Current-voltage correlations in interferometers

TL;DR

This paper explores current-voltage correlations in quantum interferometers, developing a stochastic path integral approach to analyze fluctuations and distributions at probes, revealing differences between voltage and occupation number fluctuations.

Contribution

It introduces a stochastic path integral method for higher order fluctuation analysis and compares voltage and occupation number distributions in interferometers.

Findings

Voltage and occupation number fluctuation distributions differ significantly.

The generating functions for current cumulants are identical for certain probes.

Occupation number fluctuations are broader than voltage fluctuations.

Abstract

We investigate correlations of current at contacts and voltage fluctuations at voltage probes coupled to interferometers. The results are compared with correlations of current and occupation number fluctuations at dephasing probes. We use a quantum Langevin approach for the average quantities and their fluctuations. For higher order correlations we develop a stochastic path integral approach and find the generating functions of voltage or occupation number fluctuations. We also derive a generating function for the joint distribution of voltage or occupation number at the probe and current fluctuations at a terminal of a conductor. For energy independent scattering we found earlier that the generating function of current cumulants in interferometers with a one-channel dephasing or voltage probe are identical. Nevertheless, the distribution function for voltage and the distribution function for occupation number fluctuations differ, the latter being broader than that of former in all examples considered here.