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

TL;DR

This paper investigates how the current noise in superconducting/normal metal junctions varies with energy, providing a comprehensive theoretical framework that extends understanding beyond limited previous cases.

Contribution

It introduces a general quasiclassical theory expression for energy-dependent current noise in diffusive conductors with arbitrary interface transparencies.

Findings

Derived analytical expressions for current noise at high energies.

Revealed the significant energy dependence of noise in these junctions.

Extended theoretical understanding of noise beyond known limiting cases.

Abstract

Interference of electronic waves undergoing Andreev reflection in diffusive conductors determines the energy profile of the conductance on the scale of the Thouless energy. A similar dependence exists in the current noise, but its behavior is known only in few limiting cases. We consider a metallic diffusive wire connected to a superconducting reservoir through an interface characterized by an arbitrary distribution of channel transparencies. Within the quasiclassical theory for current fluctuations we provide a general expression for the energy dependence of the current noise. We derive closed analytical expressions for large energy.