Pattern formation of indirect excitons in coupled quantum wells

TL;DR

This paper models the spatial distribution of indirect excitons in coupled quantum wells using a nonlinear Schrödinger equation, explaining experimental phenomena and predicting complex patterns at higher densities.

Contribution

It introduces a nonlinear Schrödinger model with specific interactions to interpret and predict exciton pattern formations in quantum wells.

Findings

Explains the contraction and expansion of exciton clouds with increasing exciton number.

Reconciles observed exciton ring patterns from previous experiments.

Predicts richer exciton patterns at higher densities for future testing.

Abstract

Using a nonlinear Schr\"odinger equation including short-range two-body attraction and three-body repulsion, we investigate the spatial distribution of indirect excitons in semiconductor coupled quantum wells. The results obtained can interpret the experimental phenomenon that annular exciton cloud first contracts then expands when the number of confined excitons is increased in impurity potential well, as observed by Lai \emph{et al.} [Lai $et al.$, Science \textbf{303}, 503 (2004)]. In particular, the model reconciles the patterns of exciton rings reported by Butov \emph{et al.} [Butov $et al.$, Nature \textbf{418}, 751 (2002)]. At higher densities, the model predicts much richer patterns, which could be tested by future experiments.