On the absence of Shapiro-like steps in certain mesoscopic S-N-S junctions

TL;DR

This paper discusses the limitations of phase-dependent conductance in mesoscopic S-N-S junctions, showing it cannot produce Shapiro steps despite causing AC currents, and highlights the temperature effects on Josephson coupling.

Contribution

It reveals that phase-dependent conductance alone does not generate Shapiro steps in certain mesoscopic S-N-S junctions, clarifying a misconception in the field.

Findings

Josephson coupling decreases exponentially with temperature.

Phase dependence of conductance persists at higher temperatures, decreasing as 1/T.

Phase-dependent conductance does not produce Shapiro steps.

Abstract

In DC transport through mesoscopic S-N-S junctions, it is known that the Josephson coupling decreases exponentially with increasing temperature, but the phase dependence of the conductance persists to much higher temperatures and decreases only as 1/T. It is pointed out here that, despite the fact that such a phase-dependent conductance does bring about an AC current for a pure DC voltage, it cannot, by itself, lead to the formation of Shapiro steps.