Shot Noise Current-Current Correlations in Multi-Terminal Diffusive Conductors

TL;DR

This paper explores current fluctuation correlations in multi-terminal diffusive conductors, revealing exchange effects similar to optical interference and providing a new derivation of shot noise suppression independent of dephasing.

Contribution

It introduces a novel derivation of the 1/3 shot noise suppression in two-terminal geometries and analyzes exchange effects in current correlations.

Findings

Exchange effects exist in ensemble-averaged current correlations.

Shot noise suppression is geometry-independent and valid for various wire dimensions.

Correlations are insensitive to dephasing effects.

Abstract

We investigate the correlations in the current fluctuations at different terminals of metallic diffusive conductors. We start from scattering matrix expressions for the shot noise and use the Fisher-Lee relation in combination with diagram technique to evaluate the noise correlations. Of particular interest are exchange (interference) effects analogous to the Hanbury Brown--Twiss effect in optics. We find that the exchange effect exists in the ensemble averaged current correlations. Depending on the geometry, it might have the same magnitude as the mean square current fluctuations of the shot noise. The approach which we use is first applied to present a novel derivation of the 1/3-suppression of shot noise in a two-terminal geometry, valid for an arbitrary relation between the length and wire width. We find that in all geometries correlations are insensitive to dephasing.