Improving Fidelity in Superconducting Xmon Qubits: Decreasing 1/f Flux Noise

ORAL

Abstract

Two qubit CZ gate fidelity in our superconducting Xmon qubits is currently 99.4$\%$. To achieve 99.9$\%$ fidelity, experiments indicate that we need to reduce 1/f flux noise. We present measurements of 1/f flux noise on the Xmon from sub-Hz to MHz frequencies. At low frequencies we measure an f$^{-1.0}$ frequency dependence, which is in agreement with previous phase qubit measurements but significantly different from the f$^{-0.7}$ dependence seen in SQUIDs. We also see a dependence on geometry that agrees with a theory of magnetic defects; this points toward a qubit design that will minimize dephasing.

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Authors

  • Peter O'Malley

    • Univ of California - Santa Barbara
    • University of California, Santa Barbara

  • Rami Barends

    • University of California, Santa Barbara

  • Ben Chiaro

    • University of California, Santa Barbara

  • Yu Chen

    • University of California, Santa Barbara

  • Evan Jeffrey

    • University of California, Santa Barbara

  • Julian Kelley

    • University of California, Santa Barbara

  • Anthony Megrant

    • University of California, Santa Barbara

  • Josh Mutus

    • University of California, Santa Barbara

  • Charles Neill

    • University of California, Santa Barbara

  • Pedram Roushan

    • University of California, Santa Barbara

  • Daniel Sank

    • University of California, Santa Barbara

  • James Wenner

    • University of California, Santa Barbara

  • Theodore White

    • University of California, Santa Barbara

  • Andrew Cleland

    • University of California, Santa Barbara

  • John Martinis

    • University of California, Santa Barbara