Interacting multi-component exciton gases in a potential trap: phase separation and Bose-Einstein condensation

TL;DR

This paper investigates a multi-component exciton gas in a potential trap, analyzing how Bose-Einstein condensation and inter-component interactions influence the optical emission spectrum and lead to phase separation.

Contribution

It provides a detailed theoretical analysis of the spectral signatures of BEC and phase separation in interacting multi-component exciton gases in a trap.

Findings

Bose-Einstein condensation alters the emission spectrum distinctly.

Interactions cause phase separation depending on temperature and particle number.

Spectral features reflect the chemical potential and quasiparticle spectrum renormalization.

Abstract

The system under consideration is a multi-component gas of interacting para- and orthoexcitons confined in a three dimensional potential trap. We calculate the spatially resolved optical emission spectrum due to interband transitions involving weak direct and phonon mediated exciton-photon interactions. For each component, the occurrence of a Bose-Einstein condensate changes the spectrum in a characteristic way so that it directly reflects the constant chemical potential of the excitons and the renormalization of the quasiparticle excitation spectrum. Moreover, the interaction between the components leads, in dependence on temperature and particle number, to modifications of the spectra indicating phase separation of the subsystems. Typical examples of density profiles and luminescence spectra of ground-state para- and orthoexcitons in cuprous oxide are given.