Bosonic stimulation of cold 1s excitons into a harmonic potential minimum in Cu$_2$O

TL;DR

This study investigates how cold excitons in Cu$_2$O accumulate in a potential well, likely via stimulated scattering, and discusses the potential formation of a Bose-Einstein condensate of paraexcitons.

Contribution

It provides experimental evidence of exciton accumulation due to stimulated scattering and explores the possibility of Bose-Einstein condensation in this system.

Findings

Observation of a spike indicating exciton accumulation at the potential minimum

Evidence suggesting stimulated scattering mediated by acoustic phonons

Discussion on the potential formation of a Bose-Einstein condensate

Abstract

Density distribution of cold exciton clouds generated into a strain-induced potential well by two-photon excitation in Cu$_2$O is studied at 2 K. We find that an anomalous spike, which can be interpreted as accumulation of the excitons into the ground state, emerges at the potential minimum. The accumulation can be due to stimulated scattering of cold excitons, mediated by acoustic phonon emission. Possibility of the formation of the thermodynamic Bose-Einstein condensate of paraexcitons has been discussed.