Noise in Multiterminal Diffusive Conductors: Universality, Nonlocality and Exchange Effects

TL;DR

This paper demonstrates the universality and nonlocal nature of shot-noise in multiterminal diffusive conductors, revealing exchange effects without quantum coherence and proposing experiments to measure noise temperature.

Contribution

It introduces a Boltzmann-Langevin approach to analyze shot-noise, proving its universality and uncovering exchange effects in diffusive conductors.

Findings

Shot-noise is universal in multiterminal diffusive conductors.

Exchange effects can occur without quantum phase coherence.

Current noise can be induced by thermal transport.

Abstract

We study noise and transport in multiterminal diffusive conductors. Using a Boltzmann-Langevin equation approach we reduce the calculation of shot-noise correlators to the solution of diffusion equations. Within this approach we prove the universality of shot-noise in multiterminal diffusive conductors of arbitrary shape and dimension for purely elastic scattering as well as for hot electrons. We show that shot-noise in multiterminal conductors is a non-local quantity and that exchange effects can occur in the absence of quantum phase coherence even at zero electron temperature. It is also shown that the exchange effect measured in one contact is always negative -- in agreement with the Pauli principle. We discuss a new phenomenon in which current noise is induced by thermal transport. We propose a possible experiment to measure locally the effective noise temperature. Concrete numbers for shot-noise are given that can be tested experimentally.