Full counting statistics as a probe of quantum coherence in a side-coupled double quantum dot system

TL;DR

This paper theoretically investigates how high-order current fluctuations in a double quantum dot system reveal quantum coherence, showing that noise characteristics depend on quantum effects and can be tuned for device applications.

Contribution

It introduces a particle-number-resolved master equation approach to analyze full counting statistics, highlighting the role of quantum coherence in noise behavior and device tunability.

Findings

High-order cumulants are more sensitive to quantum coherence than average current.

Quantum coherence influences super-Poissonian noise occurrence depending on coupling regimes.

Super-Poissonian noise can be enhanced by considering electron spins and is tunable via system eigenstates.

Abstract

We study theoretically the full counting statistics of electron transport through side-coupled double quantum dot (QD) based on an efficient particle-number-resolved master equation. It is demonstrated that the high-order cumulants of transport current are more sensitive to the quantum coherence than the average current, which can be used to probe the quantum coherence of the considered double QD system. Especially, the quantum coherence plays a crucial role in determining whether the super-Poissonian noise occurs in the weak inter-dot hopping coupling regime depending on the corresponding dot-lead coupling, and the corresponding values of super-Poissonian noise can be relatively enhanced when considering the spins of conduction electrons. Moreover, this super-Poissonian noise bias range depends on the singly-occupied eigenstates of the system, which thus suggests a tunable super-Poissonian noise device. The occurrence-mechanism of super-Poissonian noise can be understood in terms of the interplay of quantum coherence and effective competition between fast-and-slow transport channels.