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.

*This work is supported by the ARO under contract W911NF-14-1-0079 and the National Science Foundation under Grant No. 1125844. E.I.R. acknowledges support from the ARO QuaCGR fellowship.

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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