The Cooper-Quartet Box

ORAL

Abstract

We present the experimental implementation of a protected qubit candidate: the Cooper-Quartet Box (CQB). A superconducting island is connected to ground through a tunnelling element (known as the KITE) that only allows pairs of Cooper pairs to tunnel. We observe a doubling of the eigenspectrum into two parity sectors, a hallmark of quartet tunnelling. We analyze the decay mechanisms of the ground state doublet as a function of flux and charge and discuss the prospects of the CQB as a protected qubit or charge detector.

*ERC 851740, ANR-22-PETQ-0003.

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Presenters

  • Erwan Roverch

    • École Normale Supérieure – PSL

Authors

  • Erwan Roverch

    • École Normale Supérieure – PSL

  • Alvise Borgognoni

    • Mines ParisTech

  • Kyrylo Gerashchenko

    • Laboratoire Kastler-Brossel

  • Marius Villiers

    • École normal supérieure Paris-Saclay

  • Clarke Smith

    • Google LLC

  • Alexandru Petrescu

    • INRIA
    • Mines Paris - INRIA

  • Philippe Campagne-Ibarcq

    • INRIA
    • Inria

  • Benoit Doucot

    • LPTHE, Sorbonne Université

  • Zaki Leghtas

    • Mines Paris
    • LPENS, Ecole Normale Supérieure-PSL