Phase Diagram of Majorana Island

ORAL

Abstract

Scalable topological qubit proposals based on semiconductor-superconductor systems are built on Majorana islands hosting pairs of Majorana zero modes. Here, by systematically measuring the periodicity of Coulomb blockade oscillations of InSb/Al island, we reconstruct the ground state parity of the island over large ranges of magnetic field and plunger gate voltage (Vpg). The resulting phase diagram can be divided into three regimes compared with numerical simulations. For negative Vpg, sub-gap states are absent due to strong proximity effect, so the 2e to 1e-periodic transition happens at high B-fields, indicating the poisoning of the superconducting state. For positive Vpg, the 2e-1e transition happens instead at a constant but small B-field. The reason is un-proximitized states quickly disperse below the charging energy due to the orbital effect of the magnetic field. The two regimes are separated by an intermediate regime where the 2e-1e transition field varies smoothly with Vpg, which is the most promising for locating a robust topological phase according to simulations. In this regime, we observe correlated oscillating peak spacing and heights. This complete phase diagram of Majorana island can lead to a guideline to set up a topological qubit in more complicated devices.

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Presenters

  • Jie Shen

    • TU Delft
    • Delft University of Technology

Authors

  • Jie Shen

    • TU Delft
    • Delft University of Technology

  • Georg Wolfgang Winkler

    • Microsoft Station Q, University of California Santa Barbara

  • Francesco Borsoi

    • QuTech, Delft University of Technology
    • Delft University of Technology
    • TU Delft

  • Sebastian Heedt

    • Microsoft Quantum Lab Delft
    • Microsoft station Q Delft
    • Microsoft Corp Delft

  • Vukan Levajac

    • Delft University of Technology

  • Sasa Gazibegovic

    • Dept. of Physics, Technical University, Eindhoven, The Netherlands
    • Eindhoven University of Technology
    • Department of Applied Physics, Eindhoven University of Technology
    • Applied Physics, Eindhoven Univ. of Technology
    • TU Eindhoven

  • Roy Op het Veld

    • Dept. of Physics, Technical University, Eindhoven, The Netherlands
    • Eindhoven University of Technology
    • Applied Physics, Eindhoven Univ. of Technology
    • TU Eindhoven
    • Department of Applied Physics, Eindhoven University of Technology

  • Joon Sue Lee

    • California Nano-Systems Institute, Univ. of California, Santa Barbara, CA, USA
    • University of Tennessee Knoxville
    • Univ of California, Santa Barbara
    • Physics & Astronomy, Seoul National University
    • University of California Santa Barbara
    • California Nanosystems Institute, University of California Santa Barbara
    • University of California, Santa Barbara

  • Mihir Pendharkar

    • Dept. of Electrical Engineering, Univ. of California, Santa Barbara, CA, USA
    • IEE, UC Santa Barbara
    • University of California Santa Barbara
    • Univ of California, Santa Barbara
    • Electrical and Computer Engineering, University of California Santa Barbara
    • Electrical & Computer Engineering, University of California, Santa Barbara
    • University of California, Santa Barbara

  • connor dempsey

    • Dept. of Electrical Engineering, Univ. of California, Santa Barbara, CA, USA
    • IEE, UC Santa Barbara
    • University of California Santa Barbara

  • Chris Palmstrom

    • University of California Santa Barbara

  • Erik P.A.M. Bakkers

    • Eindhoven University of Technology

  • Bernard Van Heck

    • Microsoft Quantum Lab Delft, Delft University of Technology, 2600 GA Delft, The Netherlands
    • Microsoft
    • Quantum Lab Delft, Microsoft
    • Microsoft Quantum Lab Delft

  • Leo P. Kouwenhoven

    • Microsoft station Q Delft
    • Microsoft Quantum Lab Delft