1
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Peculiarities of Electron Wave Packet Dynamics in Planar Nanostructures in the Presence of Magnetic and Electric Fields. Symmetry (Basel) 2022. [DOI: 10.3390/sym14102215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Currently, spatially localized electron densities and currents are considered to be candidates for use in the encoding of quantum information. For this reason, the control of their temporal dynamics is an important task. In this work, the spatiotemporal evolution of an electron wave packet in planar nanostructure in the presence of transverse magnetic and lateral electric fields is investigated by direct analytical solution of the non-stationary Schrödinger equation. Methods to control and manage the dynamics of the spatially localized electron density distribution are developed. The production of photon-like quantum states of electrons opens up opportunities for applications similar to quantum optical and quantum information technologies but implemented with charge carriers. Quantum control of the trajectory of the electron wave packet, accompanied by dramatic suppression of its spreading, is demonstrated. This study discovered methods to manage spatially localized electron behavior in a nanostructure that allows a controllable charge quantum transfer and gives rise to new prospects for quantum nanoelectronics technology.
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2
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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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3
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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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4
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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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5
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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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6
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Popolitova DV, Klenov NV, Soloviev II, Bakurskiy SV, Tikhonova OV. Unipolar magnetic field pulses as an advantageous tool for ultrafast operations in superconducting Josephson "atoms". BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:1548-1558. [PMID: 31467819 PMCID: PMC6693414 DOI: 10.3762/bjnano.10.152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 07/12/2019] [Indexed: 06/10/2023]
Abstract
A theoretical approach to the consistent full quantum description of the ultrafast population transfer and magnetization reversal in superconducting meta-atoms induced by picosecond unipolar pulses of a magnetic field is developed. A promising scheme based on the regime of stimulated Raman Λ-type transitions between qubit states via upper-lying levels is suggested in order to provide ultrafast quantum operations on the picosecond time scale. The experimental realization of a circuit-on-chip for the discussed ultrafast control is presented.
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Affiliation(s)
- Daria V Popolitova
- Lomonosov Moscow State University Physics Department, Moscow, 119991, Russia
| | - Nikolay V Klenov
- Lomonosov Moscow State University Physics Department, Moscow, 119991, Russia
- All-Russian Research Institute of Automatics n.a. N.L. Dukhov (VNIIA), 127055, Moscow, Russia
- Moscow Technical University of Communications and Informatics (MTUCI), 111024 Moscow, Russia
| | - Igor I Soloviev
- All-Russian Research Institute of Automatics n.a. N.L. Dukhov (VNIIA), 127055, Moscow, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, 119991, Russia
| | - Sergey V Bakurskiy
- All-Russian Research Institute of Automatics n.a. N.L. Dukhov (VNIIA), 127055, Moscow, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, 119991, Russia
| | - Olga V Tikhonova
- Lomonosov Moscow State University Physics Department, Moscow, 119991, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, 119991, Russia
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7
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Bin Q, Lü XY, Bin SW, Zhu GL, Wu Y. Single-photon-induced two qubits excitation without breaking parity symmetry. OPTICS EXPRESS 2017; 25:31718-31729. [PMID: 29245843 DOI: 10.1364/oe.25.031718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/28/2017] [Indexed: 06/07/2023]
Abstract
We investigate theoretically the model of two "qubits" system (one qubit having an auxiliary level) interacting with a single-mode resonator in the ultrastrong coupling regime. We show that a single photon could simultaneously excite two qubits without breaking the parity symmetry of system by properly encoding the excited states of qubits. The optimal parameter regime for achieving high probability approaching one is identified in the case of ignoring the system dissipation. Moreover, using experimentally feasible parameters, we also analyze the dissipation dynamics of the system, and present the realization of two-qubit excitation induced by single-photon. This work offers an alternative approach to realize the single-photon-induced two qubits excitation, which should advance the development of single-photon quantum technologies and have potential applications in quantum information science.
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8
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Wendin G. Quantum information processing with superconducting circuits: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:106001. [PMID: 28682303 DOI: 10.1088/1361-6633/aa7e1a] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
During the last ten years, superconducting circuits have passed from being interesting physical devices to becoming contenders for near-future useful and scalable quantum information processing (QIP). Advanced quantum simulation experiments have been shown with up to nine qubits, while a demonstration of quantum supremacy with fifty qubits is anticipated in just a few years. Quantum supremacy means that the quantum system can no longer be simulated by the most powerful classical supercomputers. Integrated classical-quantum computing systems are already emerging that can be used for software development and experimentation, even via web interfaces. Therefore, the time is ripe for describing some of the recent development of superconducting devices, systems and applications. As such, the discussion of superconducting qubits and circuits is limited to devices that are proven useful for current or near future applications. Consequently, the centre of interest is the practical applications of QIP, such as computation and simulation in Physics and Chemistry.
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Affiliation(s)
- G Wendin
- Department of Microtechnology and Nanoscience-MC2, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
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9
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Yan F, Gustavsson S, Kamal A, Birenbaum J, Sears AP, Hover D, Gudmundsen TJ, Rosenberg D, Samach G, Weber S, Yoder JL, Orlando TP, Clarke J, Kerman AJ, Oliver WD. The flux qubit revisited to enhance coherence and reproducibility. Nat Commun 2016; 7:12964. [PMID: 27808092 PMCID: PMC5097147 DOI: 10.1038/ncomms12964] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 08/19/2016] [Indexed: 11/09/2022] Open
Abstract
The scalable application of quantum information science will stand on reproducible and controllable high-coherence quantum bits (qubits). Here, we revisit the design and fabrication of the superconducting flux qubit, achieving a planar device with broad-frequency tunability, strong anharmonicity, high reproducibility and relaxation times in excess of 40 μs at its flux-insensitive point. Qubit relaxation times T1 across 22 qubits are consistently matched with a single model involving resonator loss, ohmic charge noise and 1/f-flux noise, a noise source previously considered primarily in the context of dephasing. We furthermore demonstrate that qubit dephasing at the flux-insensitive point is dominated by residual thermal-photons in the readout resonator. The resulting photon shot noise is mitigated using a dynamical decoupling protocol, resulting in T2≈85 μs, approximately the 2T1 limit. In addition to realizing an improved flux qubit, our results uniquely identify photon shot noise as limiting T2 in contemporary qubits based on transverse qubit-resonator interaction.
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Affiliation(s)
- Fei Yan
- Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Simon Gustavsson
- Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Archana Kamal
- Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jeffrey Birenbaum
- Department of Physics, University of California, Berkeley, California 94720-7300, USA
| | - Adam P Sears
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - David Hover
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Ted J. Gudmundsen
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Danna Rosenberg
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Gabriel Samach
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - S Weber
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Jonilyn L. Yoder
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - Terry P. Orlando
- Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - John Clarke
- Department of Physics, University of California, Berkeley, California 94720-7300, USA
| | - Andrew J. Kerman
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
| | - William D. Oliver
- Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- MIT Lincoln Laboratory, Quantum Information and Integrated Nanosystems Group, 244 Wood Street, Lexington, Massachusetts 02420, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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10
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Learning robust pulses for generating universal quantum gates. Sci Rep 2016; 6:36090. [PMID: 27782219 PMCID: PMC5080597 DOI: 10.1038/srep36090] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 10/10/2016] [Indexed: 11/08/2022] Open
Abstract
Constructing a set of universal quantum gates is a fundamental task for quantum computation. The existence of noises, disturbances and fluctuations is unavoidable during the process of implementing quantum gates for most practical quantum systems. This paper employs a sampling-based learning method to find robust control pulses for generating a set of universal quantum gates. Numerical results show that the learned robust control fields are insensitive to disturbances, uncertainties and fluctuations during the process of realizing universal quantum gates.
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11
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Qiu Y, Xiong W, He XL, Li TF, You JQ. Four-junction superconducting circuit. Sci Rep 2016; 6:28622. [PMID: 27356619 PMCID: PMC4928057 DOI: 10.1038/srep28622] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/06/2016] [Indexed: 11/24/2022] Open
Abstract
We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit.
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Affiliation(s)
- Yueyin Qiu
- Department of Physics, Fudan University, Shanghai 200433, China
- Beijing Computational Science Research Center, Beijing 100193, China
| | - Wei Xiong
- Department of Physics, Fudan University, Shanghai 200433, China
- Beijing Computational Science Research Center, Beijing 100193, China
| | - Xiao-Ling He
- School of Science, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310023, China
| | - Tie-Fu Li
- Beijing Computational Science Research Center, Beijing 100193, China
- Institute of Microelectronics, Department of Microelectronics and Nanoelectronics and Tsinghua National Laboratory of Information Science and Technology, Tsinghua University, Beijing 100084, China
| | - J. Q. You
- Beijing Computational Science Research Center, Beijing 100193, China
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12
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Dong D, Chen C, Qi B, Petersen IR, Nori F. Robust manipulation of superconducting qubits in the presence of fluctuations. Sci Rep 2015; 5:7873. [PMID: 25598529 PMCID: PMC4297962 DOI: 10.1038/srep07873] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 12/12/2014] [Indexed: 11/09/2022] Open
Abstract
Superconducting quantum systems are promising candidates for quantum information processing due to their scalability and design flexibility. However, the existence of defects, fluctuations, and inaccuracies is unavoidable for practical superconducting quantum circuits. In this paper, a sampling-based learning control (SLC) method is used to guide the design of control fields for manipulating superconducting quantum systems. Numerical results for one-qubit systems and coupled two-qubit systems show that the "smart" fields learned using the SLC method can achieve robust manipulation of superconducting qubits, even in the presence of large fluctuations and inaccuracies.
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Affiliation(s)
- Daoyi Dong
- School of Engineering and Information Technology, University of New South Wales, Canberra 2600, Australia
| | - Chunlin Chen
- Department of Control and System Engineering, School of Management and Engineering, Nanjing University, Nanjing 210093, China
| | - Bo Qi
- Key Laboratory of Systems and Control, ISS, and National Center for Mathematics and Interdis-ciplinary Sciences, Academy of Mathematics and Systems Science, CAS, Beijing 100190, China
| | - Ian R Petersen
- School of Engineering and Information Technology, University of New South Wales, Canberra 2600, Australia
| | - Franco Nori
- 1] CEMS, RIKEN, Saitama351-0198, Japan [2] Physics Department, The University of Michigan, Ann Arbor, Michigan 48109-1040, USA
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13
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Klenov NV, Kuznetsov AV, Soloviev II, Bakurskiy SV, Tikhonova OV. Magnetic reversal dynamics of a quantum system on a picosecond timescale. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2015; 6:1946-56. [PMID: 26665066 PMCID: PMC4660925 DOI: 10.3762/bjnano.6.199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 09/04/2015] [Indexed: 05/14/2023]
Abstract
We present our approach for a consistent, fully quantum mechanical description of the magnetization reversal process in natural and artificial atomic systems by means of short magnetic pulses. In terms of the simplest model of a two-level system with a magnetic moment, we analyze the possibility of a fast magnetization reversal on the picosecond timescale induced by oscillating or short unipolar magnetic pulses. We demonstrate the possibility of selective magnetization reversal of a superconducting flux qubit using a single flux quantum-based pulse and suggest a promising, rapid Λ-scheme for resonant implementation of this process. In addition, the magnetization reversal treatment is fulfilled within the framework of the macroscopic theory of the magnetic moment, which allows for the comparison and explanation of the quantum and classical behavior.
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Affiliation(s)
- Nikolay V Klenov
- Lomonosov Moscow State University Physics Department, Moscow 119991, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow 119991, Russia
- Lukin Scientific Research Institute of Physical Problems, Zelenograd, Moscow 124460, Russia
- Moscow Institute of Physics and Technology, State University, Dolgoprudniy, Moscow Region, Russia
| | - Alexey V Kuznetsov
- Lomonosov Moscow State University Physics Department, Moscow 119991, Russia
| | - Igor I Soloviev
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow 119991, Russia
- Lukin Scientific Research Institute of Physical Problems, Zelenograd, Moscow 124460, Russia
- Moscow Institute of Physics and Technology, State University, Dolgoprudniy, Moscow Region, Russia
| | - Sergey V Bakurskiy
- Lomonosov Moscow State University Physics Department, Moscow 119991, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow 119991, Russia
| | - Olga V Tikhonova
- Lomonosov Moscow State University Physics Department, Moscow 119991, Russia
- Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow 119991, Russia
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14
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Encoding a qubit with Majorana modes in superconducting circuits. Sci Rep 2014; 4:5535. [PMID: 24985708 PMCID: PMC4078313 DOI: 10.1038/srep05535] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 06/16/2014] [Indexed: 11/08/2022] Open
Abstract
Majorana fermions are long-sought exotic particles that are their own antiparticles. Here we propose to utilize superconducting circuits to construct two superconducting-qubit arrays where Majorana modes can occur. A so-called Majorana qubit is encoded by using the unpaired Majorana modes, which emerge at the left and right ends of the chain in the Majorana-fermion representation. We also show this Majorana qubit in the spin representation and its advantage, over a single superconducting qubit, regarding quantum coherence. Moreover, we propose to use four superconducting qubits as the smallest system to demonstrate the braiding of Majorana modes and show how the states before and after braiding Majoranas can be discriminated.
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15
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Devoret MH, Schoelkopf RJ. Superconducting Circuits for Quantum Information: An Outlook. Science 2013; 339:1169-74. [DOI: 10.1126/science.1231930] [Citation(s) in RCA: 1301] [Impact Index Per Article: 118.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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16
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Adhikari P, Hafezi M, Taylor JM. Nonlinear optics quantum computing with circuit QED. PHYSICAL REVIEW LETTERS 2013; 110:060503. [PMID: 23432228 DOI: 10.1103/physrevlett.110.060503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Indexed: 06/01/2023]
Abstract
One approach to quantum information processing is to use photons as quantum bits and rely on linear optical elements for most operations. However, some optical nonlinearity is necessary to enable universal quantum computing. Here, we suggest a circuit-QED approach to nonlinear optics quantum computing in the microwave regime, including a deterministic two-photon phase gate. Our specific example uses a hybrid quantum system comprising a LC resonator coupled to a superconducting flux qubit to implement a nonlinear coupling. Compared to the self-Kerr nonlinearity, we find that our approach has improved tolerance to noise in the qubit while maintaining fast operation.
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Affiliation(s)
- Prabin Adhikari
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
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17
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Chow JM, Córcoles AD, Gambetta JM, Rigetti C, Johnson BR, Smolin JA, Rozen JR, Keefe GA, Rothwell MB, Ketchen MB, Steffen M. Simple all-microwave entangling gate for fixed-frequency superconducting qubits. PHYSICAL REVIEW LETTERS 2011; 107:080502. [PMID: 21929152 DOI: 10.1103/physrevlett.107.080502] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Indexed: 05/31/2023]
Abstract
We demonstrate an all-microwave two-qubit gate on superconducting qubits which are fixed in frequency at optimal bias points. The gate requires no additional subcircuitry and is tunable via the amplitude of microwave irradiation on one qubit at the transition frequency of the other. We use the gate to generate entangled states with a maximal extracted concurrence of 0.88, and quantum process tomography reveals a gate fidelity of 81%.
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Affiliation(s)
- Jerry M Chow
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
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Forn-Díaz P, Lisenfeld J, Marcos D, García-Ripoll JJ, Solano E, Harmans CJPM, Mooij JE. Observation of the Bloch-Siegert shift in a qubit-oscillator system in the ultrastrong coupling regime. PHYSICAL REVIEW LETTERS 2010; 105:237001. [PMID: 21231496 DOI: 10.1103/physrevlett.105.237001] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Indexed: 05/30/2023]
Abstract
We measure the dispersive energy-level shift of an LC resonator magnetically coupled to a superconducting qubit, which clearly shows that our system operates in the ultrastrong coupling regime. The large mutual kinetic inductance provides a coupling energy of ≈ 0.82 GHz, requiring the addition of counter-rotating-wave terms in the description of the Jaynes-Cummings model. We find a 50 MHz Bloch-Siegert shift when the qubit is in its symmetry point, fully consistent with our analytical model.
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Affiliation(s)
- P Forn-Díaz
- Quantum Transport Group, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands
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Marcos D, Wubs M, Taylor JM, Aguado R, Lukin MD, Sørensen AS. Coupling nitrogen-vacancy centers in diamond to superconducting flux qubits. PHYSICAL REVIEW LETTERS 2010; 105:210501. [PMID: 21231275 DOI: 10.1103/physrevlett.105.210501] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Indexed: 05/30/2023]
Abstract
We propose a method to achieve coherent coupling between nitrogen-vacancy (NV) centers in diamond and superconducting (SC) flux qubits. The resulting coupling can be used to create a coherent interaction between the spin states of distant NV centers mediated by the flux qubit. Furthermore, the magnetic coupling can be used to achieve a coherent transfer of quantum information between the flux qubit and an ensemble of NV centers. This enables a long-term memory for a SC quantum processor and possibly an interface between SC qubits and light.
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Affiliation(s)
- D Marcos
- Theory and Simulation of Materials Department, Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco 28049, Madrid, Spain
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