Diagnosing errors in superconducting two-qubit gates using continuous measurements

ORAL

Abstract

Improving the fidelity of two-qubit gates is essential for performing quantum algorithms on superconducting quantum computers. By using continuous weak measurements of superconducting qubits throughout a two-qubit gate, we can reveal applied pulse shapes and coherent gate errors with high time resolution. We treat potential coherent gate errors as unknown time-dependent parameters in the Hamiltonian and estimate them by fitting the measured voltage records to a master equation. We experimentally demonstrate this method on imperfect single-qubit and parametric entangling two-qubit gates, and show that we can accurately reconstruct errors such as over-rotations and leakage out of the computational subspace. The gate fidelity can be improved by designing a correction pulse that cancels out the reconstructed error.

*We acknowledge funding from US Army Research Office grant no. W911NF-18-10178.

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Presenters

  • John Steinmetz

    • University of Rochester

Authors

  • John Steinmetz

    • University of Rochester

  • Debmalya Das

    • University of Rochester

  • Karthik Siva

    • University of California, Berkeley

  • Gerwin Koolstra

    • University of California, Berkeley

  • William P Livingston

    • University of California, Berkeley

  • Larry Chen

    • University of California, Berkeley

  • Christian Juenger

    • Lawrence Berkeley National Laboratory

  • Noah J Stevenson

    • University of California, Berkeley

  • Ravi K Naik

    • University of California, Berkeley
    • Lawrence Berkeley National Laboratory

  • David I Santiago

    • Lawrence Berkeley National Laboratory
    • Computational Research Division, Lawrence Berkeley National Lab

  • Irfan Siddiqi

    • University of California, Berkeley
    • Applied Mathematics and Computational Research and Materials Sciences Divisions, LBNL
    • Lawrence Berkeley National Laboratory
    • Applied Mathematics, Computational Research and Materials Sciences Divisions, Lawrence Berkeley National Lab

  • Andrew N Jordan

    • University of Rochester
    • Chapman University