Effects of capacitance on noise rounded current-voltage curves of a Josephson tunnel junction

Abstract

A theoretical study is made of the effects of a finite shunt capacitance of a Josephson tunnel junction on the noise rounding of its dc current-voltage (I-V) curves. A steady-state solution of the two-dimensional Fokker-Planck equation with a reasonable physical implication has been obtained with a trial function method. The solution leads to an analytical expression for dc I-V curves, which includes as limiting cases both the expression by Ambegaokar and Halperin in the zero-capacitance limit and that given by McCumber in the zero-noise limit. It is shown that the obtained dc I-V curves are in reasonable agreement with the results by computer simulation.