title: State tomography of capacitively shunted phase qubits with high fidelity.
abstract: We introduce a new design concept for superconducting phase quantum bits (qubits) in which we explicitly separate the capacitive element from the Josephson tunnel junction for improved qubit performance. The number of two-level systems that couple to the qubit is thereby reduced by an order of magnitude and the measurement fidelity improves to 90%. This improved design enables the first demonstration of quantum state tomography with superconducting qubits using single-shot measurements.
authors.affiliation: Department of Physics and California Nanosystems Institute, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Matthias
authors.initials: M
authors.lastname: Steffen
authors.forename: M
authors.initials: M
authors.lastname: Ansmann
authors.forename: R
authors.initials: R
authors.lastname: McDermott
authors.forename: N
authors.initials: N
authors.lastname: Katz
authors.forename: Radoslaw C
authors.initials: RC
authors.lastname: Bialczak
authors.forename: Erik
authors.initials: E
authors.lastname: Lucero
authors.forename: Matthew
authors.initials: M
authors.lastname: Neeley
authors.forename: E M
authors.initials: EM
authors.lastname: Weig
authors.forename: A N
authors.initials: AN
authors.lastname: Cleland
authors.forename: John M
authors.initials: JM
authors.lastname: Martinis