Negative 4-Probe Conductances of Mesoscopic Superconducting Wires

TL;DR

This paper predicts that mesoscopic superconducting wires can exhibit large negative 4-probe conductances, contrasting with normal wires which show positive, exponentially small conductances in the localized regime.

Contribution

It introduces the prediction of negative 4-probe conductance values in superconducting wires, highlighting a distinct behavior from normal wires in mesoscopic systems.

Findings

Superconducting wires can have large negative 4-probe conductances.

Normal wires' conductance remains positive and exponentially small in the localized regime.

Negative conductance is predicted in both weakly disordered and localized regimes.

Abstract

We analyze the longitudinal 4-probe conductance of mesoscopic normal and superconducting wires and predict that in the superconducting case, large negative values can arise for both the weakly disordered and localized regimes. This contrasts sharply with the behaviour of the longitudinal 4-probe conductance of normal wires, which in the localized limit is always exponentially small and positive.