Dynamical correlations in electronic transport through a system of coupled quantum dots

TL;DR

This paper investigates how Coulomb interactions influence current correlations in coupled quantum dots, revealing non-monotonic bias dependence and the role of charge drag effects in electron transport.

Contribution

It provides a detailed analysis of dynamical correlations and shot noise in coupled quantum dots, highlighting the impact of Coulomb interaction and inter-dot coupling strength.

Findings

Cross-correlations are generally negative and non-monotonic with bias voltage.

Strong inter-dot coupling leads to correlated electron transfer and charge drag.

Local potential fluctuations mimic Pauli exclusion effects.

Abstract

Current auto- and cross-correlations are studied in a system of two capacitively coupled quantum dots. We are interested in a role of Coulomb interaction in dynamical correlations, which occur outside the Coulomb blockade region (for high bias). After decomposition of the current correlation functions into contributions between individual tunneling events, we can show which of them are relevant and lead to sub-/supper-Poissonian shot noise and negative/positive cross-correlations. The results are differentiated for a weak and strong inter-dot coupling. Interesting results are for the strong coupling case when electron transfer in one of the channel is strongly correlated with charge drag in the second channel. We show that cross-correlations are non-monotonic functions of bias voltage and they are in general negative (except some cases with asymmetric tunnel resistances). This is effect of local potential fluctuations correlated by Coulomb interaction, which mimics the Pauli exclusion principle.