Theory of nonlinear optical response of ensembles of double quantum dots

TL;DR

This paper presents a theoretical analysis of the nonlinear optical response of double quantum dot ensembles, revealing how interdot coupling influences collective radiative decay and enables observation of super- and subradiant effects even with energy mismatches.

Contribution

It introduces a theoretical framework for understanding the nonlinear optical response of coupled quantum dot pairs, highlighting the role of interdot coupling in collective radiative phenomena.

Findings

Resonant pairs dominate short-delay FWM response, revealing interdot coupling.

Long-delay decay shows two rates linked to super- and subradiance.

Coupling enhances collective effects despite energy mismatches.

Abstract

We study theoretically the time-resolved four-wave mixing (FWM) response of an ensemble of pairs of quantum dots undergoing radiative recombination. At short (picosecond) delay times, the response signal shows beats that may be dominated by the subensemble of resonant pairs, which gives access to the information on the interdot coupling. At longer delay times, the decay of the FWM signal is governed by two rates which result from the collective interaction between the two dots and the radiation modes. The two rates correspond to the subradiant and super-radiant components in the radiative decay. Coupling between the dots enhances the collective effects and makes them observable even when the average energy mismatch between the dots is relatively large.