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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