIP) technologies. QIP science and technologies aim to accomplish unprecedented performance in computation, communications, simulations, and sensing by exploiting the infinite capacity of parallelism, coherence, and entanglement as governing quantum mechanical principles. For the last several decades, quantum computing has reached to the technology readiness level 5, where components are integrated to build mid-sized commercial products. While this is a celebrated and triumphant achievement, we are still a great distance away from quantum-superior, fault-tolerant architecture. To reach this goal, we need to harness technologies that recognize undesirable factors to lower fidelity and induce errors from various sources of noise with controllable correction capabilities. This review surveys noisy processes arising from materials upon which several quantum architectures have been constructed, and it summarizes leading research activities in searching for origins of noise and noise reduction methods to build advanced, large-scale quantum technologies in the near future.
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Affiliation(s)
- HeeBong Yang
- Institute of Quantum Computing, University of Waterloo, 200 University Ave. West, Waterloo, ON N2L 3G1, Canada
- Department of Electrical and Computer Engineering, Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. West, Waterloo, ON N2L 3G1, Canada
- Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. West, Waterloo, ON N2L 3G1, Canada
| | - Na Young Kim
- Institute of Quantum Computing, University of Waterloo, 200 University Ave. West, Waterloo, ON N2L 3G1, Canada
- Department of Electrical and Computer Engineering, Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. West, Waterloo, ON N2L 3G1, Canada
- Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave. West, Waterloo, ON N2L 3G1, Canada
- Department of Physics and Astronomy, University of Waterloo, 200 University Ave. West, Waterloo, ON N2L 3G1, Canada
- Department of Chemistry, University of Waterloo, 200 University Ave. West, Waterloo, ON N2L 3G1, Canada
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18
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Mozgunov E, Lidar DA. Quantum adiabatic theorem for unbounded Hamiltonians with a cutoff and its application to superconducting circuits. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20210407. [PMID: 36463925 PMCID: PMC9719797 DOI: 10.1098/rsta.2021.0407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 07/18/2022] [Indexed: 06/17/2023]
Abstract
We present a new quantum adiabatic theorem that allows one to rigorously bound the adiabatic timescale for a variety of systems, including those described by originally unbounded Hamiltonians that are made finite-dimensional by a cutoff. Our bound is geared towards the qubit approximation of superconducting circuits and presents a sufficient condition for remaining within the [Formula: see text]-dimensional qubit subspace of a circuit model of [Formula: see text] qubits. The novelty of this adiabatic theorem is that, unlike previous rigorous results, it does not contain [Formula: see text] as a factor in the adiabatic timescale, and it allows one to obtain an expression for the adiabatic timescale independent of the cutoff of the infinite-dimensional Hilbert space of the circuit Hamiltonian. As an application, we present an explicit dependence of this timescale on circuit parameters for a superconducting flux qubit and demonstrate that leakage out of the qubit subspace is inevitable as the tunnelling barrier is raised towards the end of a quantum anneal. We also discuss a method of obtaining a [Formula: see text] effective Hamiltonian that best approximates the true dynamics induced by slowly changing circuit control parameters. This article is part of the theme issue 'Quantum annealing and computation: challenges and perspectives'.
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Affiliation(s)
- Evgeny Mozgunov
- Center for Quantum Information Science and Technology, University of Southern California, Los Angeles, CA 90089, USA
| | - Daniel A. Lidar
- Center for Quantum Information Science and Technology, University of Southern California, Los Angeles, CA 90089, USA
- Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA 90089, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
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19
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Yamamoto K, Endo S, Hakoshima H, Matsuzaki Y, Tokunaga Y. Error-Mitigated Quantum Metrology via Virtual Purification. PHYSICAL REVIEW LETTERS 2022; 129:250503. [PMID: 36608222 DOI: 10.1103/physrevlett.129.250503] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 07/13/2022] [Accepted: 08/11/2022] [Indexed: 06/17/2023]
Abstract
Quantum metrology with entangled resources aims to achieve sensitivity beyond the standard quantum limit by harnessing quantum effects even in the presence of environmental noise. So far, sensitivity has been mainly discussed from the viewpoint of reducing statistical errors under the assumption of perfect knowledge of a noise model. However, we cannot always obtain complete information about a noise model due to coherence time fluctuations, which are frequently observed in experiments. Such unknown fluctuating noise leads to systematic errors and nullifies the quantum advantages. Here, we propose an error-mitigated quantum metrology that can filter out unknown fluctuating noise with the aid of purification-based quantum error mitigation. We demonstrate that our protocol mitigates systematic errors and recovers superclassical scaling in a practical situation with time-inhomogeneous bias-inducing noise. Our result is the first demonstration to reveal the usefulness of purification-based error mitigation for unknown fluctuating noise, thus paving the way not only for practical quantum metrology but also for quantum computation affected by such noise.
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Affiliation(s)
- Kaoru Yamamoto
- NTT Computer and Data Science Laboratories, NTT Corporation, Musashino 180-8585, Japan
| | - Suguru Endo
- NTT Computer and Data Science Laboratories, NTT Corporation, Musashino 180-8585, Japan
- JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Hideaki Hakoshima
- Research Center for Emerging Computing Technologies, National Institute of Advanced Industrial Science and Technology (AIST), Central2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
- Center for Quantum Information and Quantum Biology, Osaka University, 1-2 Machikaneyama, Toyonaka 560-0043, Japan
| | - Yuichiro Matsuzaki
- Research Center for Emerging Computing Technologies, National Institute of Advanced Industrial Science and Technology (AIST), Central2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
- NEC-AIST Quantum Technology Cooperative Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
| | - Yuuki Tokunaga
- NTT Computer and Data Science Laboratories, NTT Corporation, Musashino 180-8585, Japan
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20
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Menke T, Banner WP, Bergamaschi TR, Di Paolo A, Vepsäläinen A, Weber SJ, Winik R, Melville A, Niedzielski BM, Rosenberg D, Serniak K, Schwartz ME, Yoder JL, Aspuru-Guzik A, Gustavsson S, Grover JA, Hirjibehedin CF, Kerman AJ, Oliver WD. Demonstration of Tunable Three-Body Interactions between Superconducting Qubits. PHYSICAL REVIEW LETTERS 2022; 129:220501. [PMID: 36493437 DOI: 10.1103/physrevlett.129.220501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 10/17/2022] [Indexed: 06/17/2023]
Abstract
Nonpairwise multiqubit interactions present a useful resource for quantum information processors. Their implementation would facilitate more efficient quantum simulations of molecules and combinatorial optimization problems, and they could simplify error suppression and error correction schemes. Here, we present a superconducting circuit architecture in which a coupling module mediates two-local and three-local interactions between three flux qubits by design. The system Hamiltonian is estimated via multiqubit pulse sequences that implement Ramsey-type interferometry between all neighboring excitation manifolds in the system. The three-local interaction is coherently tunable over several MHz via the coupler flux biases and can be turned off, which is important for applications in quantum annealing, analog quantum simulation, and gate-model quantum computation.
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Affiliation(s)
- Tim Menke
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - William P Banner
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Thomas R Bergamaschi
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Agustin Di Paolo
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Antti Vepsäläinen
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Steven J Weber
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426, USA
| | - Roni Winik
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Alexander Melville
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426, USA
| | - Bethany M Niedzielski
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426, USA
| | - Danna Rosenberg
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426, USA
| | - Kyle Serniak
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426, USA
| | - Mollie E Schwartz
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426, USA
| | - Jonilyn L Yoder
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426, USA
| | - Alán Aspuru-Guzik
- Departments of Chemistry and Computer Science, University of Toronto, Toronto, Ontario M5G 1Z8, Canada
- Vector Institute for Artificial Intelligence, Toronto, Ontario M5S 1M1, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jeffrey A Grover
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Cyrus F Hirjibehedin
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426, USA
| | - Andrew J Kerman
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426, USA
| | - William D Oliver
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02421-6426, USA
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21
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Schegolev AE, Klenov NV, Bogatskaya AV, Yusupov RD, Popov AM. A Pair of Coupled Waveguides as a Classical Analogue for a Solid-State Qubit. SENSORS (BASEL, SWITZERLAND) 2022; 22:8286. [PMID: 36365983 PMCID: PMC9655956 DOI: 10.3390/s22218286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/25/2022] [Accepted: 10/27/2022] [Indexed: 06/16/2023]
Abstract
We have determined conditions when a pair of coupled waveguides, a common element for integrated room-temperature photonics, can act as a qubit based on a system with a double-well potential. Moreover, we have used slow-varying amplitude approximation (SVA) for the "classical" wave equation to study the propagation of electromagnetic beams in a couple of dielectric waveguides both analytically and numerically. As a part of an extension of the optical-mechanical analogy, we have considered examples of "quantum operations" on the electromagnetic wave state in a pair of waveguides. Furthermore, we have provided examples of "quantum-mechanical" calculations of nonlinear transfer functions for the implementation of the considered element in optical neural networks.
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Affiliation(s)
- Andrey E Schegolev
- D. V. Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119991 Moscow, Russia
- Science and Research Department, Moscow Technical University of Communication and Informatics, 111024 Moscow, Russia
| | - Nikolay V Klenov
- Faculty of Physics, Moscow State University, 119991 Moscow, Russia
| | - Anna V Bogatskaya
- Faculty of Physics, Moscow State University, 119991 Moscow, Russia
- P. N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Rustam D Yusupov
- Science and Research Department, Moscow Technical University of Communication and Informatics, 111024 Moscow, Russia
- Faculty of Physics, Moscow State University, 119991 Moscow, Russia
| | - Alexander M Popov
- Faculty of Physics, Moscow State University, 119991 Moscow, Russia
- P. N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
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22
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Pereira L, García-Ripoll JJ, Ramos T. Complete Physical Characterization of Quantum Nondemolition Measurements via Tomography. PHYSICAL REVIEW LETTERS 2022; 129:010402. [PMID: 35841584 DOI: 10.1103/physrevlett.129.010402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 06/03/2022] [Indexed: 06/15/2023]
Abstract
We introduce a self-consistent tomography for arbitrary quantum nondemolition (QND) detectors. Based on this, we build a complete physical characterization of the detector, including the measurement processes and a quantification of the fidelity, ideality, and backaction of the measurement. This framework is a diagnostic tool for the dynamics of QND detectors, allowing us to identify errors, and to improve their calibration and design. We illustrate this on a realistic Jaynes-Cummings simulation of a superconducting qubit readout. We characterize nondispersive errors, quantify the backaction introduced by the readout cavity, and calibrate the optimal measurement point.
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Affiliation(s)
- L Pereira
- Instituto de Física Fundamental IFF-CSIC, Calle Serrano 113b, Madrid 28006, Spain
| | - J J García-Ripoll
- Instituto de Física Fundamental IFF-CSIC, Calle Serrano 113b, Madrid 28006, Spain
| | - T Ramos
- Instituto de Física Fundamental IFF-CSIC, Calle Serrano 113b, Madrid 28006, Spain
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23
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Kamimura S, Hakoshima H, Matsuzaki Y, Yoshida K, Tokura Y. Quantum-Enhanced Heat Engine Based on Superabsorption. PHYSICAL REVIEW LETTERS 2022; 128:180602. [PMID: 35594102 DOI: 10.1103/physrevlett.128.180602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 12/21/2021] [Accepted: 03/21/2022] [Indexed: 06/15/2023]
Abstract
We propose a quantum-enhanced heat engine with entanglement. The key feature of our scheme is superabsorption, which facilitates enhanced energy absorption by entangled qubits. Whereas a conventional engine with N separable qubits provides power with a scaling of P=Θ(N), our engine uses superabsorption to provide power with a quantum scaling of P=Θ(N^{2}). This quantum heat engine also exhibits a scaling advantage over classical ones composed of N-particle Langevin systems. Our work elucidates the quantum properties allowing for the enhancement of performance.
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Affiliation(s)
- Shunsuke Kamimura
- Research Center for Emerging Computing Technologies, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan
| | - Hideaki Hakoshima
- Research Center for Emerging Computing Technologies, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
- Center for Quantum Information and Quantum Biology, Osaka University, 1-2 Machikaneyama, Toyonaka 560-0043, Japan
| | - Yuichiro Matsuzaki
- Research Center for Emerging Computing Technologies, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Kyo Yoshida
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan
| | - Yasuhiro Tokura
- Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan
- Tsukuba Research Center for Energy Materials Science (TREMS), Tsukuba 305-8571, Japan
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24
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Weak spin-flip scattering in Pd 89Ni 11 interlayer of NbN-based ferromagnetic Josephson junctions. Sci Rep 2022; 12:6863. [PMID: 35478215 PMCID: PMC9046396 DOI: 10.1038/s41598-022-10967-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 04/13/2022] [Indexed: 11/16/2022] Open
Abstract
We studied niobium nitride (NbN)-based π-junctions with a diluted ferromagnetic Pd89Ni11 interlayer (NbN/PdNi/NbN junctions). In the NbN/PdNi/NbN junctions with various PdNi thicknesses, we observed a non-monotonic dependence of the critical currents on PdNi thickness, indicating the effects of the exchange interaction on the superconducting order parameter. From theoretical fitting of the experimental data, we found that the NbN/PdNi/NbN junctions showed a significantly smaller degree of spin-flip scattering in the PdNi interlayer than in the CuNi interlayer of NbN/CuNi/NbN junctions reported previously. The weak spin-flip scattering leads to a longer decay length of the Josephson critical current, so the critical currents were observed over a wide range of PdNi thicknesses (10–40 nm). We also fabricated superconducting quantum interference devices (SQUIDs) including the NbN/PdNi/NbN junction, using a PdNi thickness in which the π-state was expected. A half-flux-quantum shift, as evidence of the π-state, was observed in the magnetic field-dependent critical currents of the SQUIDs. This result represents an important step towards the practical application of NbN-based π-Josephson junctions.
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25
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Wang JIJ, Yamoah MA, Li Q, Karamlou AH, Dinh T, Kannan B, Braumüller J, Kim D, Melville AJ, Muschinske SE, Niedzielski BM, Serniak K, Sung Y, Winik R, Yoder JL, Schwartz ME, Watanabe K, Taniguchi T, Orlando TP, Gustavsson S, Jarillo-Herrero P, Oliver WD. Hexagonal boron nitride as a low-loss dielectric for superconducting quantum circuits and qubits. NATURE MATERIALS 2022; 21:398-403. [PMID: 35087240 DOI: 10.1038/s41563-021-01187-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 12/08/2021] [Indexed: 06/14/2023]
Abstract
Dielectrics with low loss at microwave frequencies are imperative for high-coherence solid-state quantum computing platforms. Here we study the dielectric loss of hexagonal boron nitride (hBN) thin films in the microwave regime by measuring the quality factor of parallel-plate capacitors (PPCs) made of NbSe2-hBN-NbSe2 heterostructures integrated into superconducting circuits. The extracted microwave loss tangent of hBN is bounded to be at most in the mid-10-6 range in the low-temperature, single-photon regime. We integrate hBN PPCs with aluminium Josephson junctions to realize transmon qubits with coherence times reaching 25 μs, consistent with the hBN loss tangent inferred from resonator measurements. The hBN PPC reduces the qubit feature size by approximately two orders of magnitude compared with conventional all-aluminium coplanar transmons. Our results establish hBN as a promising dielectric for building high-coherence quantum circuits with substantially reduced footprint and with a high energy participation that helps to reduce unwanted qubit cross-talk.
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Affiliation(s)
- Joel I-J Wang
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Megan A Yamoah
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Qing Li
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Amir H Karamlou
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Thao Dinh
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bharath Kannan
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jochen Braumüller
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - David Kim
- MIT Lincoln Laboratory, Lexington, MA, USA
| | | | - Sarah E Muschinske
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | | - Youngkyu Sung
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Roni Winik
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Terry P Orlando
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - William D Oliver
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
- MIT Lincoln Laboratory, Lexington, MA, USA.
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26
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Intrinsic and induced quantum quenches for enhancing qubit-based quantum noise spectroscopy. Nat Commun 2021; 12:6528. [PMID: 34764276 PMCID: PMC8586144 DOI: 10.1038/s41467-021-26868-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 10/26/2021] [Indexed: 11/18/2022] Open
Abstract
Quantum sensing protocols that exploit the dephasing of a probe qubit are powerful and ubiquitous methods for interrogating an unknown environment. They have a variety of applications, ranging from noise mitigation in quantum processors, to the study of correlated electron states. Here, we discuss a simple strategy for enhancing these methods, based on the fact that they often give rise to an inadvertent quench of the probed system: there is an effective sudden change in the environmental Hamiltonian at the start of the sensing protocol. These quenches are extremely sensitive to the initial environmental state, and lead to observable changes in the sensor qubit evolution. We show how these new features give access to environmental response properties. This enables methods for direct measurement of bath temperature, and for detecting non-thermal equilibrium states. We also discuss how to deliberately control and modulate this quench physics, which enables reconstruction of the bath spectral function. Extensions to non-Gaussian quantum baths are also discussed, as is the application of our ideas to a range of sensing platforms (e.g., nitrogen-vacancy (NV) centers in diamond, semiconductor quantum dots, and superconducting circuits).
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27
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Niepce D, Burnett JJ, Kudra M, Cole JH, Bylander J. Stability of superconducting resonators: Motional narrowing and the role of Landau-Zener driving of two-level defects. SCIENCE ADVANCES 2021; 7:eabh0462. [PMID: 34559556 PMCID: PMC8462906 DOI: 10.1126/sciadv.abh0462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Frequency instability of superconducting resonators and qubits leads to dephasing and time-varying energy loss and hinders quantum processor tune-up. Its main source is dielectric noise originating in surface oxides. Thorough noise studies are needed to develop a comprehensive understanding and mitigation strategy of these fluctuations. We use a frequency-locked loop to track the resonant frequency jitter of three different resonator types—one niobium nitride superinductor, one aluminum coplanar waveguide, and one aluminum cavity—and we observe notably similar random telegraph signal fluctuations. At low microwave drive power, the resonators exhibit multiple, unstable frequency positions, which, for increasing power, coalesce into one frequency due to motional narrowing caused by sympathetic driving of two-level system defects by the resonator. In all three devices, we identify a dominant fluctuator whose switching amplitude (separation between states) saturates with increasing drive power, but whose characteristic switching rate follows the power law dependence of quasi-classical Landau-Zener transitions.
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Affiliation(s)
- David Niepce
- Chalmers University of Technology, Microtechnology, and Nanoscience, SE-41296 Gothenburg, Sweden
| | - Jonathan J. Burnett
- National Physical Laboratory, Hampton Road, Teddington Middlesex TW11 0LW, UK
| | - Marina Kudra
- Chalmers University of Technology, Microtechnology, and Nanoscience, SE-41296 Gothenburg, Sweden
| | - Jared H. Cole
- Chemical and Quantum Physics, School of Science, RMIT University, Melbourne, VIC 3001, Australia
| | - Jonas Bylander
- Chalmers University of Technology, Microtechnology, and Nanoscience, SE-41296 Gothenburg, Sweden
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28
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Farrar LS, Nevill A, Lim ZJ, Balakrishnan G, Dale S, Bending SJ. Superconducting Quantum Interference in Twisted van der Waals Heterostructures. NANO LETTERS 2021; 21:6725-6731. [PMID: 34428907 PMCID: PMC8397396 DOI: 10.1021/acs.nanolett.1c00152] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 07/21/2021] [Indexed: 06/13/2023]
Abstract
We demonstrate the formation of both Josephson junctions and superconducting quantum interference devices (SQUIDs) using a dry transfer technique to stack and deterministically misalign mechanically exfoliated flakes of NbSe2. The current-voltage characteristics of the resulting twisted NbSe2-NbSe2 junctions are found to be sensitive to the misalignment angle of the crystallographic axes, opening up a new control parameter for optimization of the device performance, which is not available in thin-film-deposited junctions. A single lithographic process has then been implemented to shape Josephson junctions into SQUID geometries with typical loop areas of ∼25 μm2 and weak links ∼600 nm wide. At T = 3.75 K in an applied magnetic field, these devices display large stable current and voltage modulation depths of up to ΔIc ∼ 75% and ΔV ∼ 1.4 mV, respectively.
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Affiliation(s)
- Liam S. Farrar
- Department
of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Aimee Nevill
- Department
of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Zhen Jieh Lim
- Department
of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Geetha Balakrishnan
- Department
of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Sara Dale
- Department
of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - Simon J. Bending
- Department
of Physics, University of Bath, Bath BA2 7AY, United Kingdom
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29
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Chirolli L, Moore JE. Enhanced Coherence in Superconducting Circuits via Band Engineering. PHYSICAL REVIEW LETTERS 2021; 126:187701. [PMID: 34018786 DOI: 10.1103/physrevlett.126.187701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 04/06/2021] [Indexed: 06/12/2023]
Abstract
In superconducting circuits interrupted by Josephson junctions, the dependence of the energy spectrum on offset charges on different islands is 2e periodic through the Aharonov-Casher effect and resembles a crystal band structure that reflects the symmetries of the Josephson potential. We show that higher-harmonic Josephson elements described by a cos(2φ) energy-phase relation provide an increased freedom to tailor the shape of the Josephson potential and design spectra featuring multiplets of flat bands and Dirac points in the charge Brillouin zone. Flat bands provide noise-insensitive energy levels, and consequently, engineering band pairs with flat spectral gaps can help improve the coherence of the system. We discuss a modified version of a flux qubit that achieves, in principle, no decoherence from charge noise and introduce a flux qutrit that shows a spin-1 Dirac spectrum and is simultaneously quite robust to both charge and flux noise.
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Affiliation(s)
- Luca Chirolli
- Department of Physics, University of California, Berkeley, California 94720, USA
- Istituto Nanoscienze-CNR, I-56127 Pisa, Italy
| | - Joel E Moore
- Department of Physics, University of California, Berkeley, California 94720, USA
- Lawrence Berkeley National Laboratory, Materials Sciences Division, Berkeley, California 94720, USA
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30
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Wang Z, Xu M, Han X, Fu W, Puri S, Girvin SM, Tang HX, Shankar S, Devoret MH. Quantum Microwave Radiometry with a Superconducting Qubit. PHYSICAL REVIEW LETTERS 2021; 126:180501. [PMID: 34018799 DOI: 10.1103/physrevlett.126.180501] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 03/29/2021] [Indexed: 06/12/2023]
Abstract
The interaction of photons and coherent quantum systems can be employed to detect electromagnetic radiation with remarkable sensitivity. We introduce a quantum radiometer based on the photon-induced dephasing process of a superconducting qubit for sensing microwave radiation at the subunit photon level. Using this radiometer, we demonstrate the radiative cooling of a 1 K microwave resonator and measure its mode temperature with an uncertainty ∼0.01 K. We thus develop a precise tool for studying the thermodynamics of quantum microwave circuits, which provides new solutions for calibrating hybrid quantum systems and detecting candidate particles for dark matter.
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Affiliation(s)
- Zhixin Wang
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Mingrui Xu
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - Xu Han
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - Wei Fu
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - Shruti Puri
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - S M Girvin
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Hong X Tang
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520, USA
| | - S Shankar
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - M H Devoret
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
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31
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de Leon NP, Itoh KM, Kim D, Mehta KK, Northup TE, Paik H, Palmer BS, Samarth N, Sangtawesin S, Steuerman DW. Materials challenges and opportunities for quantum computing hardware. Science 2021; 372:372/6539/eabb2823. [PMID: 33859004 DOI: 10.1126/science.abb2823] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Quantum computing hardware technologies have advanced during the past two decades, with the goal of building systems that can solve problems that are intractable on classical computers. The ability to realize large-scale systems depends on major advances in materials science, materials engineering, and new fabrication techniques. We identify key materials challenges that currently limit progress in five quantum computing hardware platforms, propose how to tackle these problems, and discuss some new areas for exploration. Addressing these materials challenges will require scientists and engineers to work together to create new, interdisciplinary approaches beyond the current boundaries of the quantum computing field.
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Affiliation(s)
- Nathalie P de Leon
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Kohei M Itoh
- School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan
| | - Dohun Kim
- Department of Physics and Astronomy and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
| | - Karan K Mehta
- Department of Physics, Institute for Quantum Electronics, ETH Zürich, 8092 Zürich, Switzerland
| | - Tracy E Northup
- Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria
| | - Hanhee Paik
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, NY 10598, USA.
| | - B S Palmer
- Laboratory for Physical Sciences, University of Maryland, College Park, MD 20740, USA.,Quantum Materials Center, University of Maryland, College Park, MD 20742, USA
| | - N Samarth
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Sorawis Sangtawesin
- School of Physics and Center of Excellence in Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - D W Steuerman
- Kavli Foundation, 5715 Mesmer Avenue, Los Angeles, CA 90230, USA
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32
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Rosenthal EI, Schneider CMF, Malnou M, Zhao Z, Leditzky F, Chapman BJ, Wustmann W, Ma X, Palken DA, Zanner MF, Vale LR, Hilton GC, Gao J, Smith G, Kirchmair G, Lehnert KW. Efficient and Low-Backaction Quantum Measurement Using a Chip-Scale Detector. PHYSICAL REVIEW LETTERS 2021; 126:090503. [PMID: 33750151 DOI: 10.1103/physrevlett.126.090503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 01/21/2021] [Indexed: 06/12/2023]
Abstract
Superconducting qubits are a leading platform for scalable quantum computing and quantum error correction. One feature of this platform is the ability to perform projective measurements orders of magnitude more quickly than qubit decoherence times. Such measurements are enabled by the use of quantum-limited parametric amplifiers in conjunction with ferrite circulators-magnetic devices which provide isolation from noise and decoherence due to amplifier backaction. Because these nonreciprocal elements have limited performance and are not easily integrated on chip, it has been a long-standing goal to replace them with a scalable alternative. Here, we demonstrate a solution to this problem by using a superconducting switch to control the coupling between a qubit and amplifier. Doing so, we measure a transmon qubit using a single, chip-scale device to provide both parametric amplification and isolation from the bulk of amplifier backaction. This measurement is also fast, high fidelity, and has 70% efficiency, comparable to the best that has been reported in any superconducting qubit measurement. As such, this work constitutes a high-quality platform for the scalable measurement of superconducting qubits.
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Affiliation(s)
- Eric I Rosenthal
- JILA, University of Colorado, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Christian M F Schneider
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Experimental Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Maxime Malnou
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Ziyi Zhao
- JILA, University of Colorado, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Felix Leditzky
- JILA, University of Colorado, Boulder, Colorado 80309, USA
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
- Department of Mathematics & Illinois Quantum Information Science and Technology Center, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| | - Benjamin J Chapman
- Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Waltraut Wustmann
- The Laboratory for Physical Sciences, College Park, Maryland 20740, USA
| | - Xizheng Ma
- JILA, University of Colorado, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Daniel A Palken
- JILA, University of Colorado, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Maximilian F Zanner
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Experimental Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Leila R Vale
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Gene C Hilton
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Jiansong Gao
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
| | - Graeme Smith
- JILA, University of Colorado, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| | - Gerhard Kirchmair
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Experimental Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - K W Lehnert
- JILA, University of Colorado, Boulder, Colorado 80309, USA
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- National Institute of Standards and Technology, Boulder, Colorado 80305, USA
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33
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Sung Y, Vepsäläinen A, Braumüller J, Yan F, Wang JIJ, Kjaergaard M, Winik R, Krantz P, Bengtsson A, Melville AJ, Niedzielski BM, Schwartz ME, Kim DK, Yoder JL, Orlando TP, Gustavsson S, Oliver WD. Multi-level quantum noise spectroscopy. Nat Commun 2021; 12:967. [PMID: 33574240 PMCID: PMC7878521 DOI: 10.1038/s41467-021-21098-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 01/13/2021] [Indexed: 11/08/2022] Open
Abstract
System noise identification is crucial to the engineering of robust quantum systems. Although existing quantum noise spectroscopy (QNS) protocols measure an aggregate amount of noise affecting a quantum system, they generally cannot distinguish between the underlying processes that contribute to it. Here, we propose and experimentally validate a spin-locking-based QNS protocol that exploits the multi-level energy structure of a superconducting qubit to achieve two notable advances. First, our protocol extends the spectral range of weakly anharmonic qubit spectrometers beyond the present limitations set by their lack of strong anharmonicity. Second, the additional information gained from probing the higher-excited levels enables us to identify and distinguish contributions from different underlying noise mechanisms.
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Affiliation(s)
- Youngkyu Sung
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Antti Vepsäläinen
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jochen Braumüller
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Fei Yan
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Joel I-Jan Wang
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Morten Kjaergaard
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Roni Winik
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Philip Krantz
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Andreas Bengtsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | | | | | | | | - Terry P Orlando
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - William D Oliver
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
- MIT Lincoln Laboratory, Lexington, MA, USA.
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
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34
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Szczęśniak D, Kais S. Magnetic flux noise in superconducting qubits and the gap states continuum. Sci Rep 2021; 11:1813. [PMID: 33469096 PMCID: PMC7815792 DOI: 10.1038/s41598-021-81450-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 12/29/2020] [Indexed: 01/29/2023] Open
Abstract
In the present study we investigate the selected local aspects of the metal-induced gap states (MIGSs) at the disordered metal-insulator interface, that were previously proposed to produce magnetic moments responsible for the magnetic flux noise in some of the superconducting qubit modalities. Our analysis attempts to supplement the available studies and provide new theoretical contribution toward their validation. In particular, we explicitly discuss the behavior of the MIGSs in the momentum space as a function of the onsite energy deviation, that mimics random potential disorder at the interface in the local approximation. It is found, that when the difference between the characteristic electronic potentials in the insulator increases, the corresponding MIGSs become more localized. This effect is associated with the increasing degree of the potential disorder that was earlier observed to produce highly localized MIGSs in the superconducting qubits. At the same time, the presented findings show that the disorder-induced localization of the MIGSs can be related directly to the decay characteristics of these states as well as to the bulk electronic properties of the insulator. As a result, our study reinforces plausibility of the previous corresponding investigations on the origin of the flux noise, but also allows to draw future directions toward their better verification.
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Affiliation(s)
- Dominik Szczęśniak
- Department of Chemistry, Purdue University, 560 Oval Dr., West Lafayette, IN, 47907, USA.
- Department of Theoretical Physics, Faculty of Science and Technology, Jan Długosz University in Częstochowa, 13/15 Armii Krajowej Ave., 42200, Czestochowa, Poland.
| | - Sabre Kais
- Department of Chemistry, Purdue University, 560 Oval Dr., West Lafayette, IN, 47907, USA
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35
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de Graaf SE, Faoro L, Ioffe LB, Mahashabde S, Burnett JJ, Lindström T, Kubatkin SE, Danilov AV, Tzalenchuk AY. Two-level systems in superconducting quantum devices due to trapped quasiparticles. SCIENCE ADVANCES 2020; 6:eabc5055. [PMID: 33355127 PMCID: PMC11206451 DOI: 10.1126/sciadv.abc5055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 10/30/2020] [Indexed: 06/12/2023]
Abstract
A major issue for the implementation of large-scale superconducting quantum circuits is the interaction with interfacial two-level system (TLS) defects that lead to qubit parameter fluctuations and relaxation. Another major challenge comes from nonequilibrium quasiparticles (QPs) that result in qubit relaxation and dephasing. Here, we reveal a previously unexplored decoherence mechanism in the form of a new type of TLS originating from trapped QPs, which can induce qubit relaxation. Using spectral, temporal, thermal, and magnetic field mapping of TLS-induced fluctuations in frequency tunable resonators, we identify a highly coherent subset of the general TLS population with a low reconfiguration temperature ∼300 mK and a nonuniform density of states. These properties can be understood if the TLS are formed by QPs trapped in shallow subgap states formed by spatial fluctutations of the superconducting order parameter. This implies that even very rare QP bursts will affect coherence over exponentially long time scales.
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Affiliation(s)
- S E de Graaf
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK.
| | - L Faoro
- Sorbonne Université, Laboratoire de Physique Théorique et Hautes Énergies, UMR 7589 CNRS, Tour 13, 5eme Etage, 4 Place Jussieu, F-75252 Paris 05, France
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - L B Ioffe
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
- Google Inc., Venice, CA 90291, USA
| | - S Mahashabde
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-41296 Goteborg, Sweden
| | - J J Burnett
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK
| | - T Lindström
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK
| | - S E Kubatkin
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-41296 Goteborg, Sweden
| | - A V Danilov
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-41296 Goteborg, Sweden
| | - A Ya Tzalenchuk
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK
- Royal Holloway, University of London, Egham TW20 0EX, UK
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36
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Zhang H, Su QP, Yang CP. Efficient scheme for creating a W-type optical entangled coherent state. OPTICS EXPRESS 2020; 28:35622-35635. [PMID: 33379674 DOI: 10.1364/oe.411810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 10/30/2020] [Indexed: 06/12/2023]
Abstract
W-type optical entangled coherent states have important applications in quantum communication. Previous works require performing measurement in the preparation of such W states. We here propose an efficient scheme for creating a W-type optical entangled coherent state without measurement. This scheme employs a setup composed of three microwave cavities and a superconducting flux coupler qutrit. Because no measurement is required, the W state can be generated deterministically. In addition, the system complexity is greatly reduced because of using only one qutrit to couple the three cavities. Numerical analysis shows that within current experimental technology, the W state can be prepared with high fidelity. This scheme is universal and can be extended to create the W-type optical entangled coherent state, by using three microwave or optical cavities coupled via a three-level natural or artificial atom.
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37
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Ku J, Xu X, Brink M, McKay DC, Hertzberg JB, Ansari MH, Plourde BLT. Suppression of Unwanted ZZ Interactions in a Hybrid Two-Qubit System. PHYSICAL REVIEW LETTERS 2020; 125:200504. [PMID: 33258640 DOI: 10.1103/physrevlett.125.200504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 09/02/2020] [Indexed: 06/12/2023]
Abstract
Mitigating crosstalk errors, whether classical or quantum mechanical, is critically important for achieving high-fidelity entangling gates in multiqubit circuits. For weakly anharmonic superconducting qubits, unwanted ZZ interactions can be suppressed by combining qubits with opposite anharmonicity. We present experimental measurements and theoretical modeling of two-qubit gate error for gates based on the cross resonance interaction between a capacitively shunted flux qubit and a transmon, and demonstrate the elimination of the ZZ interaction.
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Affiliation(s)
- Jaseung Ku
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - Xuexin Xu
- Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52428, Germany
- Jülich-Aachen Research Alliance (JARA), Fundamentals of Future Information Technologies, Jülich 52428, Germany
| | - Markus Brink
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - David C McKay
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Jared B Hertzberg
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Mohammad H Ansari
- Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52428, Germany
- Jülich-Aachen Research Alliance (JARA), Fundamentals of Future Information Technologies, Jülich 52428, Germany
| | - B L T Plourde
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
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38
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Zhao P, Xu P, Lan D, Chu J, Tan X, Yu H, Yu Y. High-Contrast ZZ Interaction Using Superconducting Qubits with Opposite-Sign Anharmonicity. PHYSICAL REVIEW LETTERS 2020; 125:200503. [PMID: 33258656 DOI: 10.1103/physrevlett.125.200503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 08/11/2020] [Indexed: 06/12/2023]
Abstract
For building a scalable quantum processor with superconducting qubits, ZZ interaction is of great concern because its residual has a crucial impact to two-qubit gate fidelity. Two-qubit gates with fidelity meeting the criterion of fault-tolerant quantum computation have been demonstrated using ZZ interaction. However, as the performance of quantum processors improves, the residual static ZZ can become a performance-limiting factor for quantum gate operation and quantum error correction. Here, we introduce a superconducting architecture using qubits with opposite-sign anharmonicity, a transmon qubit, and a C-shunt flux qubit, to address this issue. We theoretically demonstrate that by coupling the two types of qubits, the high-contrast ZZ interaction can be realized. Thus, we can control the interaction with a high on-off ratio to implement two-qubit controlled-Z gates, or suppress it during two-qubit gate operation using XY interaction (e.g., an iSWAP gate). The proposed architecture can also be scaled up to multiqubit cases. In a fixed coupled system, ZZ crosstalk related to neighboring spectator qubits could also be heavily suppressed.
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Affiliation(s)
- Peng Zhao
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 230039, China
| | - Peng Xu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 230039, China
- Institute of Quantum Information and Technology, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
- State Key Laboratory of Quantum Optics and Devices, Shanxi University, Taiyuan 030006, China
| | - Dong Lan
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 230039, China
| | - Ji Chu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 230039, China
| | - Xinsheng Tan
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 230039, China
| | - Haifeng Yu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 230039, China
| | - Yang Yu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 230039, China
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39
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Yurtalan MA, Shi J, Kononenko M, Lupascu A, Ashhab S. Implementation of a Walsh-Hadamard Gate in a Superconducting Qutrit. PHYSICAL REVIEW LETTERS 2020; 125:180504. [PMID: 33196217 DOI: 10.1103/physrevlett.125.180504] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 09/23/2020] [Indexed: 06/11/2023]
Abstract
We have implemented a Walsh-Hadamard gate, which performs a quantum Fourier transform, in a superconducting qutrit. The qutrit is encoded in the lowest three energy levels of a capacitively shunted flux device, operated at the optimal flux-symmetry point. We use an efficient decomposition of the Walsh-Hadamard gate into two unitaries, generated by off-diagonal and diagonal Hamiltonians, respectively. The gate implementation utilizes simultaneous driving of all three transitions between the three pairs of energy levels of the qutrit, one of which is implemented with a two-photon process. The gate has a duration of 35 ns and an average fidelity over a representative set of states, including preparation and tomography errors, of 99.2%, characterized with quantum-state tomography. Compensation of ac-Stark and Bloch-Siegert shifts is essential for reaching high gate fidelities.
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Affiliation(s)
- M A Yurtalan
- Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - J Shi
- Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - M Kononenko
- Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - A Lupascu
- Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - S Ashhab
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, Qatar
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40
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Yamashita T, Kim S, Kato H, Qiu W, Semba K, Fujimaki A, Terai H. π phase shifter based on NbN-based ferromagnetic Josephson junction on a silicon substrate. Sci Rep 2020; 10:13687. [PMID: 32792626 PMCID: PMC7426421 DOI: 10.1038/s41598-020-70766-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/04/2020] [Indexed: 11/08/2022] Open
Abstract
In the field of superconducting electronics, a π phase shifter based on a ferromagnetic Josephson junction is expected to provide various advantages to classical and quantum superconducting devices. Here we report niobium nitride (NbN)-based ferromagnetic π junctions on a silicon (Si) substrate with a titanium nitride (TiN) buffer layer, which have applications to flux-bias-free flux quantum bits (qubits) and classical digital logic elements. We fabricated and characterized NbN/aluminum nitride (AlN)/NbN Josephson junctions, NbN/copper nickel (CuNi)/NbN ferromagnetic Josephson junctions, and superconducting quantum interference devices (SQUIDs) consisting of these junctions on the Si substrate. The fabricated NbN/AlN/NbN junctions showed a high junction quality suitable for qubit applications. Furthermore, the magnetic field dependence of the SQUID's critical current indicated that the NbN/CuNi/NbN junction worked as a π phase shifter on the Si substrate.
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Affiliation(s)
- Taro Yamashita
- Graduate School of Engineering, Nagoya University, Nagoya, Japan.
| | - Sunmi Kim
- National Institute of Information and Communications Technology, Tokyo, Japan
| | - Haruki Kato
- Graduate School of Engineering, Nagoya University, Nagoya, Japan
| | - Wei Qiu
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe, Japan
| | - Kouichi Semba
- National Institute of Information and Communications Technology, Tokyo, Japan
| | - Akira Fujimaki
- Graduate School of Engineering, Nagoya University, Nagoya, Japan
| | - Hirotaka Terai
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe, Japan
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41
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Larsen TW, Gershenson ME, Casparis L, Kringhøj A, Pearson NJ, McNeil RPG, Kuemmeth F, Krogstrup P, Petersson KD, Marcus CM. Parity-Protected Superconductor-Semiconductor Qubit. PHYSICAL REVIEW LETTERS 2020; 125:056801. [PMID: 32794832 DOI: 10.1103/physrevlett.125.056801] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 07/09/2020] [Indexed: 06/11/2023]
Abstract
Coherence of superconducting qubits can be improved by implementing designs that protect the parity of Cooper pairs on superconducting islands. Here, we introduce a parity-protected qubit based on voltage-controlled semiconductor nanowire Josephson junctions, taking advantage of the higher harmonic content in the energy-phase relation of few-channel junctions. A symmetric interferometer formed by two such junctions, gate-tuned into balance and frustrated by a half-quantum of applied flux, yields a cos(2φ) Josephson element, reflecting coherent transport of pairs of Cooper pairs. We demonstrate that relaxation of the qubit can be suppressed tenfold by tuning into the protected regime.
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Affiliation(s)
- T W Larsen
- Center for Quantum Devices and Microsoft Quantum Lab-Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - M E Gershenson
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - L Casparis
- Center for Quantum Devices and Microsoft Quantum Lab-Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - A Kringhøj
- Center for Quantum Devices and Microsoft Quantum Lab-Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - N J Pearson
- Center for Quantum Devices and Microsoft Quantum Lab-Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
- Theoretische Physik, ETH Zurich, 8093 Zurich, Switzerland
| | - R P G McNeil
- Center for Quantum Devices and Microsoft Quantum Lab-Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - F Kuemmeth
- Center for Quantum Devices and Microsoft Quantum Lab-Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - P Krogstrup
- Center for Quantum Devices and Microsoft Quantum Lab-Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
- Microsoft Quantum Materials Lab-Copenhagen, 2800 Kongens Lyngby, Denmark
| | - K D Petersson
- Center for Quantum Devices and Microsoft Quantum Lab-Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - C M Marcus
- Center for Quantum Devices and Microsoft Quantum Lab-Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
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42
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Hauke P, Katzgraber HG, Lechner W, Nishimori H, Oliver WD. Perspectives of quantum annealing: methods and implementations. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2020; 83:054401. [PMID: 32235066 DOI: 10.1088/1361-6633/ab85b8] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Quantum annealing is a computing paradigm that has the ambitious goal of efficiently solving large-scale combinatorial optimization problems of practical importance. However, many challenges have yet to be overcome before this goal can be reached. This perspectives article first gives a brief introduction to the concept of quantum annealing, and then highlights new pathways that may clear the way towards feasible and large scale quantum annealing. Moreover, since this field of research is to a strong degree driven by a synergy between experiment and theory, we discuss both in this work. An important focus in this article is on future perspectives, which complements other review articles, and which we hope will motivate further research.
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Affiliation(s)
- Philipp Hauke
- INO-CNR BEC Center and Department of Physics, University of Trento, 38123Povo (TN), Italy. Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg, Germany. Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany
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43
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Projecting an ultra-strongly-coupled system in a non-energy-eigenbasis with a driven nonlinear resonator. Sci Rep 2020; 10:1751. [PMID: 32019941 PMCID: PMC7000414 DOI: 10.1038/s41598-019-56866-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 12/02/2019] [Indexed: 11/22/2022] Open
Abstract
We explore the problem of projecting the ground-state of an ultra-strong-coupled circuit-QED system into a non-energy-eigenstate. As a measurement apparatus we consider a nonlinear driven resonator. We find that the post-measurement state of the nonlinear resonator exhibits a large correlation with the post-measurement state of the ultra-strongly coupled system even when the coupling between measurement device and system is much smaller than the energy scales of the system itself. While the projection is imperfect, we argue that because of the strong nonlinear response of the resonator it works in a practical regime where a linear measurement apparatus would fail.
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44
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Layden D, Chen M, Cappellaro P. Efficient Quantum Error Correction of Dephasing Induced by a Common Fluctuator. PHYSICAL REVIEW LETTERS 2020; 124:020504. [PMID: 32004019 DOI: 10.1103/physrevlett.124.020504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Indexed: 06/10/2023]
Abstract
Quantum error correction is expected to be essential in large-scale quantum technologies. However, the substantial overhead of qubits it requires is thought to greatly limit its utility in smaller, near-term devices. Here we introduce a new family of special-purpose quantum error-correcting codes that offer an exponential reduction in overhead compared to the usual repetition code. They are tailored for a common and important source of decoherence in current experiments, whereby a register of qubits is subject to phase noise through coupling to a common fluctuator, such as a resonator or a spin defect. The smallest instance encodes one logical qubit into two physical qubits, and corrects decoherence to leading-order using a constant number of one- and two-qubit operations. More generally, while the repetition code on n qubits corrects errors to order t^{O(n)}, with t the time between recoveries, our codes correct to order t^{O(2^{n})}. Moreover, they are robust to model imperfections in small- and intermediate-scale devices, where they already provide substantial gains in error suppression. As a result, these hardware-efficient codes open a potential avenue for useful quantum error correction in near-term, pre-fault tolerant devices.
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Affiliation(s)
- David Layden
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Mo Chen
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Paola Cappellaro
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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45
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Quantum supremacy using a programmable superconducting processor. Nature 2019; 574:505-510. [PMID: 31645734 DOI: 10.1038/s41586-019-1666-5] [Citation(s) in RCA: 819] [Impact Index Per Article: 163.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 09/20/2019] [Indexed: 11/08/2022]
Abstract
The promise of quantum computers is that certain computational tasks might be executed exponentially faster on a quantum processor than on a classical processor1. A fundamental challenge is to build a high-fidelity processor capable of running quantum algorithms in an exponentially large computational space. Here we report the use of a processor with programmable superconducting qubits2-7 to create quantum states on 53 qubits, corresponding to a computational state-space of dimension 253 (about 1016). Measurements from repeated experiments sample the resulting probability distribution, which we verify using classical simulations. Our Sycamore processor takes about 200 seconds to sample one instance of a quantum circuit a million times-our benchmarks currently indicate that the equivalent task for a state-of-the-art classical supercomputer would take approximately 10,000 years. This dramatic increase in speed compared to all known classical algorithms is an experimental realization of quantum supremacy8-14 for this specific computational task, heralding a much-anticipated computing paradigm.
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46
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Liu T, Zhang Y, Guo BQ, Yu CS, Zhang WN. Creation of superposition of arbitrary states encoded in two high-Q cavities. OPTICS EXPRESS 2019; 27:27168-27182. [PMID: 31674583 DOI: 10.1364/oe.27.027168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/18/2019] [Indexed: 06/10/2023]
Abstract
The principle of superposition is a key ingredient for quantum mechanics. A recent work [Phys. Rev. Lett.116, 110403 (2016)10.1103/PhysRevLett.116.110403] has shown that a quantum adder that deterministically generates a superposition of two unknown states is forbidden. Here we consider the implementation of the probabilistic quantum adder in the 3D cavity-transmon system. Our implementation is based on a three-level superconducting transmon qubit dispersively coupled to two cavities. Numerical simulations show that high-fidelity generation of the superposition of two coherent states is feasible with current circuit QED technology. Our method also works for other physical systems such as two optical cavities coupled to a three-level atom or two nitrogen-vacancy center ensembles interacted with one three-level superconducting flux qubit.
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47
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Sung Y, Beaudoin F, Norris LM, Yan F, Kim DK, Qiu JY, von Lüpke U, Yoder JL, Orlando TP, Gustavsson S, Viola L, Oliver WD. Non-Gaussian noise spectroscopy with a superconducting qubit sensor. Nat Commun 2019; 10:3715. [PMID: 31527608 PMCID: PMC6746758 DOI: 10.1038/s41467-019-11699-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 07/30/2019] [Indexed: 11/17/2022] Open
Abstract
Accurate characterization of the noise influencing a quantum system of interest has far-reaching implications across quantum science, ranging from microscopic modeling of decoherence dynamics to noise-optimized quantum control. While the assumption that noise obeys Gaussian statistics is commonly employed, noise is generically non-Gaussian in nature. In particular, the Gaussian approximation breaks down whenever a qubit is strongly coupled to discrete noise sources or has a non-linear response to the environmental degrees of freedom. Thus, in order to both scrutinize the applicability of the Gaussian assumption and capture distinctive non-Gaussian signatures, a tool for characterizing non-Gaussian noise is essential. Here, we experimentally validate a quantum control protocol which, in addition to the spectrum, reconstructs the leading higher-order spectrum of engineered non-Gaussian dephasing noise using a superconducting qubit as a sensor. This first experimental demonstration of non-Gaussian noise spectroscopy represents a major step toward demonstrating a complete spectral estimation toolbox for quantum devices.
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Affiliation(s)
- Youngkyu Sung
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Félix Beaudoin
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH, 03755, USA
- NanoAcademic Technologies, 666 rue Sherbrooke Ouest, Suite 802, Montreal, Quebec, H3A 1E7, Canada
| | - Leigh M Norris
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH, 03755, USA
| | - Fei Yan
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - David K Kim
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, MA, 02421, USA
| | - Jack Y Qiu
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Uwe von Lüpke
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Jonilyn L Yoder
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, MA, 02421, USA
| | - Terry P Orlando
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Lorenza Viola
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH, 03755, USA.
| | - William D Oliver
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- MIT Lincoln Laboratory, 244 Wood Street, Lexington, MA, 02421, USA.
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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48
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Paolucci F, Vischi F, De Simoni G, Guarcello C, Solinas P, Giazotto F. Field-Effect Controllable Metallic Josephson Interferometer. NANO LETTERS 2019; 19:6263-6269. [PMID: 31461290 DOI: 10.1021/acs.nanolett.9b02369] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Gate-tunable Josephson junctions (JJs) are the backbone of superconducting classical and quantum computation. Typically, these systems exploit low-charge-concentration materials and present technological difficulties limiting their scalability. Surprisingly, electric field modulation of a supercurrent in metallic wires and JJs has been recently demonstrated. Here, we report the realization of titanium-based monolithic interferometers which allow tuning both JJs independently via voltage bias applied to capacitively coupled electrodes. Our experiments demonstrate full control of the amplitude of the switching current (Is) and of the superconducting phase across the single JJ in a wide range of temperatures. Astoundingly, by gate-biasing a single junction, the maximum achievable total Is is suppressed down to values much lower than the critical current of a single JJ. A theoretical model including gate-induced phase fluctuations on a single junction accounts for our experimental findings. This class of quantum interferometers could represent a breakthrough for several applications such as digital electronics, quantum computing, sensitive magnetometry, and single-photon detection.
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Affiliation(s)
- Federico Paolucci
- INFN Sezione di Pisa , Largo Bruno Pontecorvo 3 , I-56127 Pisa , Italy
- NEST , Instituto Nanoscienze-CNR and Scuola Normale Superiore , I-56127 Pisa , Italy
| | - Francesco Vischi
- NEST , Instituto Nanoscienze-CNR and Scuola Normale Superiore , I-56127 Pisa , Italy
- Dipartimento di Fisica , Università di Pisa , Largo Pontecorvo 3 , I-56127 Pisa , Italy
| | - Giorgio De Simoni
- NEST , Instituto Nanoscienze-CNR and Scuola Normale Superiore , I-56127 Pisa , Italy
| | - Claudio Guarcello
- NEST , Instituto Nanoscienze-CNR and Scuola Normale Superiore , I-56127 Pisa , Italy
| | - Paolo Solinas
- SPIN-CNR , Via Dodecaneso 33 , I-16146 Genova , Italy
| | - Francesco Giazotto
- NEST , Instituto Nanoscienze-CNR and Scuola Normale Superiore , I-56127 Pisa , Italy
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49
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Houzet M, Serniak K, Catelani G, Devoret MH, Glazman LI. Photon-Assisted Charge-Parity Jumps in a Superconducting Qubit. PHYSICAL REVIEW LETTERS 2019; 123:107704. [PMID: 31573281 DOI: 10.1103/physrevlett.123.107704] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Indexed: 06/10/2023]
Abstract
We evaluate the rates of energy and phase relaxation of a superconducting qubit caused by stray photons with energy exceeding the threshold for breaking a Cooper pair. All channels of relaxation within this mechanism are associated with the change in the charge parity of the qubit, enabling the separation of the photon-assisted processes from other contributions to the relaxation rates. Among the signatures of the new mechanism is the same order of rates of the transitions in which a qubit loses or gains energy, which is in agreement with recent experiments. Our theory offers the possibility to characterize the electromagnetic environment of superconducting devices at the single-photon level for frequencies above the superconducting gap.
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Affiliation(s)
- M Houzet
- Univ. Grenoble Alpes, CEA, IRIG-Pheliqs, F-38000 Grenoble, France
| | - K Serniak
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - G Catelani
- JARA Institute for Quantum Information (PGI-11), Forschungszentrum Jülich, 52425 Jülich, Germany
- Yale Quantum Institute, Yale University, New Haven, Connecticut 06520, USA
| | - M H Devoret
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - L I Glazman
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
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50
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Grünhaupt L, Spiecker M, Gusenkova D, Maleeva N, Skacel ST, Takmakov I, Valenti F, Winkel P, Rotzinger H, Wernsdorfer W, Ustinov AV, Pop IM. Granular aluminium as a superconducting material for high-impedance quantum circuits. NATURE MATERIALS 2019; 18:816-819. [PMID: 31036961 DOI: 10.1038/s41563-019-0350-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 03/18/2019] [Indexed: 06/09/2023]
Abstract
Superconducting quantum information processing machines are predominantly based on microwave circuits with relatively low characteristic impedance, about 100 Ω, and small anharmonicity, which can limit their coherence and logic gate fidelity1,2. A promising alternative is circuits based on so-called superinductors3-6, with characteristic impedances exceeding the resistance quantum RQ = 6.4 kΩ. However, previous implementations of superinductors, consisting of mesoscopic Josephson junction arrays7,8, can introduce unintended nonlinearity or parasitic resonant modes in the qubit vicinity, degrading its coherence. Here, we present a fluxonium qubit design based on a granular aluminium superinductor strip9-11. We show that granular aluminium can form an effective junction array with high kinetic inductance and be in situ integrated with standard aluminium circuit processing. The measured qubit coherence time [Formula: see text] illustrates the potential of granular aluminium for applications ranging from protected qubit designs to quantum-limited amplifiers and detectors.
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Affiliation(s)
- Lukas Grünhaupt
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Martin Spiecker
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Daria Gusenkova
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Nataliya Maleeva
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Sebastian T Skacel
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Ivan Takmakov
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
- Russian Quantum Center, National University of Science and Technology MISIS, Moscow, Russia
| | - Francesco Valenti
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Institute for Data Processing and Electronics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Patrick Winkel
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Hannes Rotzinger
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Wolfgang Wernsdorfer
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Alexey V Ustinov
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Russian Quantum Center, National University of Science and Technology MISIS, Moscow, Russia
| | - Ioan M Pop
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany.
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany.
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