title: Gate fidelity and coherence of an electron spin in an Si/SiGe quantum dot with micromagnet.
abstract: The gate fidelity and the coherence time of a quantum bit (qubit) are important benchmarks for quantum computation. We construct a qubit using a single electron spin in an Si/SiGe quantum dot and control it electrically via an artificial spin-orbit field from a micromagnet. We measure an average single-qubit gate fidelity of ∼99% using randomized benchmarking, which is consistent with dephasing from the slowly evolving nuclear spins in the substrate. The coherence time measured using dynamical decoupling extends up to ∼400 μs for 128 decoupling pulses, with no sign of saturation. We find evidence that the coherence time is limited by noise in the 10-kHz to 1-MHz range, possibly because charge noise affects the spin via the micromagnet gradient. This work shows that an electron spin in an Si/SiGe quantum dot is a good candidate for quantum information processing as well as for a quantum memory, even without isotopic purification.
authors.affiliation: QuTech, 2628 CJ Delft, The Netherlands; Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, The Netherlands.
authors.forename: Erika
authors.initials: E
authors.lastname: Kawakami
authors.affiliation: QuTech, 2628 CJ Delft, The Netherlands; Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, The Netherlands.
authors.forename: Thibaut
authors.initials: T
authors.lastname: Jullien
authors.affiliation: QuTech, 2628 CJ Delft, The Netherlands; Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, The Netherlands.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Scarlino
authors.affiliation: University of Wisconsin-Madison, Madison, WI 53706.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Ward
authors.affiliation: University of Wisconsin-Madison, Madison, WI 53706.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Savage
authors.affiliation: University of Wisconsin-Madison, Madison, WI 53706.
authors.forename: Max G
authors.initials: MG
authors.lastname: Lagally
authors.affiliation: Ames Laboratory, US Department of Energy, Iowa State University, Ames, IA 50011.
authors.forename: Viatcheslav V
authors.initials: VV
authors.lastname: Dobrovitski
authors.affiliation: University of Wisconsin-Madison, Madison, WI 53706.
authors.forename: Mark
authors.initials: M
authors.lastname: Friesen
authors.affiliation: University of Wisconsin-Madison, Madison, WI 53706; snc@physics.wisc.edu l.m.k.vandersypen@tudelft.nl.
authors.forename: Susan N
authors.initials: SN
authors.lastname: Coppersmith
authors.affiliation: University of Wisconsin-Madison, Madison, WI 53706.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Eriksson
authors.affiliation: QuTech, 2628 CJ Delft, The Netherlands; Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, The Netherlands; Components Research, Intel Corporation, Hillsboro, OR 97124 snc@physics.wisc.edu l.m.k.vandersypen@tudelft.nl.
authors.forename: Lieven M K
authors.initials: LM
authors.lastname: Vandersypen
keywords: Si/SiGe quantum dot; dynamical decoupling; electron spin; qubit; randomized benchmarking