We evaluate the average and the standard deviation of the supercurrent in superconducting nanobridges, as functions of temperature, phase difference, and sample parameters, in an equilibrium situation. We also evaluate the autocorrelation of the supercurrent as a function of the elapsed time. The behavior of supercurrent fluctuations is qualitatively different from that of the normal current: they depend on the phase difference, have a different temperature dependence, have nonzero averages, and for an appropriate range their standard deviation is independent of the probing time. We considered two radically different filaments and obtained very similar results for both. Fluctuations of the supercurrent can in principle be measured.

• Received 6 October 2011

DOI:https://doi.org/10.1103/PhysRevB.85.144507