Signatures of topological ground state degeneracy in Majorana islands

ORAL

Abstract

We consider a mesoscopic superconducting island hosting multiple pairs of Majorana zero-energy modes. The Majorana island consists of multiple p-wave wires connected together by a trivial (s-wave) superconducting backbone and is characterized by an overall charging energy Ec; the wires are coupled to normal-metal leads via tunnel junctions. Using a combination of analytical and numerical techniques we calculate the average charge on the island as well as non-local conductance matrix as a function of a p-wave pairing gap ΔP, charging energy Ec and dimensionless junction conductances gi. We find that the presence of a topological ground-state degeneracy in the island dramatically enhances charge fluctuations and leads to the suppression of Coulomb blockade effects. Specifically, in contrast with conventional (s-wave) mesoscopic superconducting islands, we find that Coulomb blockade effects are suppressed in Majorana islands regardless of the ratio Ec/ΔP or the magnitude of the conductances gi. We also discuss our findings in relation to the so-called topological Kondo effect.

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Presenters

  • Jukka Vayrynen

    • University of California, Santa Barbara
    • Microsoft Quantum, Microsoft Station Q, University of California Santa Barbara, Santa Barbara, CA 93106, USA

Authors

  • Jukka Vayrynen

    • University of California, Santa Barbara
    • Microsoft Quantum, Microsoft Station Q, University of California Santa Barbara, Santa Barbara, CA 93106, USA

  • Adrian Feiguin

    • Physics, Northeastern University
    • Northeastern University
    • Department of Physics, Northeastern University

  • Roman Lutchyn

    • Microsoft Quantum, Santa Barbara, CA, USA
    • Microsoft Corp
    • University of California, Santa Barbara
    • Microsoft Quantum, Microsoft Station Q, University of California Santa Barbara, Santa Barbara, CA 93106, USA
    • Station Q, Microsoft Research, Santa Barbara, California 93106-6105, USA