Nonlinear cotunneling through an artificial molecule

TL;DR

This paper investigates electron transport in a double quantum dot system under Coulomb blockade, revealing complex current behavior influenced by bias voltage and inter-dot coupling.

Contribution

It introduces a detailed analysis of cotunneling in coupled quantum dots using a generalized Schrieffer-Wolf transformation and perturbation theory.

Findings

Current exhibits non-monotonic dependence on bias voltage.

Maximum current occurs at weak-to-intermediate inter-dot coupling.

Transport behavior is influenced by internal degrees of freedom.

Abstract

We study electron transport through a system of two lateral quantum dots coupled in series. We consider the case of weak coupling to the leads and a bias point in the Coulomb blockade. After a generalized Schrieffer-Wolf transformation, cotunneling through this system is described using methods from lowest-order perturbation theory. We study the system for arbitrary bias voltages below the Coulomb energy. We observe a rich, non-monotonic behavior of the stationary current depending on the internal degrees of freedom. In particular, it turns out that at fixed transport voltage, the current through the system is largest at weak-to-intermediate inter-dot coupling.