1
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Haxell DZ, Coraiola M, Sabonis D, Hinderling M, Ten Kate SC, Cheah E, Krizek F, Schott R, Wegscheider W, Belzig W, Cuevas JC, Nichele F. Microwave-induced conductance replicas in hybrid Josephson junctions without Floquet-Andreev states. Nat Commun 2023; 14:6798. [PMID: 37884490 PMCID: PMC10603169 DOI: 10.1038/s41467-023-42357-5] [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: 06/12/2023] [Accepted: 10/09/2023] [Indexed: 10/28/2023] Open
Abstract
Light-matter coupling allows control and engineering of complex quantum states. Here we investigate a hybrid superconducting-semiconducting Josephson junction subject to microwave irradiation by means of tunnelling spectroscopy of the Andreev bound state spectrum and measurements of the current-phase relation. For increasing microwave power, discrete levels in the tunnelling conductance develop into a series of equally spaced replicas, while the current-phase relation changes amplitude and skewness, and develops dips. Quantitative analysis of our results indicates that conductance replicas originate from photon assisted tunnelling of quasiparticles into Andreev bound states through the tunnelling barrier. Despite strong qualitative similarities with proposed signatures of Floquet-Andreev states, our study rules out this scenario. The distortion of the current-phase relation is explained by the interaction of Andreev bound states with microwave photons, including a non-equilibrium Andreev bound state occupation. The techniques outlined here establish a baseline to study light-matter coupling in hybrid nanostructures and distinguish photon assisted tunnelling from Floquet-Andreev states in mesoscopic devices.
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Affiliation(s)
| | - Marco Coraiola
- IBM Research Europe-Zurich, 8803, Rüschlikon, Switzerland
| | | | | | | | - Erik Cheah
- Laboratory for Solid State Physics, ETH Zürich, 8093, Zürich, Switzerland
| | - Filip Krizek
- IBM Research Europe-Zurich, 8803, Rüschlikon, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, 8093, Zürich, Switzerland
| | - Rüdiger Schott
- Laboratory for Solid State Physics, ETH Zürich, 8093, Zürich, Switzerland
| | - Werner Wegscheider
- Laboratory for Solid State Physics, ETH Zürich, 8093, Zürich, Switzerland
| | - Wolfgang Belzig
- Fachbereich Physik, Universität Konstanz, D-78457, Konstanz, Germany
| | - Juan Carlos Cuevas
- Fachbereich Physik, Universität Konstanz, D-78457, Konstanz, Germany
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049, Madrid, Spain
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2
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Haxell D, Coraiola M, Sabonis D, Hinderling M, ten Kate SC, Cheah E, Krizek F, Schott R, Wegscheider W, Nichele F. Zeeman- and Orbital-Driven Phase Shifts in Planar Josephson Junctions. ACS NANO 2023; 17:18139-18147. [PMID: 37694539 PMCID: PMC10540266 DOI: 10.1021/acsnano.3c04957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/25/2023] [Indexed: 09/12/2023]
Abstract
We perform supercurrent and tunneling spectroscopy measurements on gate-tunable InAs/Al Josephson junctions (JJs) in an in-plane magnetic field and report on phase shifts in the current-phase relation measured with respect to an absolute phase reference. The impact of orbital effects is investigated by studying multiple devices with different superconducting lead sizes. At low fields, we observe gate-dependent phase shifts of up to φ0 = 0.5π, which are consistent with a Zeeman field coupling to highly transmissive Andreev bound states via Rashba spin-orbit interaction. A distinct phase shift emerges at larger fields, concomitant with a switching current minimum and the closing and reopening of the superconducting gap. These signatures of an induced phase transition, which might resemble a topological transition, scale with the superconducting lead size, demonstrating the crucial role of orbital effects. Our results elucidate the interplay of Zeeman, spin-orbit, and orbital effects in InAs/Al JJs, giving improved understanding of phase transitions in hybrid JJs and their applications in quantum computing and superconducting electronics.
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Affiliation(s)
| | - Marco Coraiola
- IBM
Research Europe−Zurich, 8803 Rüschlikon, Switzerland
| | | | | | | | - Erik Cheah
- Laboratory
for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Filip Krizek
- IBM
Research Europe−Zurich, 8803 Rüschlikon, Switzerland
- Laboratory
for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
- Institute
of Physics, Czech Academy of Sciences, 162 00 Prague, Czech Republic
| | - Rüdiger Schott
- Laboratory
for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Werner Wegscheider
- Laboratory
for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
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3
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Lee M, López R, Xu HQ, Platero G. Proposal for Detection of the 0^{'} and π^{'} Phases in Quantum-Dot Josephson Junctions. PHYSICAL REVIEW LETTERS 2022; 129:207701. [PMID: 36462010 DOI: 10.1103/physrevlett.129.207701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 10/03/2022] [Indexed: 06/17/2023]
Abstract
The competition between the Kondo correlation and superconductivity in quantum-dot Josephson junctions (QDJJs) has been known to drive a quantum phase transition between 0 and π junctions. Theoretical studies so far have predicted that under strong Coulomb correlations the 0-π transition should go through intermediate states, 0^{'} and π^{'} phases. By combining a nonperturbative numerical method and the resistively shunted junction model, we investigated the magnetic-field-driven phase transition of the QDJJs in the Kondo regime and found that the low-field magnetotransport exhibits a unique feature which can be used to distinguish the intermediate phases. In particular, the magnetic-field driven π^{'}-π transition is found to lead to the enhancement of the supercurrent which is strongly related to the Kondo effect.
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Affiliation(s)
- Minchul Lee
- Department of Applied Physics and Institute of Natural Science, College of Applied Science, Kyung Hee University, Yongin 17104, Korea
| | - Rosa López
- Institut de Física Interdisciplinària i de Sistemes Complexos IFISC (CSIC-UIB), E-07122 Palma de Mallorca, Spain
| | - H Q Xu
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Gloria Platero
- Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), 28049 Cantoblanco, Madrid, Spain
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4
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Contamin LC, Jarjat L, Legrand W, Cottet A, Kontos T, Delbecq MR. Zero energy states clustering in an elemental nanowire coupled to a superconductor. Nat Commun 2022; 13:6188. [PMID: 36261661 PMCID: PMC9581951 DOI: 10.1038/s41467-022-33960-z] [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: 04/07/2022] [Accepted: 10/05/2022] [Indexed: 11/13/2022] Open
Abstract
Nanoelectronic hybrid devices combining superconductors and a one-dimensional nanowire are promising platforms to realize topological superconductivity and its resulting exotic excitations. The bulk of experimental studies in this context are transport measurements where conductance peaks allow to perform a spectroscopy of the low lying electronic states and potentially to identify signatures of the aforementioned excitations. The complexity of the experimental landscape calls for a benchmark in an elemental situation. The present work tackles such a task using an ultra-clean carbon nanotube circuit. Specifically, we show that the combination of magnetic field, weak disorder and superconductivity can lead to states clustering at low energy, as predicted by the random matrix theory predictions. Such a phenomenology is very general and should apply to most platforms trying to realize topological superconductivity in 1D systems, thus calling for alternative probes to reveal it. Topological superconductivity (TSC) is predicted to exist in nanowires with strong spin-orbit coupling (SOC) when they are in proximity to superconductors, with a key signature being zero-energy states in conductance measurements. Here, using weak-SOC carbon nanotubes as the nanowires, the authors show that similar looking zero-energy states can appear even in nanowires which cannot, in principle, host TSC.
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Affiliation(s)
- Lauriane C Contamin
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - Lucas Jarjat
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - William Legrand
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - Audrey Cottet
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - Takis Kontos
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - Matthieu R Delbecq
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France.
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5
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Zhang P, Wu H, Chen J, Khan SA, Krogstrup P, Pekker D, Frolov SM. Signatures of Andreev Blockade in a Double Quantum Dot Coupled to a Superconductor. PHYSICAL REVIEW LETTERS 2022; 128:046801. [PMID: 35148137 DOI: 10.1103/physrevlett.128.046801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 10/01/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
We investigate an electron transport blockade regime in which a spin triplet localized in the path of current is forbidden from entering a spin-singlet superconductor. To stabilize the triplet, a double quantum dot is created electrostatically near a superconducting Al lead in an InAs nanowire. The quantum dot closest to the normal lead exhibits Coulomb diamonds, and the dot closest to the superconducting lead exhibits Andreev bound states and an induced gap. The experimental observations compare favorably to a theoretical model of Andreev blockade, named so because the triplet double dot configuration suppresses Andreev reflections. Observed leakage currents can be accounted for by finite temperature. We observe the predicted quadruple level degeneracy points of high current and a periodic conductance pattern controlled by the occupation of the normal dot. Even-odd transport asymmetry is lifted with increased temperature and magnetic field. This blockade phenomenon can be used to study spin structure of superconductors. It may also find utility in quantum computing devices that use Andreev or Majorana states.
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Affiliation(s)
- Po Zhang
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Hao Wu
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Jun Chen
- Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Sabbir A Khan
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Peter Krogstrup
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - David Pekker
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Sergey M Frolov
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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6
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Ricco LS, Sanches JE, Marques Y, de Souza M, Figueira MS, Shelykh IA, Seridonio AC. Topological isoconductance signatures in Majorana nanowires. Sci Rep 2021; 11:17310. [PMID: 34453069 PMCID: PMC8397770 DOI: 10.1038/s41598-021-96415-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 08/04/2021] [Indexed: 11/23/2022] Open
Abstract
We consider transport properties of a hybrid device composed by a quantum dot placed between normal and superconducting reservoirs, and coupled to a Majorana nanowire: a topological superconducting segment hosting Majorana bound states (MBSs) at the opposite ends. It is demonstrated that if highly nonlocal and nonoverlapping MBSs are formed in the system, the zero-bias Andreev conductance through the dot exhibits characteristic isoconductance profiles with the shape depending on the spin asymmetry of the coupling between the dot and the topological superconductor. Otherwise, for overlapping MBSs with less degree of nonlocality, the conductance is insensitive to the spin polarization and the isoconductance signatures disappear. This allows to propose an alternative experimental protocol for probing the nonlocality of the MBSs in Majorana nanowires.
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Affiliation(s)
- L S Ricco
- Science Institute, University of Iceland, Dunhagi-3, 107, Reykjavik, Iceland.
| | - J E Sanches
- School of Engineering, Department of Physics and Chemistry, São Paulo State University (Unesp), 15385-000, Ilha Solteira, SP, Brazil
| | - Y Marques
- Department of Physics, ITMO University, 197101, St. Petersburg, Russia
| | - M de Souza
- Department of Physics, São Paulo State University (Unesp), IGCE, 13506-970, Rio Claro, SP, Brazil
| | - M S Figueira
- Instituto de Física, Universidade Federal Fluminense, 24210-340, Niterói, Rio de Janeiro, Brazil
| | - I A Shelykh
- Science Institute, University of Iceland, Dunhagi-3, 107, Reykjavik, Iceland
- Department of Physics, ITMO University, 197101, St. Petersburg, Russia
| | - A C Seridonio
- School of Engineering, Department of Physics and Chemistry, São Paulo State University (Unesp), 15385-000, Ilha Solteira, SP, Brazil
- Department of Physics, São Paulo State University (Unesp), IGCE, 13506-970, Rio Claro, SP, Brazil
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7
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Sadek D, Dhungana DS, Coratger R, Durand C, Proietti A, Gravelier Q, Reig B, Daran E, Fazzini PF, Cristiano F, Arnoult A, Plissard SR. Integration of the Rhombohedral BiSb(0001) Topological Insulator on a Cubic GaAs(001) Substrate. ACS APPLIED MATERIALS & INTERFACES 2021; 13:36492-36498. [PMID: 34296846 DOI: 10.1021/acsami.1c08477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Bismuth-antimony alloy (Bi1 - xSbx) is the first reported 3D topological insulator (TI). Among many TIs reported to date, it remains the most promising for spintronic applications thanks to its large conductivity, its colossal spin Hall angle, and the possibility to build low-current spin-orbit-torque magnetoresistive random access memories. Nevertheless, the 2D integration of TIs on industrial standards is lacking. In this work, we report the integration of high-quality rhombohedral BiSb(0001) topological insulators on a cubic GaAs(001) substrate. We demonstrate a clear epitaxial relationship at the interface, a fully relaxed TI layer, and the growth of a rhombohedral matrix on top of the cubic substrate. The antimony composition of the Bi1 - xSbx layer is perfectly controlled and covers almost the whole TI window. For optimized growth conditions, the sample generates a semiconductor band structure at room temperature in the bulk and exhibits metallic surface states at 77 K.
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Affiliation(s)
- Dima Sadek
- LAAS-CNRS, Université de Toulouse, Toulouse F-31400, France
| | | | - Roland Coratger
- SINANO Group, CEMES-CNRS and Université Paul Sabatier, 29 rue J. Marvig, Toulouse 31055, France
| | - Corentin Durand
- LAAS-CNRS, Université de Toulouse, Toulouse F-31400, France
- SINANO Group, CEMES-CNRS and Université Paul Sabatier, 29 rue J. Marvig, Toulouse 31055, France
| | - Arnaud Proietti
- Centre De Microcaractérisation Raimond Castaing, Espace Clément Ader, 3 Rue Caroline Aigle, Toulouse F-31400, France
| | | | - Benjamin Reig
- LAAS-CNRS, Université de Toulouse, Toulouse F-31400, France
| | | | - Pier Francesco Fazzini
- Laboratoire de Physique et Chimie des Nano-objets, Institut National des Sciences Appliquées, 135 Avenue de Rangueil, Toulouse, Cedex 4 F-31077, France
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8
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Valentini M, Peñaranda F, Hofmann A, Brauns M, Hauschild R, Krogstrup P, San-Jose P, Prada E, Aguado R, Katsaros G. Nontopological zero-bias peaks in full-shell nanowires induced by flux-tunable Andreev states. Science 2021; 373:82-88. [PMID: 34210881 DOI: 10.1126/science.abf1513] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 05/21/2021] [Indexed: 11/02/2022]
Abstract
A semiconducting nanowire fully wrapped by a superconducting shell has been proposed as a platform for obtaining Majorana modes at small magnetic fields. In this study, we demonstrate that the appearance of subgap states in such structures is actually governed by the junction region in tunneling spectroscopy measurements and not the full-shell nanowire itself. Short tunneling regions never show subgap states, whereas longer junctions always do. This can be understood in terms of quantum dots forming in the junction and hosting Andreev levels in the Yu-Shiba-Rusinov regime. The intricate magnetic field dependence of the Andreev levels, through both the Zeeman and Little-Parks effects, may result in robust zero-bias peaks-features that could be easily misinterpreted as originating from Majorana zero modes but are unrelated to topological superconductivity.
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Affiliation(s)
- Marco Valentini
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria.
| | - Fernando Peñaranda
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
| | - Andrea Hofmann
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Matthias Brauns
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Robert Hauschild
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Peter Krogstrup
- Microsoft Quantum Materials Lab and Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Kanalvej 7, 2800 Kongens Lyngby, Denmark
| | - Pablo San-Jose
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
| | - Elsa Prada
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.,Departamento de Física de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Ramón Aguado
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.
| | - Georgios Katsaros
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria.
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9
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Pendharkar M, Zhang B, Wu H, Zarassi A, Zhang P, Dempsey CP, Lee JS, Harrington SD, Badawy G, Gazibegovic S, Op Het Veld RLM, Rossi M, Jung J, Chen AH, Verheijen MA, Hocevar M, Bakkers EPAM, Palmstrøm CJ, Frolov SM. Parity-preserving and magnetic field-resilient superconductivity in InSb nanowires with Sn shells. Science 2021; 372:508-511. [PMID: 33858990 DOI: 10.1126/science.aba5211] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/13/2021] [Indexed: 11/02/2022]
Abstract
Improving materials used to make qubits is crucial to further progress in quantum information processing. Of particular interest are semiconductor-superconductor heterostructures that are expected to form the basis of topological quantum computing. We grew semiconductor indium antimonide nanowires that were coated with shells of tin of uniform thickness. No interdiffusion was observed at the interface between Sn and InSb. Tunnel junctions were prepared by in situ shadowing. Despite the lack of lattice matching between Sn and InSb, a 15-nanometer-thick shell of tin was found to induce a hard superconducting gap, with superconductivity persisting in magnetic field up to 4 teslas. A small island of Sn-InSb exhibits the two-electron charging effect. These findings suggest a less restrictive approach to fabricating superconducting and topological quantum circuits.
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Affiliation(s)
- M Pendharkar
- Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA
| | - B Zhang
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - H Wu
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - A Zarassi
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - P Zhang
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - C P Dempsey
- Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA
| | - J S Lee
- California NanoSystems Institute, University of California, Santa Barbara, CA 93106, USA
| | - S D Harrington
- Materials Department, University of California, Santa Barbara, CA 93106, USA
| | - G Badawy
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - S Gazibegovic
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | | | - M Rossi
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - J Jung
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - A-H Chen
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - M A Verheijen
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - M Hocevar
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - E P A M Bakkers
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - C J Palmstrøm
- Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA.,California NanoSystems Institute, University of California, Santa Barbara, CA 93106, USA.,Materials Department, University of California, Santa Barbara, CA 93106, USA
| | - S M Frolov
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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10
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Large spatial extension of the zero-energy Yu-Shiba-Rusinov state in a magnetic field. Nat Commun 2020; 11:1834. [PMID: 32286260 PMCID: PMC7156378 DOI: 10.1038/s41467-020-15322-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 03/03/2020] [Indexed: 11/30/2022] Open
Abstract
Various promising qubit concepts have been put forward recently based on engineered superconductor subgap states like Andreev bound states, Majorana zero modes or the Yu-Shiba-Rusinov (Shiba) states. The coupling of these subgap states via a superconductor strongly depends on their spatial extension and is an essential next step for future quantum technologies. Here we investigate the spatial extension of a Shiba state in a semiconductor quantum dot coupled to a superconductor. With detailed transport measurements and numerical renormalization group calculations we find a remarkable more than 50 nm extension of the zero energy Shiba state, much larger than the one observed in very recent scanning tunneling microscopy measurements. Moreover, we demonstrate that its spatial extension increases substantially in a magnetic field. Local magnetic moments coupled to superconductors can form subgap Yu-Shiba-Rusinov states. Here the authors show that Shiba states made with an InAs nanowire quantum dot have large spatial extent, which is beneficial for making Shiba chains that are predicted to host Majorana zero modes.
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11
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Desjardins MM, Contamin LC, Delbecq MR, Dartiailh MC, Bruhat LE, Cubaynes T, Viennot JJ, Mallet F, Rohart S, Thiaville A, Cottet A, Kontos T. Synthetic spin-orbit interaction for Majorana devices. NATURE MATERIALS 2019; 18:1060-1064. [PMID: 31427741 DOI: 10.1038/s41563-019-0457-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 07/15/2019] [Indexed: 06/10/2023]
Abstract
The interplay of superconductivity with non-trivial spin textures is promising for the engineering of non-Abelian Majorana quasiparticles. Spin-orbit coupling is crucial for the topological protection of Majorana modes as it forbids other trivial excitations at low energy but is typically intrinsic to the material1-7. Here, we show that coupling to a magnetic texture can induce both a strong spin-orbit coupling of 1.1 meV and a Zeeman effect in a carbon nanotube. Both of these features are revealed through oscillations of superconductivity-induced subgap states under a change in the magnetic texture. Furthermore, we find a robust zero-energy state-the hallmark of devices hosting localized Majorana modes-at zero magnetic field. Our findings are generalizable to any low-dimensional conductor, and future work could include microwave spectroscopy and braiding operations, which are at the heart of modern schemes for topological quantum computation.
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Affiliation(s)
- M M Desjardins
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - L C Contamin
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - M R Delbecq
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - M C Dartiailh
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - L E Bruhat
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - T Cubaynes
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - J J Viennot
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, CNRS, Grenoble, France
| | - F Mallet
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - S Rohart
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS UMR 8502, Orsay, France
| | - A Thiaville
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS UMR 8502, Orsay, France
| | - A Cottet
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - T Kontos
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
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Estrada Saldaña JC, Vekris A, Steffensen G, Žitko R, Krogstrup P, Paaske J, Grove-Rasmussen K, Nygård J. Supercurrent in a Double Quantum Dot. PHYSICAL REVIEW LETTERS 2018; 121:257701. [PMID: 30608792 DOI: 10.1103/physrevlett.121.257701] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Indexed: 06/09/2023]
Abstract
We demonstrate the Josephson effect in a serial double quantum dot defined in a nanowire with epitaxial superconducting leads. The supercurrent stability diagram adopts a honeycomb pattern. We observe sharp discontinuities in the magnitude of the critical current, I_{c}, as a function of dot occupation, related to doublet to singlet ground state transitions. Detuning of the energy levels offers a tuning knob for I_{c}, which attains a maximum at zero detuning. The consistency between experiment and theory indicates that our device is a faithful realization of the two-impurity Anderson model.
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Affiliation(s)
- J C Estrada Saldaña
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - A Vekris
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - G Steffensen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - R Žitko
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
| | - P Krogstrup
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
- Microsoft Quantum Materials Lab Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - J Paaske
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - K Grove-Rasmussen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - J Nygård
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
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