# Nonrenewal statistics in transport through quantum dots

## TL;DR

This paper explores how waiting time correlations in quantum dot transport reveal internal dynamics and noise mechanisms, breaking renewal assumptions and offering new analysis methods for current fluctuations.

## Contribution

It introduces a method to detect waiting time correlations from low-order current correlations, extending analysis to systems without single-electron counting.

## Key findings

- Waiting time correlations reveal internal system dynamics.
- Correlations break renewal theory validity.
- Proposed method infers correlations from low-order current data.

## Abstract

The distribution of waiting times between successive tunneling events is an already established method to characterize current fluctuations in mesoscopic systems. Here, I investigate mechanisms generating correlations between subsequent waiting times in two model systems, a pair of capacitively coupled quantum dots and a single-level dot attached to spin-polarized leads. Waiting time correlations are shown to give an insight into the internal dynamics of the system, for example they allow distinction between different mechanisms of the noise enhancement. Moreover, the presence of correlations breaks the validity of the renewal theory. This increases the number of independent cumulants of current fluctuation statistics, thus providing additional sources of information about the transport mechanism. I also propose a method for inferring the presence of waiting time correlations based on low-order current correlation functions. This method gives a way to extend the analysis of nonrenewal current fluctuations to the systems for which single-electron counting is not experimentally feasible. The experimental relevance of the findings is also discussed, for example reanalysis of previous results concerning transport in quantum dots is suggested.