title: Coherent Josephson qubit suitable for scalable quantum integrated circuits.
abstract: We demonstrate a planar, tunable superconducting qubit with energy relaxation times up to 44 μs. This is achieved by using a geometry designed to both minimize radiative loss and reduce coupling to materials-related defects. At these levels of coherence, we find a fine structure in the qubit energy lifetime as a function of frequency, indicating the presence of a sparse population of incoherent, weakly coupled two-level defects. We elucidate this defect physics by experimentally varying the geometry and by a model analysis. Our "Xmon" qubit combines facile fabrication, straightforward connectivity, fast control, and long coherence, opening a viable route to constructing a chip-based quantum computer.
authors.affiliation: Department of Physics, University of California, Santa Barbara, California 93106, USA.
authors.forename: R
authors.initials: R
authors.lastname: Barends
authors.forename: J
authors.initials: J
authors.lastname: Kelly
authors.forename: A
authors.initials: A
authors.lastname: Megrant
authors.forename: D
authors.initials: D
authors.lastname: Sank
authors.forename: E
authors.initials: E
authors.lastname: Jeffrey
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
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authors.initials: Y
authors.lastname: Yin
authors.forename: B
authors.initials: B
authors.lastname: Chiaro
authors.forename: J
authors.initials: J
authors.lastname: Mutus
authors.forename: C
authors.initials: C
authors.lastname: Neill
authors.forename: P
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authors.lastname: O'Malley
authors.forename: P
authors.initials: P
authors.lastname: Roushan
authors.forename: J
authors.initials: J
authors.lastname: Wenner
authors.forename: T C
authors.initials: TC
authors.lastname: White
authors.forename: A N
authors.initials: AN
authors.lastname: Cleland
authors.forename: John M
authors.initials: JM
authors.lastname: Martinis