Condensation of Excitons in Cu2O at Ultracold Temperatures: Experiment and Theory

TL;DR

This paper reports experimental observations and theoretical analysis of exciton condensation in Cu2O at ultra-low temperatures, highlighting luminescence features indicative of Bose-Einstein condensation.

Contribution

It combines experimental luminescence measurements with theoretical modeling to demonstrate the necessity of including a condensate phase for understanding exciton behavior.

Findings

Observation of a luminescence intensity kink at specific excitation powers

Detection of bimodal spatial luminescence distribution

Evidence supporting Bose-Einstein condensation of excitons

Abstract

We present experiments on the luminescence of excitons confined in a potential trap at milli-Kelvin bath temperatures under cw-excitation. They reveal several distinct features like a kink in the dependence of the total integrated luminescence intensity on excitation laser power and a bimodal distribution of the spatially resolved luminescence. Furthermore, we discuss the present state of the theoretical description of Bose-Einstein condensation of excitons with respect to signatures of a condensate in the luminescence. The comparison of the experimental data with theoretical results with respect to the spatially resolved as well as the integrated luminescence intensity shows the necessity of taking into account a Bose-Einstein condensed excitonic phase in order to understand the behaviour of the trapped excitons.