Thermal fluctuations in superconducting nanowires

TL;DR

This paper reevaluates thermally activated phase slips in thin superconducting wires near the critical temperature, providing a more accurate rate estimate and a formula for voltage noise, with implications for experimental verification.

Contribution

It introduces an effective action approach that yields higher TAPS rates than previous TDGL-based analyses, especially near the critical current.

Findings

TAPS rate exceeds previous estimates by a factor of (1-T/T_C)^{-1}

Derived a simple voltage noise formula in terms of TAPS rate

Results are testable with modern superconducting nanowire experiments

Abstract

We re-analyze the problem of thermally activated phase slips (TAPS) which can dominate the behavior of sufficiently thin superconducting wires at temperatures close to $T_C$. With the aid of an effective action approach we evaluate the TAPS rate which turns out to exceed the rate found by D.E. McCumber and B.I. Halperin, Phys. Rev. B {\bf 1}, 1054 (1970) within the TDGL analysis by the factor $\sim (1-T/T_C)^{-1} \gg 1$. Additional differences in the results of these two approaches arise at bias currents close to the Ginzburg-Landau critical current where the TAPS rate becomes bigger. We also derive a simple formula for the voltage noise across the superconducting wire in terms of the TAPS rate. Our results can be verified in modern experiments with superconducting nanowires.