Large energy dependence of current noise in superconducting/normal metal junctions

摘要

Interference of electronic waves undergoing Andreev reflection in diffusiveconductors determines the energy profile of the conductance on the scale of theThouless energy. A similar dependence exists in the current noise, but itsbehavior is known only in few limiting cases. We consider a metallic diffusivewire connected to a superconducting reservoir through an interfacecharacterized by an arbitrary distribution of channel transparencies. Withinthe quasiclassical theory for current fluctuations we provide a generalexpression for the energy dependence of the current noise. We derive closedanalytical expressions for large energy.