Shot noise in electron transport through a double quantum dot: A master equation approach

TL;DR

This paper compares two master equation approaches for analyzing shot noise in electron transport through a double quantum dot, highlighting the validity range and experimental relevance of the eigenstate basis method.

Contribution

It introduces and compares occupation-state and eigenstate basis master equations, showing the latter's broader validity and better experimental agreement.

Findings

Eigenstate basis approach remains valid for arbitrary interdot coupling.

Significant differences in current and shot noise predictions when interdot coupling is large.

Eigenstate basis results align qualitatively with recent experimental observations.

Abstract

We study shot noise in tunneling current through a double quantum dot connected to two electric leads. We derive two master equations in the occupation-state basis and the eigenstate basis to describe the electron dynamics. The approach based on the occupation-state basis, despite widely used in many previous studies, is valid only when the interdot coupling strength is much smaller than the energy difference between the two dots. In contrast, the calculations using the eigenstate basis are valid for an arbitrary interdot coupling. We show that the master equation in the occupation-state basis includes only the low-order terms with respect to the interdot coupling compared with the more accurate master equation in the eigenstate basis. Using realistic model parameters, we demonstrate that the predicted currents and shot-noise properties from the two approaches are significantly different when the interdot coupling is not small. Furthermore, properties of the shot noise predicted using the eigenstate basis successfully reproduce qualitative features found in a recent experiment.