title: Localization of metal-induced gap states at the metal-insulator interface: origin of flux noise in SQUIDs and superconducting qubits.
abstract: The origin of magnetic flux noise in superconducting quantum interference devices with a power spectrum scaling as 1/f (f is frequency) has been a puzzle for over 20 years. This noise limits the decoherence time of superconducting qubits. A consensus has emerged that the noise arises from fluctuating spins of localized electrons with an areal density of 5x10(17) m(-2). We show that, in the presence of potential disorder at the metal-insulator interface, some of the metal-induced gap states become localized and produce local moments. A modest level of disorder yields the observed areal density.
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720, USA.
authors.forename: SangKook
authors.initials: S
authors.lastname: Choi
authors.forename: Dung-Hai
authors.initials: DH
authors.lastname: Lee
authors.forename: Steven G
authors.initials: SG
authors.lastname: Louie
authors.forename: John
authors.initials: J
authors.lastname: Clarke