title: Enhanced quantum state detection efficiency through quantum information processing.
abstract: We investigate theoretically and experimentally how quantum state-detection efficiency is improved by the use of quantum information processing (QIP). Experimentally, we encode the state of one 9Be(+) ion qubit with one additional ancilla qubit. By measuring both qubits, we reduce the state-detection error in the presence of noise. The deviation from the theoretically allowed reduction is due to infidelities of the QIP operations. Applying this general scheme to more ancilla qubits suggests that error in the individual qubit measurements need not be a limit to scalable quantum computation.
authors.affiliation: National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, USA. tschaetz@mpq.mpg.de
authors.forename: T
authors.initials: T
authors.lastname: Schaetz
authors.forename: M D
authors.initials: MD
authors.lastname: Barrett
authors.forename: D
authors.initials: D
authors.lastname: Leibfried
authors.forename: J
authors.initials: J
authors.lastname: Britton
authors.forename: J
authors.initials: J
authors.lastname: Chiaverini
authors.forename: W M
authors.initials: WM
authors.lastname: Itano
authors.forename: J D
authors.initials: JD
authors.lastname: Jost
authors.forename: E
authors.initials: E
authors.lastname: Knill
authors.forename: C
authors.initials: C
authors.lastname: Langer
authors.forename: D J
authors.initials: DJ
authors.lastname: Wineland