title: Quantum phase tomography of a strongly driven qubit.
abstract: The interference between repeated Landau-Zener transitions in a qubit swept through an avoided level crossing results in Stückelberg oscillations in qubit magnetization, a hallmark of the coherent strongly driven regime in two-level systems. The two-dimensional Fourier transforms of the resulting oscillatory patterns are found to exhibit a family of one-dimensional curves in Fourier space, in agreement with recent observations in a superconducting qubit. We interpret these images in terms of time evolution of the quantum phase of the qubit state and show that they can be used to probe dephasing mechanisms.
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Rudner
authors.forename: A V
authors.initials: AV
authors.lastname: Shytov
authors.forename: L S
authors.initials: LS
authors.lastname: Levitov
authors.forename: D M
authors.initials: DM
authors.lastname: Berns
authors.forename: W D
authors.initials: WD
authors.lastname: Oliver
authors.forename: S O
authors.initials: SO
authors.lastname: Valenzuela
authors.forename: T P
authors.initials: TP
authors.lastname: Orlando