Observation of conductance doubling in an Andreev quantum point contact

ORAL

Abstract

One route to study the non-Abelian nature of excitations in topological superconductors is to realise gateable two dimensional (2D) semiconducting systems, with spin-orbit coupling in proximity to an s-wave superconductor. Previous work on coupling 2D electron gases (2DEG) with superconductors has been hindered by a non-ideal interface and unstable gateability. We report measurements on a gateable 2DEG coupled to superconductors through a pristine interface, and use aluminum grown in situ epitaxially on an InGaAs/InAs electron gas. We demonstrate quantization in units of $4e^2/h$ in a quantum point contact (QPC) in such hybrid systems. Operating the QPC as a tunnel probe, we observe a hard superconducting gap, overcoming the soft-gap problem in 2D superconductor/semiconductor systems. Our work paves way for a new and highly scalable system in which to pursue topological quantum information processing.

*Research supported by Microsoft Project Q and the Danish National Research Foundation

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Authors

  • M Kjaergaard

    • Center for Quantum Devices & Station Q Copenhagen

  • F Nichele

    • Center for Quantum Devices & Station Q Copenhagen

  • H Suominen

    • Center for Quantum Devices & Station Q Copenhagen

  • M Nowak

    • Kavli Institute for Nanoscience, TU Delft

  • Michael Wimmer

    • Kavli Institute for Nanoscience, TU Delft
    • TU Delft, Netherlands

  • A Akhmerov

    • Kavli Institute for Nanoscience, TU Delft

  • Joshua Folk

    • University of British Columbia
    • Department of Physics and Astronomy, Unversity of British Columbia
    • Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T1Z1, Canada

  • K Flensberg

    • Center for Quantum Devices & Station Q Copenhagen

  • J Shabani

    • Physics Department, City College of New York
    • Physics Department, CCNY

  • Chris Palmstrom

    • California NanoSystems Institute, University of California Santa Barbara
    • Materials Department, Department of Electrical and Computer Engineering, University of California at Santa Barbara
    • Materials Department, University of California-Santa Barbara, Santa Barbara, California 93106, USA
    • Electrical and Computer Engineering Department & Materials Department, University of California Santa Barbara
    • Materials Department and Department of Electrical and Computer Engineering, Univ of California, Santa Barbara
    • Materials Department, University of California, Santa Barbara

  • Charles M. Marcus

    • Center for Quantum Devices & Station Q Copenhagen
    • Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark