Fast spin state preparation in a single charged quantum dot

ORAL

Abstract

Electron spins trapped inside of semiconductor dots (QD) are promising candidates for quantum bits (qubits). Quantum computation requires both the initialization of qubits with a high fidelity and a continuous supply of fresh ancillary qubits. The latter is the key for quantum error correction (QEC). Here, we demonstrate fast spin state preparation (laser cooling of an electron spin) in a single charged InAs self-assembled QD by applying magnetic field in the Voigt geometry. The preparation efficiency of the spin state is 98.9{\%} at a magnetic field of 0.88T, which corresponds to the cooling of spin from 5 K (experimental temperature) to 0.06 K. To reach the same efficiency by thermal equilibration, a 69 T static magnetic field should be applied. The spin cooling rate of $3\cdot 8\times 10^9s^{-1}$ is achieved. This is three orders of magnitude faster than the spin decoherence rate, which is on the order of$1\times 10^6s^{-1}$.

*This work is supported by U.S. ARO, AFOSR, ONR, LPS, and FOCUS-NSF.

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Authors

  • Xiaodong Xu

    • H. M. Randall Laboratory, The University of Michigan, Ann Arbor, MI 48109, USA
    • The H. M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109

  • Yanwen Wu

    • University of Michigan
    • H. M. Randall Laboratory, The University of Michigan, Ann Arbor, MI 48109, USA
    • The H. M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109

  • Bo Sun

    • H. M. Randall Laboratory, The University of Michigan, Ann Arbor, MI 48109, USA

  • Jun Cheng

    • H. M. Randall Laboratory, The University of Michigan, Ann Arbor, MI 48109, USA
    • The H. M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109

  • Qiong Huang

    • H. M. Randall Laboratory, The University of Michigan, Ann Arbor, MI 48109, USA

  • Duncan Steel

    • University of Michigan
    • H. M. Randall Laboratory, The University of Michigan, Ann Arbor, MI 48109, USA
    • The H. M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109

  • Allan Bracker

    • Naval Research Laboratory, Washington DC 20375

  • Dan Gammon

    • Naval Research Laboratory, Washington DC 20375
    • The Naval Research Laboratory, Washington D.C. 20375

  • Clive Emary

    • Department of Physics, The University of California, San-Diego,La Jolla, California 92093

  • L.J. Sham

    • University of California, San Diego
    • University of California San Diego
    • Department of Physics, The University of California, San-Diego,La Jolla, California 92093
    • Department of Physics, University of California, San Diego, La Jolla, California, 92093-0319