Quantum Signature Blurred by Disorder in Indirect Exciton Gases

TL;DR

This study investigates the photoluminescence dynamics of indirect excitons in coupled quantum wells at very low temperatures, revealing how exciton interactions influence disorder screening and energy relaxation, but not clearly showing quantum statistical effects.

Contribution

It provides new insights into how exciton-exciton interactions affect disorder screening and energy relaxation in low-temperature quantum well systems.

Findings

Exciton dynamics are strongly correlated with disorder screening.

Energy relaxation shows non-linear characteristics.

Quantum statistical effects like Bose stimulation are not clearly observed.

Abstract

The photoluminescence dynamics of a microscopic gas of indirect excitons trapped in coupled quantum wells is probed at very low bath temperature (approximately 350 mK). Our experiments reveal the non linear energy relaxation characteristics of indirect excitons. Particularly, we observe that the excitons dynamics is strongly correlated with the screening of structural disorder by repulsive exciton-exciton interactions. For our experiments where two-dimensional excitonic states are gradually defined, the distinctive enhancement of the exciton scattering rate towards lowest energy states with increasing density does not reveal unambiguously quantum statistical effects such as Bose stimulation.