Even to Odd Fermion Parity Transition in Majorana Islands based on Al-InSb Hybrid System

ORAL

Abstract

Different topological qubit schemes, based on one-dimensional nanowires with proximity-induced superconductivity, have been proposed. Most of them consist of multiple superconducting islands in the Coulomb blockade regime, each hosting pairs of Majorana zero modes (MZMs). We build such Majorana islands in InSb nanowires with epitaxial Al shells. The measurement of Coulomb diamonds reveals 2e periodicity with respect to the gate voltage, originating from the even fermion parity being protected by a hard superconducting gap. When a magnetic field is applied parallel to the nanowire, the 2e periodicity gradually changes to 1e-periodic oscillations with alternating regions of even and odd fermion parity. This behavior is related to the appearance of low-energy states, signalling either the appearance of MZMs in the topological regime or the presence of non-topological Andreev bound states. By sweeping across large ranges of plunger gate and tunneling gate voltages, we found that some features are very sensitive to the gate settings, and thus easily construed in terms of localized Andreev bound states. In other cases, the 1e oscillations are more robust and accompanied by an excitation gap in finite bias measurements, which could be interpreted as due to the presence of MZMs.

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Presenters

  • Jie Shen

    Delft Univ of Tech

Authors

  • Jie Shen

    Delft Univ of Tech

  • Sebastian Heedt

    Delft Univ of Tech

  • Francesco Borsoi

    Delft Univ of Tech, QuTech, Delft Univ. of Technology

  • Bernard Van Heck

    Station Q, Microsoft Research

  • Sasa Gazibegovic

    Department of Applied Physics, Eindhoven University of Technology, Eindhoven Univ of Tech, Eindhoven University of Technology

  • Diana Car

    Eindhoven Univ of Tech, Department of Applied Physics, Eindhoven University of Technology, Eindhoven University of Technology

  • Roy L. M. Op het Veld

    Department of Applied Physics, Eindhoven University of Technology

  • Daniël Bouman

    Delft Univ of Tech

  • John Logan

    University of California Santa Barbara, Materials Department, University of California, University of California-Santa Barbara, University of California - Santa Barbara

  • Chris Palmstrom

    University of California Santa Barbara, Materials Department, California NanoSystems Institute, Electrical and Computer Engineering, University of California, University of California-Santa Barbara, California Nanosystems Institute, Dept. of Electrical and Computer Engineering, and Dept. of Materials, Univ of California - Santa Barbara, University of California - Santa Barbara, Electronics & Computer Enginneering, University of California Santa Barbara, Materials Department, University of California, Santa Barbara, Materials, University of California Santa Barbara, Univ of California - Santa Barbara

  • Attila Geresdi

    QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft Univ of Tech, QuTech and Kavli Institute of NanoScience, Delft University of Technology

  • Erik P. A. M. Bakkers

    Department of Applied Physics, Eindhoven University of Technology, Eindhoven University of Technology

  • Leo Kouwenhoven

    Microsoft Station-Q Delft, Delft University of Technology, Delft Univ of Tech, Qutech and Kavli Institute of Nanoscience and Microsoft Station Q Delft, Delft University of Technology, QuTech, Kavli Institute of Nanoscience, Station Q at Delft University of Technology, Delft University of Technology, Microsoft Station-Q at Delft University of Technology, Delft Univ. of Technology, Microsoft Station Q, Station Q Delft, Microsoft, Microsoft Station Q