We study spatially indirect excitons of GaAs quantum wells, confined in a 10 microns electrostatic trap. Below a critical temperature of about 1 Kelvin, we detect macroscopic spatial coherence and quantised vortices in the weak photoluminescence emitted from the trap. These quantum signatures are restricted to a narrow range of density, in a dilute regime. They manifest the formation of a four-component superfluid, made by a low population of optically bright excitons coherently coupled to a dominant fraction of optically dark excitons.
@article{arxiv.1606.04755,
title = {Quantized Vortices and Four-Component Superfluidity of Semiconductor Excitons},
author = {Romain Anankine and Mussie Beian and Suzanne Dang and Mathieu Alloing and Edmond Cambril and Kamel Merghem and Carmen Gomez Carbonell and Aristide Lemaitre and Francois Dubin},
journal= {arXiv preprint arXiv:1606.04755},
year = {2017}
}