title: Lifetime and coherence of two-level defects in a Josephson junction.
abstract: We measure the lifetime (T₁) and coherence (T₂) of two-level defect states (TLSs) in the insulating barrier of a Josephson phase qubit and compare to the interaction strength between the two systems. We find for the average decay times a power-law dependence on the corresponding interaction strengths, whereas for the average coherence times we find an optimum at intermediate coupling strengths. We explain both the lifetime and the coherence results using the standard TLS model, including dipole radiation by phonons and anticorrelated dependence of the energy parameters on environmental fluctuations.
authors.affiliation: Racah Institute of Physics, The Hebrew University of Jerusalem, Israel.
authors.forename: Yoni
authors.initials: Y
authors.lastname: Shalibo
authors.forename: Ya'ara
authors.initials: Y
authors.lastname: Rofe
authors.forename: David
authors.initials: D
authors.lastname: Shwa
authors.forename: Felix
authors.initials: F
authors.lastname: Zeides
authors.forename: Matthew
authors.initials: M
authors.lastname: Neeley
authors.forename: John M
authors.initials: JM
authors.lastname: Martinis
authors.forename: Nadav
authors.initials: N
authors.lastname: Katz