Low- and high-frequency noise from coherent two-level systems.
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.
Shnirman
Alexander
A
Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany.
Schön
Gerd
G
Martin
Ivar
I
Makhlin
Yuriy
Y