Decoupling a spin qubit from high-frequency Larmor dynamics of a GaAs nuclear spin bath

ORAL

Abstract

We present a technique of decoupling a spin qubit in a GaAs/AlGaAs heterostructure from low- and high-frequency noise arising from hyperfine interaction of electrons with nuclear spins. We use Carr-Purcell-Meiboom-Gill sequences in which we synchronize the repetition rate of $\pi$ pulses to difference Larmor frequencies of $^{69}$Ga, $^{71}$Ga and $^{75}$As nuclei. This decouples the qubit both from low-frequency noise due to diffusion of nuclear spins and from noise at selected high frequencies, allowing us to apply more than a thousand $\pi$ pulses in a sequence. We demonstrate a coherence time of a singlet-triplet qubit of 0.87 ms, i.e. five orders of magnitude longer than the inhomogeneous dephasing time intrinsic to GaAs.

*Support through IARPA-MQCO, Army Research Office, LPS-MPO-CMTC, the Villum Foundation and the Danish National Research Foundation is acknowledged.

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Authors

  • Filip K. Malinowski

    • Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen

  • Frederico Martins

    • Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen

  • Peter D. Nissen

    • Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen

  • Mark S. Rudner

    • Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen

  • Charles M. Marcus

    • Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen

  • Ferdinand Kuemmeth

    • Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen

  • Edwin Barnes

    • Department of Physics, Virginia Tech

  • Saeed Fallahi

    • Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University

  • Geoffrey C. Gardner

    • Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University

  • Michael J. Manfra

    • Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University