title: Scaling of dynamical decoupling for spin qubits.
abstract: We investigate the scaling of coherence time T(2) with the number of π pulses n(π) in a singlet-triplet spin qubit using Carr-Purcell-Meiboom-Gill (CPMG) and concatenated dynamical decoupling (CDD) pulse sequences. For an even numbers of CPMG pulses, we find a power law T(2) is proportional to (n(π))(γ(e)), with γ(e)=0.72±0.01, essentially independent of the envelope function used to extract T(2). From this surprisingly robust value, a power-law model of the noise spectrum of the environment, S(ω)~ω(-β), yields β=γ(e)/(1-γ(e))=2.6±0.1. Model values for T(2)(n(π)) using β=2.6 for CPMG with both even and odd n(π) up to 32 and CDD orders 3 through 6 compare very well with the experiment.
authors.affiliation: Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: J
authors.initials: J
authors.lastname: Medford
authors.forename: Ł
authors.initials: Ł
authors.lastname: Cywiński
authors.forename: C
authors.initials: C
authors.lastname: Barthel
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