Enhanced shot noise in asymmetric interacting two level systems

TL;DR

This paper investigates how interactions in a two-level electronic system influence shot noise, revealing conditions where cotunneling significantly enhances noise despite sequential tunneling dominating current flow.

Contribution

It introduces a detailed analysis of shot noise in an asymmetric two-level system, highlighting the impact of interactions and cotunneling processes on noise characteristics.

Findings

Shot noise is enhanced by interactions.

Fano factor depends on coupling properties.

Cotunneling significantly affects noise under certain conditions.

Abstract

We study a model of two interacting levels that are attached to two electronic leads, where one of the levels is attached very weakly to the leads. We use rate equations method to calculate the average current and the noise of electrons transmitted through the two levels. We show that the shot noise is enhanced due to the interactions and that the Fano factor depends on the properties of the couplings between the levels and the leads. We study both sequential tunneling and cotunneling processes and show that there is a range of parameters in which the cotunneling processes affect the noise significantly, even though most of the current is carried by sequential tunneling processes.