Tomography of universal two-qubit logic operations in exchange-coupled donor electron spin qubits

ORAL

Abstract

Scalable quantum processors require high-fidelity universal quantum logic operations, in a manufacturable physical platform. The spin of an electron bound to a single donor atom in silicon has shown coherence times of almost a second, with single qubit quantum operation fidelities of over 99.9%. Here we present the experimental demonstration and tomography of universal 1- and 2-qubit gates in a system of two weakly exchange-coupled electrons, with each electron bound to a single donor phosphorus nucleus. By deterministically preparing the two nuclear spins in opposite directions, each electron spin resonance pulse constitutes a native conditional two-qubit gate. We carefully benchmark the fidelity of these native operations using the technique of gate set tomography (GST), achieving qubit gate fidelities above 99% for both electrons separately. We show that, as a result of working in the weak exchange regime, this coupling mechanism has negligible effect on qubit coherence. The GST method provides precious insights into the nature of the residual errors, and informs strategies for further improvement.

*Funded by the Australian Research Council (CE170100012), US Army Research Office (W911NF-17-1-0200) and Australian Department of Industry, Innovation and Science (AUSMURI000002)

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Presenters

  • Holly G Stemp

    • University of New South Wales

Authors

  • Holly G Stemp

    • University of New South Wales

  • Serwan Asaad

    • University of New South Wales

  • Mark A Johnson

    • University of New South Wales

  • Mateusz T Mądzik

    • University of New South Wales

  • Amber J Heskes

    • University of New South Wales

  • Hannes R Firgau

    • School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney NSW 2052, Australia
    • University of New South Wales

  • Arne Laucht

    • University of New South Wales

  • Kenneth M Rudinger

    • Sandia National Laboratories

  • Robin J Blume-Kohout

    • Sandia National Laboratories

  • Fay E Hudson

    • University of New South Wales
    • Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Sydney, New South Wales 2052, Australia.

  • Andrew S Dzurak

    • University of New South Wales
    • Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Sydney, New South Wales 2052, Australia.

  • Kohei M Itoh

    • Keio Univ
    • School of Fundamental Science and Technology, Keio University, Kohoku-ku, Yokohama, Japan.
    • Keio University

  • Alexander M Jacob

    • School of Physics, University of Melbourne, Parkville VIC 3010, Australia
    • University of Melbourne

  • Brett C Johnson

    • School of Physics, University of Melbourne
    • University of Melbourne
    • RMIT

  • David N Jamieson

    • School of Physics, University of Melbourne, Parkville VIC 3010, Australia
    • University of Melbourne
    • School of Physics, University of Melbourne, Melbourne, VIC 3010, Australia.

  • Andrea Morello

    • School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney NSW 2052, Australia
    • School of Electrical Engineering and Telecommunications, UNSW Sydney
    • University of New South Wales
    • Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Sydney, New South Wales 2052, Australia.