Controlling the charge environment of single quantum dots in a photonic-crystal cavity

TL;DR

This paper investigates how charge environments influence the optical properties of single quantum dots in photonic-crystal cavities, demonstrating control via electric fields to improve their quantum emission characteristics.

Contribution

It reveals the impact of charge-induced non-resonant coupling and shows how electric fields can suppress this effect, enhancing quantum dot performance in photonic devices.

Findings

Charge environment affects quantum dot emission and coupling.

Electric fields can suppress non-resonant coupling.

Quantum dots can be made closer to ideal two-level systems.

Abstract

We demonstrate that the presence of charge around a semiconductor quantum dot (QD) strongly affects its optical properties and produces non-resonant coupling to the modes of a microcavity. We first show that, besides (multi)exciton lines, a QD generates a spectrally broad emission which efficiently couples to cavity modes. Its temporal dynamics shows that it is related to the Coulomb interaction between the QD (multi)excitons and carriers in the adjacent wetting layer. This mechanism can be suppressed by the application of an electric field, making the QD closer to an ideal two-level system.