We present a theory of current-reducing fluctuations in narrow superconducting channels. The theory is based on the Ginzburg-Landau equation, and is constructed in analogy with the droplet model of the condensation of a supersaturated vapor. Our theory suggests that large and improbable fluctuations are important, and cause measurable departures from the mean-field critical current. The calculation leads to a concrete result for the intrinsic resistive transition. This transition is predicted to occur at a temperature slightly lower than the bulk transition temperature, and to have a width which is observable but smaller than those measured in recent experiments.

• Received 19 June 1967

DOI:https://doi.org/10.1103/PhysRev.164.498