Evidence for Stimulated Scattering of Excitons into Microcavity Polaritons

TL;DR

This paper demonstrates stimulated scattering of excitons into microcavity polaritons using a non-equilibrium exciton reservoir, showing stimulation without requiring a Bose-Einstein condensate, through laser-induced polariton populations.

Contribution

It provides experimental evidence of stimulated scattering of excitons into polaritons without the need for a condensate, leveraging non-equilibrium conditions in a semiconductor microcavity.

Findings

Observation of stimulated scattering into polaritons

Use of non-equilibrium exciton reservoir

Laser-induced large polariton populations

Abstract

The wavefunction of a collection of identical quantum particles of integer spin (bosons) is even under exchange of the coordinates of any two of them. This symmetrization rule of quantum mechanics leads to stimulation of the scattering rate into final states whose population is larger than one. For massless photons, it is routinely observed in the laser. For massive bosons, most previous efforts concentrated in realizing the largely populated equilibrium Bose-Einstein condensate, and observing stimulated emission into it. Here we show that we do not need to produce such a condensate to observe final state stimulation. Instead, we take advantage of the highly non-equilibrium exciton reservoir and of the large polariton populations produced by external laser action on a semiconductor microcavity, and measure final state stimulation of the scattering rate of these excitons into the polaritons.