Crossover from mesoscopic to classical proximity effects, induced by particle - hole symmetry breaking in Andreev interferometers

Abstract

When two superconducting contacts are made on either side of a mesoscopic normal wire, the electrical conductance is a periodic function of the phase difference between the superconductors. For this structure, the oscillation at zero voltage and zero temperature is a small mesoscopic effect, with an amplitude of order . In contrast, we predict that a finite bias voltage V will induce giant oscillations associated with the classical proximity effect. These are a finite fraction of the overall conductance, exhibit a maximum when eV equals the Thouless energy, and decrease at higher voltages. This effect may account for the large-amplitude oscillations measured in recent experiments by Petrashov et al.