Josephson current noise above Tc in superconducting tunnel junctions

TL;DR

This paper investigates how superconductive fluctuations above the critical temperature induce Josephson current noise in tunnel junctions, revealing a peak at the Josephson frequency as a precursor to superconductivity.

Contribution

It provides a theoretical analysis of the Josephson current noise spectrum above Tc, highlighting the fluctuation-induced noise peak as a novel precursor signature.

Findings

Noise spectrum peaks at Josephson frequency above Tc

Temperature dependence of noise resonance line calculated

Fluctuation-induced noise can signal superconductivity onset

Abstract

Tunnel junction between two superconductors is considered in the vicinity of the critical temperature. Superconductive fluctuations above Tc give rise to the noise of the ac Josephson current although the current itself is zero in average. As a result of fluctuations, current noise spectrum is peaked at the Josephson frequency, which may be considered as precursor of superconductivity in the normal state. Temperature dependence and shape of the Josephson current noise resonance line is calculated for various junction configurations.