title: Energy relaxation time between macroscopic quantum levels in a superconducting persistent-current qubit.
abstract: We measured the intrawell energy relaxation time tau(d) approximately 24 micros between macroscopic quantum levels in the double well potential of a Nb persistent-current qubit. Interwell population transitions were generated by irradiating the qubit with microwaves. Zero population in the initial well was then observed due to a multilevel decay process in which the initial population relaxed to lower energy levels during the driven transitions. The decoherence time, estimated from tau(d) within the spin-boson model, is about 20 micros for this configuration with a Nb superconducting qubit.
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.forename: D
authors.initials: D
authors.lastname: Nakada
authors.forename: Janice C
authors.initials: JC
authors.lastname: Lee
authors.forename: Bhuwan
authors.initials: B
authors.lastname: Singh
authors.forename: D S
authors.initials: DS
authors.lastname: Crankshaw
authors.forename: T P
authors.initials: TP
authors.lastname: Orlando
authors.forename: Karl K
authors.initials: KK
authors.lastname: Berggren
authors.forename: William D
authors.initials: WD
authors.lastname: Oliver