title: High-coherence hybrid superconducting qubit.
abstract: We report quantum coherence measurements of a superconducting qubit whose design is a hybrid of several existing types. Excellent coherence times are found: T2∼T1∼1.5 μs. The topology of the qubit is that of a traditional three-junction flux qubit, but it has a large shunting capacitance, and the ratio of the junction critical currents is chosen so that the qubit potential has a single-well form. The qubit has a sizable nonlinearity, but its sign is reversed compared with most other popular qubit designs. The qubit is read out dispersively using a high-Q resonator in a λ/2 configuration.
authors.affiliation: IBM Watson Research Center, Yorktown Heights, New York 10598, USA.
authors.forename: Matthias
authors.initials: M
authors.lastname: Steffen
authors.forename: Shwetank
authors.initials: S
authors.lastname: Kumar
authors.forename: David P
authors.initials: DP
authors.lastname: Divincenzo
authors.forename: J R
authors.initials: JR
authors.lastname: Rozen
authors.forename: George A
authors.initials: GA
authors.lastname: Keefe
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Rothwell
authors.forename: Mark B
authors.initials: MB
authors.lastname: Ketchen