title: Suppressing spin qubit dephasing by nuclear state preparation.
abstract: Coherent spin states in semiconductor quantum dots offer promise as electrically controllable quantum bits (qubits) with scalable fabrication. For few-electron quantum dots made from gallium arsenide (GaAs), fluctuating nuclear spins in the host lattice are the dominant source of spin decoherence. We report a method of preparing the nuclear spin environment that suppresses the relevant component of nuclear spin fluctuations below its equilibrium value by a factor of approximately 70, extending the inhomogeneous dephasing time for the two-electron spin state beyond 1 microsecond. The nuclear state can be readily prepared by electrical gate manipulation and persists for more than 10 seconds.
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Reilly
authors.forename: J M
authors.initials: JM
authors.lastname: Taylor
authors.forename: J R
authors.initials: JR
authors.lastname: Petta
authors.forename: C M
authors.initials: CM
authors.lastname: Marcus
authors.forename: M P
authors.initials: MP
authors.lastname: Hanson
authors.forename: A C
authors.initials: AC
authors.lastname: Gossard