Current noise in superconductor-normal metal-superconductor (SNS) junctions is calculated within the scattering theory of multiple Andreev reflections (MAR). It is shown that the noise exhibits subharmonic gap singularities at eV=2Δ/n, n=1,2,... both in single-mode junctions with arbitrary transparency D and in multi-mode disordered junctions. The subharmonic structure is superimposed with monotonic increase of the effective transferred charge q∗=SI(0)/2I with decreasing bias voltage. Other features of the noise include a step-like increase of q∗ in junctions with small D, and a divergence SI(0)∝V−1/2 at small voltages and excess noise Sex=2eIex, where Iex is the excess current, at large voltages, in junctions with diffusive transport.
@article{arxiv.cond-mat/9902202,
title = {Non-equilibrium current noise in mesoscopic disordered SNS junctions},
author = {Y. Naveh and D. V. Averin},
journal= {arXiv preprint arXiv:cond-mat/9902202},
year = {2009}
}