Superradiance and enhanced luminescence from ensembles of a few self-assembled quantum dots

TL;DR

This paper investigates how ensembles of a few coupled quantum dots exhibit superradiance and enhanced luminescence, revealing different photoluminescence decay behaviors under varying excitation conditions.

Contribution

It provides a detailed analysis of PL evolution in homogeneous and inhomogeneous quantum dot ensembles, highlighting the effects of excitation strength on emission dynamics.

Findings

Homogeneous ensembles show superradiant emission under strong excitation.

PL decay is non-exponential under weak excitation in homogeneous ensembles.

Inhomogeneous ensembles exhibit nearly exponential decay with higher rates under weak excitation.

Abstract

We study the evolution of photoluminescence (PL) from homogeneous and inhomogeneous ensembles of a few coupled QDs. We discuss the relation between signals from a given QD ensemble under strong and weak excitation (full inversion and linear response regimes): A system homogeneous enough to manifest superradiant emission when strongly inverted shows a non-exponential decay of the PL signal under spatially coherent weak excitation. In an inhomogeneous ensemble the PL decay is always nearly exponential with a qualitatively different form of the time dependence in the two excitation regimes and with a higher rate under weak excitation.