Majorana π-junctions in full-shell nanowire SQUIDs

ORAL

Abstract

Recent studies of InAs nanowires covered by full-shell Al superconductor showed signatures of Majorana zero modes (MZMs) around one applied axial-flux quantum [1]. Here, we study such wires in dc-SQUID geometry with a naturally-formed normal quantum dots in the Josephson junctions. In the trivial regime around zero axial-flux we find 0-π transition as the occupancy of a quantum dot is changed; the transition vanishes at one axial-flux quantum. In addition, we find that the critical currents of the Josephson junctions increase in the topological regime. Tunneling spectroscopy of a junction in the π-state reveals a discrete zero-energy state at one applied axial-flux quantum. Our observations are consistent with the theoretical models of MZMs coupling through a normal quantum dot [2,3].

[1] S. Vaitiekenas et al. arxiv:1809.05513
[2] C. Schrade and L. Fu arxiv:1809.06370
[3] J. Schulenborg and K. Flensberg. arxiv:1910.04106

*Research is supported by Microsoft Project Q and the Danish National Research Foundation. CMM acknowledges support from the Villum Foundation.

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Presenters

  • Davydas Razmadze

    • Niels Bohr Institute, University of Copenhagen

Authors

  • Davydas Razmadze

    • Niels Bohr Institute, University of Copenhagen

  • Eoin C O'Farrell

    • Niels Bohr Institute, University of Copenhagen

  • Peter Krogstrup

    • Niels Bohr Institute, University of Copenhagen
    • University of Copenhagen
    • Center for Quantum Devices and Microsoft Quantum Lab--Copenhagen, Niels Bohr Institute, University of Copenhagen
    • Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen

  • Charles Marcus

    • Center for Quantum Devices and Microsoft Quantum Lab Copenhagen, Niels Bohr Institute, University of Copenhagen
    • Microsoft Quantum Lab Copenhagen and Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
    • Univ of Copenhagen
    • Center for Quantum Devices and Microsoft Quantum Lab - Copenhagen, University of Copenhagen
    • Center for Quantum Devices, Microsoft Quantum Lab – Copenhagen and Niels Bohr Institute, University of Copenhagen
    • Microsoft Corp
    • Niels Bohr Institute, University of Copenhagen