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.
@article{arxiv.cond-mat/9703114,
title = {On the absence of Shapiro-like steps in certain mesoscopic S-N-S junctions},
author = {J. G. E. Harris and N. Argaman and S. J. Allen},
journal= {arXiv preprint arXiv:cond-mat/9703114},
year = {2009}
}