Correlators in simultaneous measurement of non-commuting qubit observables

ORAL

Abstract

We consider simultaneous continuous measurement of non-commuting qubit observables and analyze multi-time correlators $\langle i_{\kappa_1}(t_1)\cdots i_{\kappa_N}(t_N )\rangle$ for output signals $i_\kappa(t)$ from the detectors. Both informational ("spooky") and phase backactions from cQED-type measurements with phase-sensitive amplifiers are taken into account. We find an excellent agreement between analytical results and experimental data for two-time correlators of the output signals from simultaneous measurement of qubit observables $\sigma_x$ and $\sigma_\varphi = \sigma_x\cos\varphi + \sigma_y\sin\varphi$. The correlators can be used to extract small deviations of experimental parameters, e.g., phase backaction and residual Rabi frequency. The multi-time correlators are important in analysis of Bacon-Shor error correction/detection codes, operated with continuous measurements.

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Authors

  • Juan Atalaya

    • University of California, Riverside

  • Shay Hacohen-Gourgy

    • University of California
    • Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, CA 94720, USA.
    • University of California, Berkeley
    • Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley CA 94720, USA.
    • Quantum Nanoelectronics Laboratory,Department of Physics, University of California, Berkeley

  • Leigh Martin

    • Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, CA 94720, USA.
    • University of California, Berkeley
    • Quantum Nanoelectronics Laboratory,Department of Physics, University of California, Berkeley
    • Univ of California - Berkeley
    • Quantum Nanoelectronics Lab, Center for Quantum Coherent Sciences, UC Berkeley

  • Irfan Siddiqi

    • Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley CA 94720, USA
    • Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, CA 94720, USA.
    • Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley CA 94720, USA.
    • University of California, Berkeley
    • Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, California 94720, USA.
    • Quantum Nanoelectronics Laboratory
    • Quantum Nanoelectronics Laboratory,Department of Physics, University of California, Berkeley
    • Quantum Nanoelectronics Lab, Center for Quantum Coherent Sciences, UC Berkeley

  • Alexander Korotkov

    • University of California, Riverside
    • University of California at Riverside