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Brosco V, Serpico G, Vinokur V, Poccia N, Vool U. Superconducting Qubit Based on Twisted Cuprate Van der Waals Heterostructures. PHYSICAL REVIEW LETTERS 2024; 132:017003. [PMID: 38242651 DOI: 10.1103/physrevlett.132.017003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 12/05/2023] [Accepted: 12/07/2023] [Indexed: 01/21/2024]
Abstract
Van-der-Waals assembly enables the fabrication of novel Josephson junctions featuring an atomically sharp interface between two exfoliated and relatively twisted Bi_{2}Sr_{2}CaCu_{2}O_{8+x} (Bi2212) flakes. In a range of twist angles around 45°, the junction provides a regime where the interlayer two-Cooper pair tunneling dominates the current-phase relation. Here we propose employing this novel junction to realize a capacitively shunted qubit that we call flowermon. The d-wave nature of the order parameter endows the flowermon with inherent protection against charge-noise-induced relaxation and quasiparticle-induced dissipation. This inherently protected qubit paves the way to a new class of high-coherence hybrid superconducting quantum devices based on unconventional superconductors.
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Affiliation(s)
- Valentina Brosco
- Institute for Complex Systems (ISC) Consiglio Nazionale delle Ricerche and Physics Department University of Rome, "La Sapienza," Piazzale Aldo Moro, 2, 00185 Roma, Italy
- Centro Ricerche Enrico Fermi, Piazza del Viminale, 1, I-00184 Rome, Italy
| | - Giuseppe Serpico
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Department of Physics, University of Naples Federico II, Via Cintia, Naples 80126, Italy
| | - Valerii Vinokur
- Terra Quantum AG, Kornhausstrasse 25, CH-9000 St. Gallen, Switzerland
- Physics Department, CUNY, City College of City University of New York, 160 Convent Avenue, New York, New York 10031, USA
| | - Nicola Poccia
- Leibniz Institute for Solid State and Materials Science Dresden (IFW Dresden), 01069 Dresden, Germany
| | - Uri Vool
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
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Steinhuber M, Schlagheck P, Urbina JD, Richter K. Dynamical transition from localized to uniform scrambling in locally hyperbolic systems. Phys Rev E 2023; 108:024216. [PMID: 37723671 DOI: 10.1103/physreve.108.024216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 07/23/2023] [Indexed: 09/20/2023]
Abstract
Fast scrambling of quantum correlations, reflected by the exponential growth of out-of-time-order correlators (OTOCs) on short pre-Ehrenfest time scales, is commonly considered as a major quantum signature of unstable dynamics in quantum systems with a classical limit. In two recent works [Phys. Rev. Lett. 123, 160401 (2019)0031-900710.1103/PhysRevLett.123.160401] and [Phys. Rev. Lett. 124, 140602 (2020)10.1103/PhysRevLett.124.140602], a significant difference in the scrambling rate of integrable (many-body) systems was observed, depending on the initial state being semiclassically localized around unstable fixed points or fully delocalized (infinite temperature). Specifically, the quantum Lyapunov exponent λ_{q} quantifying the OTOC growth is given, respectively, by λ_{q}=2λ_{s} or λ_{q}=λ_{s} in terms of the stability exponent λ_{s} of the hyperbolic fixed point. Here we show that a wave packet, initially localized around this fixed point, features a distinct dynamical transition between these two regions. We present an analytical semiclassical approach providing a physical picture of this phenomenon, and support our findings by extensive numerical simulations in the whole parameter range of locally unstable dynamics of a Bose-Hubbard dimer. Our results suggest that the existence of this crossover is a hallmark of unstable separatrix dynamics in integrable systems, thus opening the possibility to distinguish the latter, on the basis of this particular observable, from genuine chaotic dynamics generally featuring uniform exponential growth of the OTOC.
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Affiliation(s)
- Mathias Steinhuber
- Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany
| | | | - Juan Diego Urbina
- Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany
| | - Klaus Richter
- Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany
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Sun Z, Kaneko T, Golež D, Millis AJ. Second-Order Josephson Effect in Excitonic Insulators. PHYSICAL REVIEW LETTERS 2021; 127:127702. [PMID: 34597072 DOI: 10.1103/physrevlett.127.127702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 08/03/2021] [Indexed: 06/13/2023]
Abstract
We show that in electron-hole bilayers with excitonic orders arising from conduction and valence bands formed by atomic orbitals that have different parities, nonzero interlayer tunneling leads to a second-order Josephson effect. This means the interlayer electrical current is related to the phase of the excitonic order parameter as J=J_{c}sin2θ instead of J=J_{c}sinθ and that the system has two degenerate ground states at θ=0,π that can be switched by an interlayer voltage pulse. When generalized to a three dimensional stack of alternating electron-hole planes or a two dimensional stack of chains, the ac Josephson effect implies that electric field pulses perpendicular to the layers and chains can steer the order parameter phase between the two degenerate ground states, making these devices ultrafast memories. The order parameter steering also applies to the excitonic insulator candidate Ta_{2}NiSe_{5}.
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Affiliation(s)
- Zhiyuan Sun
- Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027, USA
| | - Tatsuya Kaneko
- Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027, USA
| | - Denis Golež
- Center for Computational Quantum Physics, Flatiron Institute, 162 5th Avenue, New York, New York 10010, USA
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Andrew J Millis
- Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027, USA
- Center for Computational Quantum Physics, Flatiron Institute, 162 5th Avenue, New York, New York 10010, USA
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Pal S, Benjamin C. Tuning the 0 - π Josephson junction with a magnetic impurity: Role of tunnel contacts, exchange coupling, e - e interactions and high-spin states. Sci Rep 2018; 8:5208. [PMID: 29581475 PMCID: PMC5979961 DOI: 10.1038/s41598-018-23517-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 03/14/2018] [Indexed: 11/16/2022] Open
Abstract
We propose Josephson junction with a high-spin magnetic impurity sandwiched between two superconductors. This system shows a π junction behavior as a function of the spin magnetic moment state of the impurity, the interface transparency, exchange coupling and electron-electron interactions in the system. The system is theoretically analyzed for possible reason behind the π shift. The crucial role of spin flip scattering is highlighted. Possible applications in quantum computation of our proposed tunable high spin magnetic impurity π junction is underscored.
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Affiliation(s)
- Subhajit Pal
- School of Physical Sciences, National Institute of Science Education & Research, HBNI, Jatni, 752050, India
| | - Colin Benjamin
- School of Physical Sciences, National Institute of Science Education & Research, HBNI, Jatni, 752050, India.
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Bauch T, Lombardi F, Tafuri F, Barone A, Rotoli G, Delsing P, Claeson T. Macroscopic quantum tunneling in d-wave YBa2Cu3O7-delta Josephson junctions. PHYSICAL REVIEW LETTERS 2005; 94:087003. [PMID: 15783922 DOI: 10.1103/physrevlett.94.087003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2004] [Indexed: 05/24/2023]
Abstract
The escape rate from the zero voltage state in a superconducting Josephson junction (JJ) is determined by the temperature, but it saturates at low temperature due to macroscopic quantum tunneling (MQT). Complications due to d-wave symmetry in a high temperature superconductor, like low energy quasiparticles and an unconventional current-phase relation, may influence the escape rate. We report, for the first time to our knowledge, the observation of MQT in a YBa(2)Cu(3)O(7-delta) grain boundary biepitaxial JJ. This proves that dissipation can be significantly reduced by a proper junction configuration, which is of significance for quantum coherence.
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Affiliation(s)
- T Bauch
- Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-412 96 Göteborg, Sweden
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Amin MHS, Smirnov AY. Quasiparticle decoherence in d-wave superconducting qubits. PHYSICAL REVIEW LETTERS 2004; 92:017001. [PMID: 14754010 DOI: 10.1103/physrevlett.92.017001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2003] [Indexed: 05/24/2023]
Abstract
It is usually argued that the presence of gapless quasiparticle excitations at the nodes of the d-wave superconducting gap should strongly decohere the quantum states of a d-wave qubit, making quantum effects practically unobservable. Using a self-consistent linear response nonequilibrium quasiclassical formalism, we show that this is not necessarily true. We find quasiparticle conductance of a d-wave grain boundary junction to be strongly phase dependent. Midgap states as well as nodal quasiparticles contribute to the conductance and therefore decoherence. Quantum behavior is estimated to be detectable in a qubit containing a d-wave junction with appropriate parameters.
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Affiliation(s)
- M H S Amin
- D-Wave Systems Inc, 320-1985 W Broadway, Vancouver, British Columbia, Canada V6J 4Y3
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Lindström T, Charlebois SA, Tzalenchuk AY, Ivanov Z, Amin MHS, Zagoskin AM. Dynamical effects of an unconventional current-phase relation in YBCO dc SQUIDs. PHYSICAL REVIEW LETTERS 2003; 90:117002. [PMID: 12688956 DOI: 10.1103/physrevlett.90.117002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2002] [Indexed: 05/24/2023]
Abstract
The predominant d-wave pairing symmetry in high-temperature superconductors allows for a variety of current-phase relations in Josephson junctions, which is to a certain degree fabrication controlled. In this Letter, we report on direct experimental observations of the effects of a nonsinusoidal current-phase dependence in YBCO dc SQUIDs, which agree with the theoretical description of the system.
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Affiliation(s)
- T Lindström
- Department of Microelectronics and Nanoscience, Chalmers University of Technology and Göteborg University, Sweden.
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Baselmans JJA, Heikkilä TT, van Wees BJ, Klapwijk TM. Direct observation of the transition from the conventional superconducting state to the pi state in a controllable Josephson junction. PHYSICAL REVIEW LETTERS 2002; 89:207002. [PMID: 12443501 DOI: 10.1103/physrevlett.89.207002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2002] [Indexed: 05/24/2023]
Abstract
We measure the full supercurrent-phase relation of a controllable pi junction around the transition from the conventional 0 state to the pi state. We show that around the transition the Josephson supercurrent-phase relation changes from I(sc) approximately I(c)sin((phi) to I(sc) approximately I(c)sin((2phi). This implies that, around the transition, two minima in the junction free energy exist, one at phi=0 and one at phi=pi, whereas only one minimum exists at the 0 state (at phi=0) and at the pi state (at phi=pi). Theoretical calculations based on the quasiclassical theory are in good agreement with the observed behavior.
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Affiliation(s)
- J J A Baselmans
- Department of Applied Physics and Materials Science Center, University of Groningen, Nijenborg 4, 9747 AG Groningen, The Netherlands
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Smilde HJH, Blank DHA, Gerritsma GJ, Hilgenkamp H, Rogalla H. d-Wave-induced Josephson current counterflow in YBa2Cu3O7/Nb zigzag junctions. PHYSICAL REVIEW LETTERS 2002; 88:057004. [PMID: 11863770 DOI: 10.1103/physrevlett.88.057004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2001] [Indexed: 05/23/2023]
Abstract
Well-defined zigzag-shaped ramp-type Josephson junctions between YBa2Cu3O7 and Nb have been studied. The magnetic field dependencies of the critical currents provide evidence for d-wave--induced alternations in the direction of the Josephson current between neighboring sides of the zigzag structure. The arrays present controllable model systems to study the influences of pi facets in high-angle high- T(c) grain boundaries. From the characteristics, we estimate a possible imaginary s-wave admixture to the order parameter of the YBa2Cu3O7 to be below 1%.
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Affiliation(s)
- H J H Smilde
- Low Temperature Division, Department of Applied Physics and MESA+ Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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