Resonant Tunneling through Linear Arrays of Quantum Dots

TL;DR

This paper theoretically explores resonant tunneling in linear quantum dot arrays, analyzing effects of electron interactions, localization, and tunnel coupling on current, revealing interference effects that suppress conduction when tunnel rates are high.

Contribution

It introduces a density matrix model for quantum dot arrays considering Coulomb blockade and non-interacting electrons, analyzing current dependence and interference effects.

Findings

Interference suppresses current when tunnel rates are comparable to energy splitting.

Approximation of independent conduction channels fails under certain tunnel rate conditions.

Interaction and localization significantly influence resonant tunneling behavior.

Abstract

We theoretically investigate resonant tunneling through a linear array of quantum dots with subsequent tunnel coupling. We consider two limiting cases: (i) strong Coulomb blockade, where only one extra electron can be present in the array (ii) limit of almost non-interacting electrons. We develop a density matrix description that incorporates the coupling of the dots to reservoirs. We analyze in detail the dependence of the stationary current on the electron energies, tunnel matrix elements and rates, and on the number of dots. We describe interaction and localization effects on the resonant current. We analyze the applicability of the approximation of independent conduction channels. We find that this approximation is not valid when at least one of the tunnel rates to the leads is comparable to the energy splitting of the states in the array. In this case the interference of conduction processes through different channels suppresses the current.