Three-dimensional electrical control of the excitonic fine structure for a quantum dot in a cavity

TL;DR

This paper demonstrates a novel three-dimensional electrical control method for the excitonic fine structure in quantum dots embedded in optical cavities, enabling improved quantum light sources.

Contribution

It introduces a new scheme with remote electrical contacts for quantum dots in cavities, allowing precise control and cancellation of fine structure splitting.

Findings

Successful experimental tuning of fine structure splitting.

Reproducible cancellation of the excitonic fine structure.

Numerical simulations confirm three-dimensional electrical control.

Abstract

The excitonic fine structure plays a key role for the quantum light generated by semiconductor quantum dots, both for entangled photon pairs and single photons. Controlling the excitonic fine structure has been demonstrated using electric, magnetic, or strain fields, but not for quantum dots in optical cavities, a key requirement to obtain high source efficiency and near-unity photon indistinguishability. Here, we demonstrate the control of the fine structure splitting for quantum dots embedded in micropillar cavities. We propose a scheme based on remote electrical contacts connected to the pillar cavity through narrow ridges. Numerical simulations show that such a geometry allows for a three-dimensional control of the electrical field. We experimentally demonstrate tuning and reproducible canceling of the fine structure, a crucial step for the reproducibility of quantum light source technology.