title: Controlling the spontaneous emission of a superconducting transmon qubit.
abstract: We present a detailed characterization of coherence in seven transmon qubits in a circuit QED architecture. We find that spontaneous emission rates are strongly influenced by far off-resonant modes of the cavity and can be understood within a semiclassical circuit model. A careful analysis of the spontaneous qubit decay into a microwave transmission-line cavity can accurately predict the qubit lifetimes over 2 orders of magnitude in time and more than an octave in frequency. Coherence times T1 and T_{2};{*} of more than a microsecond are reproducibly demonstrated.
authors.affiliation: Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Houck
authors.forename: J A
authors.initials: JA
authors.lastname: Schreier
authors.forename: B R
authors.initials: BR
authors.lastname: Johnson
authors.forename: J M
authors.initials: JM
authors.lastname: Chow
authors.forename: Jens
authors.initials: J
authors.lastname: Koch
authors.forename: J M
authors.initials: JM
authors.lastname: Gambetta
authors.forename: D I
authors.initials: DI
authors.lastname: Schuster
authors.forename: L
authors.initials: L
authors.lastname: Frunzio
authors.forename: M H
authors.initials: MH
authors.lastname: Devoret
authors.forename: S M
authors.initials: SM
authors.lastname: Girvin
authors.forename: R J
authors.initials: RJ
authors.lastname: Schoelkopf