Current fluctuations in a single tunnel junction

TL;DR

This paper investigates the noise spectra of currents in a single tunnel junction, considering interaction effects and environmental influences, revealing differences between local and lead-measured fluctuations with implications for experiments.

Contribution

It introduces an effective capacitance model to incorporate interaction effects and environmental influences into the analysis of current noise spectra in tunnel junctions.

Findings

Local and lead-measured fluctuations have different noise spectra.

Charging energy and environment significantly affect noise characteristics.

The relation between different fluctuation measurements is complex and nontrivial.

Abstract

We study noise spectra of currents through a tunnel junction in weak tunneling limit. We introduce effective capacitance to take into account the interaction effect and explicitly incorporate the electromagnetic environment of the junction into the formulation. We study the effect of charging energy and macroscopic environment on noise spectra. We calculate current fluctuations at tunneling barrier and fluctuations measured at leads. It is shown that two fluctuations have different noise spectra and the relation between them is nontrivial. We provide an explanation for the origin of the difference. Experimental implications are discussed.