Polaronic effects and thermally enhanced weak superconductivity

Abstract

We theoretically analyze the d.c. Josephson current between two superconductors connected by a vibrating weak link. Assuming the weak link to be a ``quantum dot'', we predict that the critical current is thermally enhanced at low temperatures if the electron-vibron interaction is strong and has an anomalous temperature dependence in a large temperature interval. We estimate that this unusual behavior, which occurs because the current through the weak link is carried by ``polaronic'' Andreev states, is measurable in experiments on, e.g., carbon-nanotube-based Josephson junctions.