Non-Dispersive Limit of the Qubit Readout with a Microwave Photon Counter.

ORAL

Abstract

The Josephson photomultiplier (JPM) provides a path to fast, high fidelity qubit readout [Govia et al, Phys. Rev. A 90, 062307 (2014)]. The measurement protocol requires the creation of cavity pointer states with high contrast in photon occupation. For such large pointer states the dispersive approximation to the Jaynes-Cummings Hamiltonian breaks down. In this regime, the non-dispersive terms reduce the pointer-states contrast and lead to backaction of the measurement on the qubit state, reducing the readout accuracy and affecting its QND nature. We discuss the optimal conditions for JPM-based qubit readout in terms of the microwave drive parameters, the cavity photon decay time, and the detuning between the cavity and qubit. We also show that strong cavity drive facilitates reset of the readout system.

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Presenters

  • Maxim Vavilov

    Physics, University of Wisconsin-Madison, Department of Physics, University of Wisconsin-Madison, Univ of Wisconsin, Madison, University of Wisconsin-Madison, Physics, University of Wisconsin Madison

Authors

  • Konstantin Nesterov

    University of Wisconsin-Madison, Univ of Wisconsin, Madison

  • Alexander Opremcak

    Univ of Wisconsin, Madison, Physics, University of Wisconsin Madison, University of Wisconsin-Madison

  • Ivan Pechenezhskiy

    Univ of Wisconsin, Madison, University of Maryland, University of Maryland, College Park, Physics, University of Wisconsin Madison

  • Robert McDermott

    Univ of Wisconsin, Madison, Physics, University of Wisconsin - Madison, Physics, University of Wisconsin-Madison, Physics, Univ of Wisconsin-Madison, Physics, University of Wisconsin Madison, University of Wisconsin-Madison

  • Maxim Vavilov

    Physics, University of Wisconsin-Madison, Department of Physics, University of Wisconsin-Madison, Univ of Wisconsin, Madison, University of Wisconsin-Madison, Physics, University of Wisconsin Madison