Finite frequency noise properties of the non-equilibrium Anderson impurity model

TL;DR

This paper investigates the finite frequency noise spectrum of the Anderson impurity model under non-equilibrium conditions, revealing how electron interactions and voltage influence noise characteristics, including suppression, amplification, and Kondo-related peaks.

Contribution

It provides analytic perturbative and non-perturbative results for the noise spectrum, highlighting the effects of interactions and non-equilibrium on noise features in the Anderson model.

Findings

Noise suppression at finite frequencies in equilibrium

Noise amplification under non-equilibrium conditions

Sharp peaks related to Kondo temperature at finite voltage

Abstract

We analyze the spectrum of the electric-current autocorrelation function (noise power) in the Anderson impurity model biased by a finite transport voltage. Special emphasis is placed on the interplay of non-equilibrium effects and electron-electron interactions. Analytic results are presented for a perturbation expansion in the interaction strength $U$. Compared to the non-interacting setup we find a suppression of noise for finite frequencies in equilibrium and an amplification in non-equilibrium. Furthermore, we use a diagrammatic resummation scheme to obtain non-perturbative results in the regime of intermediate $U$. At finite voltage, the noise spectrum shows sharp peaks at positions related to the Kondo temperature instead of the voltage.