Universal stabilization of single-qubit states using a tunable coupler

ORAL

Abstract

We theoretically analyze a scheme for fast stabilization of arbitrary qubit states with high fidelities, extending a protocol recently demonstrated experimentally [1]. Our scheme utilizes red and blue sideband transitions in a system composed of a fixed-frequency transmon qubit, a low-Q LC-oscillator, and a coupler enabling us to tune the interaction between them. Under parametric modulations of the coupling strength, the qubit can be steered into any desired pure or mixed single-qubit state. For realistic circuit parameters, we predict that stabilization can be achieved within 100 ns. By varying the ratio between the oscillator's damping rate and the effective qubit-oscillator coupling strength, we can switch between under-damped, critically-damped, and over-damped stabilization and find optimal working points. We further analyze the effect of thermal fluctuations and show that the stabilization scheme remains robust for realistic temperatures.

[1] Yao Lu, S. Chakram, N. Leung, N. Earnest, R. K. Naik, Ziwen Huang, Peter Groszkowski, Eliot Kapit, Jens Koch, and David I. Schuster, Phys. Rev. Lett. 119, 150502 (2017)

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Presenters

  • Ziwen Huang

    • Department of Physics and Astronomy, Northwestern Univ
    • Department of Physics & Astronomy, Northwestern University

Authors

  • Ziwen Huang

    • Department of Physics and Astronomy, Northwestern Univ
    • Department of Physics & Astronomy, Northwestern University

  • Yao Lu

    • James Franck Institute and Department of Physics, University of Chicago
    • University of Chicago
    • Univ of Chicago
    • James Franck Institute, University of Chicago
    • Physics, University of Chicago

  • Eliot Kapit

    • Physics and Engineering Physics, Tulane University
    • Tulane University
    • Department of Physics & Engineering Physics, Tulane University

  • David Schuster

    • Univ of Chicago
    • Physics, Univ of Chicago
    • James Franck Institute and Department of Physics, University of Chicago
    • University of Chciago
    • Physics, University of Chicago
    • Institute for Molecular Engineering, University of Chicago
    • University of Chicago
    • James Franck Institute, University of Chicago

  • Jens Koch

    • Northwestern Univeristy
    • Department of Physics and Astronomy, Northwestern University
    • Department of Physics and Astronomy, Northwestern Univ
    • Department of Physics & Astronomy, Northwestern University
    • Northwestern University
    • Physics, Northwestern University