Coherent operations and screening in multielectron spin qubits.
Multielectron spin qubits are demonstrated, and performance examined by comparing coherent exchange oscillations in coupled single-electron and multielectron quantum dots, measured in the same device. Fast (>1  GHz) exchange oscillations with a quality factor Q∼15 are found for the multielectron case, compared to Q∼2 for the single-electron case, the latter consistent with experiments in the literature. A model of dephasing that includes voltage and hyperfine noise is developed that is in good agreement with both single- and multielectron data, though in both cases additional exchange-independent dephasing is needed to obtain quantitative agreement across a broad parameter range.
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA and Center for Quantum Devices, Niels Bohr Institute, 2100 Copenhagen, Denmark.
A P
AP
Higginbotham
Center for Quantum Devices, Niels Bohr Institute, 2100 Copenhagen, Denmark.
F
F
Kuemmeth
Materials Department, University of California, Santa Barbara, California 93106, USA.
M P
MP
Hanson
Materials Department, University of California, Santa Barbara, California 93106, USA.
A C
AC
Gossard
Center for Quantum Devices, Niels Bohr Institute, 2100 Copenhagen, Denmark.
C M
CM
Marcus