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