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Liu CH, Harrison DC, Patel S, Wilen CD, Rafferty O, Shearrow A, Ballard A, Iaia V, Ku J, Plourde BLT, McDermott R. Quasiparticle Poisoning of Superconducting Qubits from Resonant Absorption of Pair-Breaking Photons. PHYSICAL REVIEW LETTERS 2024; 132:017001. [PMID: 38242669 DOI: 10.1103/physrevlett.132.017001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 11/22/2023] [Accepted: 11/29/2023] [Indexed: 01/21/2024]
Abstract
The ideal superconductor provides a pristine environment for the delicate states of a quantum computer: because there is an energy gap to excitations, there are no spurious modes with which the qubits can interact, causing irreversible decay of the quantum state. As a practical matter, however, there exists a high density of excitations out of the superconducting ground state even at ultralow temperature; these are known as quasiparticles. Observed quasiparticle densities are of order 1 μm^{-3}, tens of orders of magnitude greater than the equilibrium density expected from theory. Nonequilibrium quasiparticles extract energy from the qubit mode and can induce dephasing. Here we show that a dominant mechanism for quasiparticle poisoning is direct absorption of high-energy photons at the qubit junction. We use a Josephson junction-based photon source to controllably dose qubit circuits with millimeter-wave radiation, and we use an interferometric quantum gate sequence to reconstruct the charge parity of the qubit. We find that the structure of the qubit itself acts as a resonant antenna for millimeter-wave radiation, providing an efficient path for photons to generate quasiparticles. A deep understanding of this physics will pave the way to realization of next-generation superconducting qubits that are robust against quasiparticle poisoning.
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Affiliation(s)
- C H Liu
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - D C Harrison
- Intelligence Community Postdoctoral Research Fellowship Program, Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S Patel
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - C D Wilen
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - O Rafferty
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A Shearrow
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A Ballard
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - V Iaia
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - J Ku
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - B L T Plourde
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - R McDermott
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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2
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Chatterjee AK, Takada S, Hayakawa H. Quantum Mpemba Effect in a Quantum Dot with Reservoirs. PHYSICAL REVIEW LETTERS 2023; 131:080402. [PMID: 37683159 DOI: 10.1103/physrevlett.131.080402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 07/17/2023] [Indexed: 09/10/2023]
Abstract
We demonstrate the quantum Mpemba effect in a quantum dot coupled to two reservoirs, described by the Anderson model. We show that the system temperatures starting from two different initial values (hot and cold) cross each other at finite time (and thereby reverse their identities; i.e., hot becomes cold and vice versa) to generate thermal quantum Mpemba effect. The slowest relaxation mode believed to play the dominating role in Mpemba effect in Markovian systems does not contribute to such anomalous relaxation in the present model. In this connection, our analytical result provides necessary condition for producing quantum Mpemba effect in the density matrix elements of the quantum dot, as a combined effect of the remaining relaxation modes.
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Affiliation(s)
- Amit Kumar Chatterjee
- Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawa Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Satoshi Takada
- Department of Mechanical Systems Engineering and Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Hisao Hayakawa
- Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawa Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
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Brange F, Prech K, Flindt C. Dynamic Cooper Pair Splitter. PHYSICAL REVIEW LETTERS 2021; 127:237701. [PMID: 34936782 DOI: 10.1103/physrevlett.127.237701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 11/08/2021] [Indexed: 06/14/2023]
Abstract
Cooper pair splitters are promising candidates for generating spin-entangled electrons. However, the splitting of Cooper pairs is a random and noisy process, which hinders further synchronized operations on the entangled electrons. To circumvent this problem, we here propose and analyze a dynamic Cooper pair splitter that produces a noiseless and regular flow of spin-entangled electrons. The Cooper pair splitter is based on a superconductor coupled to quantum dots, whose energy levels are tuned in and out of resonance to control the splitting process. We identify the optimal operating conditions for which exactly one Cooper pair is split per period of the external drive and the flow of entangled electrons becomes noiseless. To characterize the regularity of the Cooper pair splitter in the time domain, we analyze the g^{(2)} function of the output currents and the distribution of waiting times between split Cooper pairs. Our proposal is feasible using current technology, and it paves the way for dynamic quantum information processing with spin-entangled electrons.
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Affiliation(s)
- Fredrik Brange
- Department of Applied Physics, Aalto University, 00076 Aalto, Finland
| | - Kacper Prech
- Department of Applied Physics, Aalto University, 00076 Aalto, Finland
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Christian Flindt
- Department of Applied Physics, Aalto University, 00076 Aalto, Finland
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Tabatabaei SM, Sánchez D, Yeyati AL, Sánchez R. Andreev-Coulomb Drag in Coupled Quantum Dots. PHYSICAL REVIEW LETTERS 2020; 125:247701. [PMID: 33412025 DOI: 10.1103/physrevlett.125.247701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 10/29/2020] [Indexed: 06/12/2023]
Abstract
The Coulomb drag effect has been observed as a tiny current induced by both electron-hole asymmetry and interactions in normal coupled quantum dot devices. In the present work we show that the effect can be boosted by replacing one of the normal electrodes by a superconducting one. Moreover, we show that at low temperatures and for sufficiently strong coupling to the superconducting lead, the Coulomb drag is dominated by Andreev processes, is robust against details of the system parameters, and can be controlled with a single gate voltage. This mechanism can be distinguished from single-particle contributions by a sign inversion of the drag current.
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Affiliation(s)
- S Mojtaba Tabatabaei
- Department of Physics, Shahid Beheshti University, G. C. Evin, 1983963113 Tehran, Iran
| | - David Sánchez
- Institute for Cross-Disciplinary Physics and Complex Systems IFISC (UIB-CSIC), E-07122 Palma de Mallorca, Spain
| | - Alfredo Levy Yeyati
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC), and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Rafael Sánchez
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC), and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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Filippone M, Marguerite A, Le Hur K, Fève G, Mora C. Phase-Coherent Dynamics of Quantum Devices with Local Interactions. ENTROPY (BASEL, SWITZERLAND) 2020; 22:E847. [PMID: 33286618 PMCID: PMC7517448 DOI: 10.3390/e22080847] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/21/2020] [Accepted: 07/02/2020] [Indexed: 11/16/2022]
Abstract
This review illustrates how Local Fermi Liquid (LFL) theories describe the strongly correlated and coherent low-energy dynamics of quantum dot devices. This approach consists in an effective elastic scattering theory, accounting exactly for strong correlations. Here, we focus on the mesoscopic capacitor and recent experiments achieving a Coulomb-induced quantum state transfer. Extending to out-of-equilibrium regimes, aimed at triggered single electron emission, we illustrate how inelastic effects become crucial, requiring approaches beyond LFLs, shedding new light on past experimental data by showing clear interaction effects in the dynamics of mesoscopic capacitors.
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Affiliation(s)
- Michele Filippone
- Department of Quantum Matter Physics, University of Geneva 24 Quai Ernest-Ansermet, CH-1211 Geneva, Switzerland
| | - Arthur Marguerite
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel;
| | - Karyn Le Hur
- CPHT, CNRS, Institut Polytechnique de Paris, Route de Saclay, 91128 Palaiseau, France;
| | - Gwendal Fève
- Laboratoire de Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005 Paris, France;
| | - Christophe Mora
- Laboratoire Matériaux et Phénomènes Quantiques, CNRS, Université de Paris, F-75013 Paris, France;
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Arutyunov KY, Chernyaev SA, Karabassov T, Lvov DS, Stolyarov VS, Vasenko AS. Relaxation of nonequilibrium quasiparticles in mesoscopic size superconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:343001. [PMID: 30015330 DOI: 10.1088/1361-648x/aad3ea] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Rapid development of micro- and nanofabrication methods have provoked interest and enabled experimental studies of electronic properties of a vast class of (sub)micrometer-size solid state systems. Mesoscopic-size hybrid structures, containing superconducting elements, have become interesting objects for basic research studies and various applications, ranging from medical and astrophysical sensors to quantum computing. One of the most important aspects of physics, governing the behavior of such systems, is the finite concentration of nonequilibrium quasiparticles, present in a superconductor even well below the temperature of superconducting transition. Those nonequilibrium excitations might limit the performance of a variety of superconducting devices, like superconducting qubits, single-electron turnstiles and microrefrigerators. On the contrary, in some applications, like detectors of electromagnetic radiation, the nonequilibrium state is essential for their operation. It is therefore of vital importance to study the mechanisms of nonequilibrium quasiparticle relaxation in superconductors of mesoscopic dimensions, where the whole structure can be considered as an 'interface'. At early stages of research the problem was mostly studied in relatively massive systems and at high temperatures close to the critical temperature of a superconductor. We review the recent progress in studies of nonequilibrium quasiparticle relaxation in superconductors including the low temperature limit. We also discuss the open physical questions and perspectives of development in the field.
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Affiliation(s)
- K Yu Arutyunov
- National Research University Higher School of Economics, 101000 Moscow, Russia. P L Kapitza Institute for Physical Problems, Russian Academy of Sciences, 119334 Moscow, Russia
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Dutta B, Peltonen JT, Antonenko DS, Meschke M, Skvortsov MA, Kubala B, König J, Winkelmann CB, Courtois H, Pekola JP. Thermal Conductance of a Single-Electron Transistor. PHYSICAL REVIEW LETTERS 2017; 119:077701. [PMID: 28949696 DOI: 10.1103/physrevlett.119.077701] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Indexed: 06/07/2023]
Abstract
We report on combined measurements of heat and charge transport through a single-electron transistor. The device acts as a heat switch actuated by the voltage applied on the gate. The Wiedemann-Franz law for the ratio of heat and charge conductances is found to be systematically violated away from the charge degeneracy points. The observed deviation agrees well with the theoretical expectation. With a large temperature drop between the source and drain, the heat current away from degeneracy deviates from the standard quadratic dependence in the two temperatures.
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Affiliation(s)
- B Dutta
- Université Grenoble Alpes, CNRS, Institut Néel, 25 Avenue des Martyrs, 38042 Grenoble, France
| | - J T Peltonen
- Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076 Aalto, Finland
| | - D S Antonenko
- Skolkovo Institute of Science and Technology, Skolkovo, 143026 Moscow, Russia
- L. D. Landau Institute for Theoretical Physics, 142432 Chernogolovka, Russia
- Moscow Institute of Physics and Technology, Moscow, 141700, Russia
| | - M Meschke
- Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076 Aalto, Finland
| | - M A Skvortsov
- Skolkovo Institute of Science and Technology, Skolkovo, 143026 Moscow, Russia
- L. D. Landau Institute for Theoretical Physics, 142432 Chernogolovka, Russia
- Moscow Institute of Physics and Technology, Moscow, 141700, Russia
| | - B Kubala
- Institute for Complex Quantum Systems and IQST, University of Ulm, 89069 Ulm, Germany
| | - J König
- Theoretische Physik and CENIDE, Universität Duisburg-Essen, 47048 Duisburg, Germany
| | - C B Winkelmann
- Université Grenoble Alpes, CNRS, Institut Néel, 25 Avenue des Martyrs, 38042 Grenoble, France
| | - H Courtois
- Université Grenoble Alpes, CNRS, Institut Néel, 25 Avenue des Martyrs, 38042 Grenoble, France
| | - J P Pekola
- Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076 Aalto, Finland
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Basko DM. Landau-Zener-Stueckelberg Physics with a Singular Continuum of States. PHYSICAL REVIEW LETTERS 2017; 118:016805. [PMID: 28106431 DOI: 10.1103/physrevlett.118.016805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Indexed: 06/06/2023]
Abstract
This Letter addresses the dynamical quantum problem of a driven discrete energy level coupled to a semi-infinite continuum whose density of states has a square-root-type singularity, such as states of a free particle in one dimension or quasiparticle states in a BCS superconductor. The system dynamics is strongly affected by the quantum-mechanical repulsion between the discrete level and the singularity, which gives rise to a bound state, suppresses the decay into the continuum, and can produce Stueckelberg oscillations. This quantum coherence effect may limit the performance of mesoscopic superconducting devices, such as the quantum electron turnstile.
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Affiliation(s)
- D M Basko
- Laboratoire de Physique et Modélisation des Milieux Condensés, Université Grenoble Alpes and CNRS, F-38000 Grenoble, France
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Moskalets M. Fractionally Charged Zero-Energy Single-Particle Excitations in a Driven Fermi Sea. PHYSICAL REVIEW LETTERS 2016; 117:046801. [PMID: 27494490 DOI: 10.1103/physrevlett.117.046801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Indexed: 06/06/2023]
Abstract
A voltage pulse of a Lorentzian shape carrying half of the flux quantum excites out of a zero-temperature Fermi sea an electron in a mixed state, which looks like a quasiparticle with an effectively fractional charge e/2. A prominent feature of such an excitation is a narrow peak in the energy distribution function lying exactly at the Fermi energy μ. Another spectacular feature is that the distribution function has symmetric tails around μ, which results in a zero-energy excitation. This sounds improbable since at zero temperature all available states below μ are fully occupied. The resolution lies in the fact that such a voltage pulse also excites electron-hole pairs, which free some space below μ and thus allow a zero-energy quasiparticle to exist. I discuss also how to address separately electron-hole pairs and a fractionally charged zero-energy excitation in an experiment.
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Affiliation(s)
- Michael Moskalets
- Department of Metal and Semiconductor Physics, NTU "Kharkiv Polytechnic Institute", 61002 Kharkiv, Ukraine
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