Nonequilibrium Fluctuation-Induced Phenomena in Josephson Junctions

We show that nonequilibrium current fluctuations of a certain type can give rise to “net” voltages in superconducting tunnel junctions. This is the result of a fluctuation-induced net rate of change of the phase difference of the superconducting order parameter across the junction. Various exact expressions are derived for the mean voltage, and are evaluated explicitly in certain limits as well as by numerical simulations. These phenomena are due to an asymmetry in the spectral properties of the current noise which should be a fairly ubiquitous feature of nonequilibrium fluctuations in nature.