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Isolating a qubit from amplifier backaction by coordinated switching

ORAL

Abstract

We demonstrate a cQED qubit measurement scheme in which the qubit is isolated from amplifier backaction without ferrite circulators. We swap a readout signal from the qubit cavity to an ancillary cavity by temporarily coupling them. The state of the ancillary cavity is then amplified by parametrically pumping past bifurcation into one of two large amplitude states that are correlated with the qubit state. Isolation and efficiency are comparable to readout using a ferrite circulator, but are achieved using a chip-scale device compatible with the integration of superconducting qubits. Because the measurement result is contained in the digital state of a superconducting bifurcation amplifier, it is possible to use this scheme to create autonomous feedback loops at the cryostat base temperature. The integrated nature of this readout suggests an avenue toward the scalable measurement of larger quantum networks.

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Presenters

  • Eric Rosenthal

    University of Colorado, Boulder, JILA and the University of Colorado, Boulder, JILA and University of Colorado, Boulder

Authors

  • Eric Rosenthal

    University of Colorado, Boulder, JILA and the University of Colorado, Boulder, JILA and University of Colorado, Boulder

  • Christian M. F. Schneider

    University of Innsbruck, Univ of Innsbruck, Experimental Physics, University of Innsbruck

  • Maxime Malnou

    National Institute of Standards and Technology, NIST, Boulder

  • Ziyi Zhao

    JILA and the University of Colorado, Boulder

  • Felix Leditzky

    JILA and the University of Colorado, Boulder

  • Benjamin J. Chapman

    Physics and Applied Physics, Yale, Yale University

  • Xizheng Ma

    JILA and the University of Colorado, Boulder

  • Daniel A Palken

    JILA and the University of Colorado, Boulder, JILA and The University of Colorado, Boulder

  • Leila R. Vale

    NIST, Boulder

  • Gene C. Hilton

    NIST, Boulder, NIST Bouder

  • Gerhard Kirchmair

    University of Innsbruck, Univ of Innsbruck, Institute for Experimental Physics, University of Innsbruck, Experimental Physics, University of Innsbruck

  • Jiansong Gao

    National Institute of Standards and Technology, NIST, Boulder, National Institute of Standards and Technology Boulder

  • Graeme Smith

    JILA and the University of Colorado, Boulder

  • K. W. Lehnert

    JILA and the University of Colorado, Boulder, JILA and University of Colorado, Boulder