title: Two-axis control of a singlet-triplet qubit with an integrated micromagnet.
abstract: The qubit is the fundamental building block of a quantum computer. We fabricate a qubit in a silicon double-quantum dot with an integrated micromagnet in which the qubit basis states are the singlet state and the spin-zero triplet state of two electrons. Because of the micromagnet, the magnetic field difference ΔB between the two sides of the double dot is large enough to enable the achievement of coherent rotation of the qubit's Bloch vector around two different axes of the Bloch sphere. By measuring the decay of the quantum oscillations, the inhomogeneous spin coherence time T2* is determined. By measuring T2* at many different values of the exchange coupling J and at two different values of ΔB, we provide evidence that the micromagnet does not limit decoherence, with the dominant limits on T2* arising from charge noise and from coupling to nuclear spins.
authors.affiliation: Departments of Physics and.
authors.forename: Xian
authors.initials: X
authors.lastname: Wu
authors.affiliation: Departments of Physics and.
authors.forename: D R
authors.initials: DR
authors.lastname: Ward
authors.affiliation: Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom.
authors.forename: J R
authors.initials: JR
authors.lastname: Prance
authors.affiliation: Departments of Physics and.
authors.forename: Dohun
authors.initials: D
authors.lastname: Kim
authors.affiliation: Departments of Physics and.
authors.forename: John King
authors.initials: JK
authors.lastname: Gamble
authors.affiliation: Departments of Physics and.
authors.forename: R T
authors.initials: RT
authors.lastname: Mohr
authors.affiliation: Departments of Physics and.
authors.forename: Zhan
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Materials Science and Engineering, University of Wisconsin, Madison, WI 53706; and.
authors.forename: D E
authors.initials: DE
authors.lastname: Savage
authors.affiliation: Materials Science and Engineering, University of Wisconsin, Madison, WI 53706; and.
authors.forename: M G
authors.initials: MG
authors.lastname: Lagally
authors.affiliation: Departments of Physics and.
authors.forename: Mark
authors.initials: M
authors.lastname: Friesen
authors.affiliation: Departments of Physics and snc@physics.wisc.edu maeriksson@wisc.edu.
authors.forename: S N
authors.initials: SN
authors.lastname: Coppersmith
authors.affiliation: Departments of Physics and snc@physics.wisc.edu maeriksson@wisc.edu.
authors.forename: M A
authors.initials: MA
authors.lastname: Eriksson
keywords: quantum nanoelectronics; semiconductor spin qubit
references.citation: Science. 2005 Sep 30;309(5744):2180-4
references.pmid: 16141370
references.citation: Nature. 2013 May 2;497(7447):91-4
references.pmid: 23636400
references.citation: Phys Rev Lett. 2002 Sep 30;89(14):147902
references.pmid: 12366076
references.citation: Science. 2011 Sep 2;333(6047):1269-72
references.pmid: 21817015
references.citation: Phys Rev Lett. 2009 Oct 16;103(16):160503
references.pmid: 19905680
references.citation: Phys Rev Lett. 2010 Dec 10;105(24):246804
references.pmid: 21231547
references.citation: Nano Lett. 2009 Sep;9(9):3234-8
references.pmid: 19645459
references.citation: Science. 2012 Apr 13;336(6078):202-5
references.pmid: 22499942
references.citation: Phys Rev Lett. 2010 Mar 5;104(9):096801
references.pmid: 20367000
references.citation: Nat Nanotechnol. 2013 Sep;8(9):654-9
references.pmid: 23995458
references.citation: Nature. 2011 Nov 16;479(7373):345-53
references.pmid: 22094695
references.citation: Phys Rev Lett. 2012 Apr 6;108(14):140503
references.pmid: 22540779
references.citation: Nat Commun. 2014;5:3020
references.pmid: 24389977
references.citation: Nat Commun. 2013;4:1401
references.pmid: 23360992
references.citation: Science. 2010 Feb 5;327(5966):669-72
references.pmid: 20133567
references.citation: Phys Rev Lett. 2013 Apr 5;110(14):146804
references.pmid: 25167023
references.citation: Nature. 2014 Jul 3;511(7507):70-4
references.pmid: 24990747
references.citation: Phys Rev Lett. 2012 Jun 1;108(22):226802
references.pmid: 23003637
references.citation: Nature. 2012 Sep 27;489(7417):541-5
references.pmid: 22992519
references.citation: Nature. 2012 Jan 18;481(7381):344-7
references.pmid: 22258613
references.citation: Phys Rev Lett. 2010 Dec 31;105(26):266808
references.pmid: 21231704
references.citation: Phys Rev Lett. 2012 Jan 27;108(4):046808
references.pmid: 22400879
references.citation: Nat Commun. 2013;4:2017
references.pmid: 23774081
references.citation: Science. 2008 Aug 8;321(5890):817-21
references.pmid: 18687959