Time ordering and counting statistics

TL;DR

This paper investigates the unique time-ordering of current correlators in quantum charge transport, illustrating its importance through models and resolving discrepancies in higher-order cumulant measurements.

Contribution

It introduces an unconventional time-ordering scheme for current correlators and demonstrates its significance in accurately describing quantum charge transport phenomena.

Findings

Current correlators require an unusual time-ordering in quantum transport.

Applying this ordering resolves discrepancies in third cumulant measurements.

The approach clarifies the relation between charge fluctuations and current correlations.

Abstract

The basic quantum mechanical relation between fluctuations of transported charge and current correlators is discussed. It is found that, as a rule, the correlators are to be time-ordered in an unusual way. Instances where the difference with the conventional ordering matters are illustrated by means of a simple scattering model. We apply the results to resolve a discrepancy concerning the third cumulant of charge transport across a quantum point contact.