Critical Slowing Down in Circuit QED

ORAL

Abstract

We explore an intermediate non-linear driving regime in circuit QED for a 3D microwave cavity coupled to a transmon qubit, both experimentally and theoretically. In this regime, we measure the response of the cavity to a step function drive pulse, with the qubit initialized in either its ground or excited state, and observe critical slowing down, i.e. a very slow approach to the steady state, due to quantum bistability. We find that the system reaches the steady state in a time much longer than both the individual qubit and cavity lifetimes. We characterise the critical slowing down as a function of driving frequency and power and find good agreement with simulations. This regime may be exploited to improve circuit-QED based qubit readout.

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Presenters

  • Giovanna Tancredi

    • Physics, University of Oxford
    • Condensed Matter Physics, University of Oxford
    • Clarendon Laboratory, University of Oxford

Authors

  • Giovanna Tancredi

    • Physics, University of Oxford
    • Condensed Matter Physics, University of Oxford
    • Clarendon Laboratory, University of Oxford

  • Paul Brookes

    • Physics, University College London

  • Themis Mavrogordatos

    • Physics, University College London

  • Andrew Patterson

    • Physics, University of Oxford
    • Condensed Matter Physics, University of Oxford
    • Clarendon Laboratory, University of Oxford

  • Joseph Rahamim

    • Physics, University of Oxford
    • Condensed Matter Physics, University of Oxford
    • Clarendon Laboratory, University of Oxford

  • Eran Ginossar

    • Physics, University of Surrey
    • Advanced Technology Institute and Department of Physics, University of Surrey

  • Marzena Szymanska

    • Physics, University College London

  • Peter Leek

    • Physics, University of Oxford
    • Clarendon Laboratory, Department of Physics, University of Oxford
    • Condensed Matter Physics, University of Oxford
    • Clarendon Laboratory, University of Oxford