Current Fluctuations and Electron-Electron Interactions in Coherent Conductors

TL;DR

This paper investigates how electron-electron interactions influence current fluctuations in mesoscopic coherent conductors, revealing universal dependencies and contrasting effects on Nyquist and shot noise across different transmission regimes.

Contribution

It provides explicit universal formulas for current noise dependencies on temperature, voltage, and frequency, highlighting the contrasting effects of Coulomb interactions on Nyquist and shot noise.

Findings

Coulomb interaction decreases Nyquist noise.

Interaction correction to noise depends on transmission modes.

Coulomb interaction reduces shot noise at low transmissions and increases it at high transmissions.

Abstract

We analyze current fluctuations in mesoscopic coherent conductors in the presence of electron-electron interactions. In a wide range of parameters we obtain explicit universal dependencies of the current noise on temperature, voltage and frequency. We demonstrate that Coulomb interaction decreases the Nyquist noise. In this case the interaction correction to the noise spectrum is governed by the combination $\sum_nT_n(T_n-1)$, where $T_n$ is the transmission of the $n$-th conducting mode. The effect of electron-electron interactions on the shot noise is more complicated. At sufficiently large voltages we recover two different interaction corrections entering with opposite signs. The net result is proportional to $\sum_nT_n(T_n-1)(1-2T_n)$, i.e. Coulomb interaction decreases the shot noise at low transmissions and increases it at high transmissions.