Bifluxon: Fluxon-Parity-Protected Superconducting Qubit

ORAL

Abstract

We have developed and characterized a symmetry-protected superconducting qubit that offers simultaneous exponential suppression of energy decay from both the charge and flux noise, and dephasing from flux noise [1]. The qubit is implemented as a superconducting loop formed by a Cooper-pair box (CPB) and a superinductor. Provided the offset charge on the CPB island is an odd number of electrons, the qubit potential corresponds to that of a cos (φ/2) Josephson element, preserving the parity of fluxons in the loop via Aharonov-Casher interference. Importantly, the protection can be turned on and off by controlling the CPB charge. In the protected state, the logical-state wavefunctions reside in disjoint regions of phase space, thereby ensuring protection against energy decay. By turning the protection on, we observed a ten-fold increase of the decay time, up to 100 μs. We will discuss strategies for mitigation of the charge noise effects by designing small arrays of cos (φ/2) elements.

1. K. Kalashnikov et al., Bifluxon: Fluxon-Parity-Protected Superconducting Qubit, arXiv:1910.03769.

*Funding Acknowledgements: NSF DMR-1708954, DMR-1838979, ECCS-1608448, DUE-1723511, ARO W911NF-17-C-0024, 2019 Google Faculty Research Award, NSERC and the Canada First Research Excellence Fund.

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Presenters

  • Konstantin Kalashnikov

    • Rutgers University, New Brunswick

Authors

  • Konstantin Kalashnikov

    • Rutgers University, New Brunswick

  • Wen Ting Hsieh

    • Engineering Department, University of Massachusetts Boston, Boston, MA

  • Wenyuan Zhang

    • Rutgers University, New Brunswick

  • Wen-Sen Lu

    • Rutgers University, New Brunswick

  • Plamen Kamenov

    • Rutgers University, New Brunswick

  • Agustin Di Paolo

    • Institut quantique and Departement de Physique, Universite de Sherbrooke
    • Universite de Sherbrooke
    • Département de Physique, Université de Sherbrooke
    • Institut quantique & Département de Physique, Université de Sherbrooke
    • Institut Quantique and Departement de Physique, Universite de Sherbrooke, Sherbrooke, Canada
    • Institut quantique and Département de Physique, Universite de Sherbrooke

  • Alexandre Blais

    • Universite de Sherbrooke
    • Institut quantique and Departement de Physique, Universite de Sherbrooke
    • Institut Quantique, Universite de Sherbrooke
    • Département de Physique, Université de Sherbrooke
    • Institut quantique & Département de Physique, Université de Sherbrooke
    • Institut Quantique and Departement de Physique, Universite de Sherbrooke, Sherbrooke, Canada
    • Institut quantique and Département de Physique, Universite de Sherbrooke

  • Michael Gershenson

    • Rutgers University, New Brunswick

  • Matthew T Bell

    • University of Massachusetts, Boston
    • Engineering Department, University of Massachusetts Boston, Boston, MA