title: Low- and high-frequency noise from coherent two-level systems.
abstract: Recent experiments indicate a connection between the low- and high-frequency noises affecting superconducting quantum systems. We explore the possibilities that both noises can be produced by one ensemble of microscopic modes, made up, e.g., by sufficiently coherent two-level systems (TLS's). This implies a relation between the noise power in different frequency domains, which depends on the distribution of the parameters of the TLS's. We show that a distribution, natural for tunneling TLS's, with a log-uniform distribution in the tunnel splitting and linear distribution in the bias, accounts for experimental observations.
authors.affiliation: Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Shnirman
authors.forename: Gerd
authors.initials: G
authors.lastname: Schön
authors.forename: Ivar
authors.initials: I
authors.lastname: Martin
authors.forename: Yuriy
authors.initials: Y
authors.lastname: Makhlin