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Calibration of the Cross-Resonance Gate using Closed-Loop Optimal Control

ORAL

Abstract

The cross-resonance gate is an appealing entangling gate for scaling up superconducting quantum processors because of its modest hardware requirements and low error rates. However, reliably achieving coherence-limited fidelity for this gate is challenging due to the multitude of parameters to calibrate, especially in the presence of crosstalk and spectator qubits. Further, optimal parameters for the gate are sensitive to the detuning between the qubits and hence to fabrication variation. For calibrating cross-resonance gates on a large quantum processor, a method that can efficiently optimize parameters across a set of qubits with a spread of qubit frequencies and crosstalk dynamics is desired.
We present a closed-loop, optimization-based protocol to calibrate the cross-resonance gate. To simultaneously calibrate the gate parameters, we use a physically-motivated parameterized ansatz that targets the dominant error sources of the gate. With this protocol, we are able to calibrate several parameters of the gate simultaneously, for multiple pairs of qubits. The efficiency and flexibility of this protocol may simplify the calibration of larger quantum processors that use the cross-resonance gate as a native entangling operation.

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Presenters

  • Brad Mitchell

    University of California, Berkeley, Univ of California – Berkeley, University of California - Berkeley

Authors

  • Brad Mitchell

    University of California, Berkeley, Univ of California – Berkeley, University of California - Berkeley

  • Ravi K. Naik

    University of California, Berkeley, Univ of California – Berkeley, Physics, University of California, Berkeley, University of California Berkeley, Univ of California - Berkeley, Quantum Nanoelectronics Laboratory, Dept. of Physics, University of California, Berkeley, University of California - Berkeley

  • Alexis Morvan

    University of California, Berkeley, Lawrence Berkeley National Laboratory, Laboratoire de Physique des Solides, CNRS - Université Paris Saclay

  • Akel Hashim

    Univ of California – Berkeley, University of California, Berkeley, Quantum Nanoelectronics Lab, UC Berkeley, University of California - Berkeley

  • John Mark Kreikebaum

    Lawrence Berkeley National Laboratory, University of California, Berkeley, Univ of California – Berkeley, Physics, University of California, Berkeley

  • David Ivan Santiago

    Lawrence Berkeley National Laboratory, University of California, Berkeley, Lawrence Berkely National Laboratory, Quantum Nanoelectronics Laboratory, Dept. of Physics, University of California, Berkeley

  • Irfan Siddiqi

    Lawrence Berkeley National Laboratory, University of California, Berkeley, Univ of California - Berkeley, Univ of California – Berkeley, Quantum Nanoelectronics Lab, UC Berkeley, Physics, University of California, Berkeley, Quantum Nanoelectronics Laboratory, Dept. of Physics, University of California, Berkeley