Collective spontaneous emission from a system of quantum dots

TL;DR

This paper investigates spontaneous emission in quantum dot arrays, showing that superradiance effects are similar in regular and random arrangements, and clarifies misconceptions about observing superradiance.

Contribution

It demonstrates that superradiance is not dependent on dot clustering and clarifies that weak excitation emission enhancement does not confirm true superradiance.

Findings

Superradiance occurs similarly in regular and random quantum dot arrangements.

Clustering of dots is not necessary for enhanced emission.

Enhanced emission under weak excitation does not guarantee superradiance.

Abstract

We study the spontaneous emission from a regular lateral array or a randomly distributed ensemble of quantum dots under strong excitation (full inversion) conditions. We focus on the similarities and differences between the cases of random and regular arrangement of the dots and show that there is very little difference between the evolution of luminescence in these two cases, both for identical dots and for a realistically inhomogeneously broadened ensemble. This means that the enhanced emission or superradiance effect is not due to accidental clustering of pairs of dots. Moreover, we point out that observation of an enhanced emission under weak excitation does not prove that true superradiance will develop in a fully inverted system.