Tunneling Effects on Fine-Structure Splitting in Quantum Dot Molecules

TL;DR

This paper theoretically investigates how bias-controlled tunneling in vertically coupled quantum dots affects spin exciton emission, revealing a significant reduction in fine structure splitting that enhances entangled photon-pair generation.

Contribution

It introduces a theoretical model showing bias-controlled tunneling can reduce fine structure splitting without losing optical strength in quantum dot molecules.

Findings

Strongly coupled dots show reduced fine structure splitting.

Reduction in splitting does not decrease optical oscillator strength.

Potential use in entangled photon-pair sources.

Abstract

We theoretically study the effects of bias-controlled interdot tunneling in vertically coupled quantum dots on the emission properties of spin excitons in various bias-controlled tunneling regimes. As a main result, for strongly coupled dots we predict substantial reduction of optical fine structure splitting without any drop in the optical oscillator strength. This special reduction diminishes the distinguibility of polarized decay paths in cascade emission processes suggesting the use of stacked quantum dot molecules as entangled photon-pair sources.