Enhanced thermalization of exciton-polaritons in optically generated potentials

TL;DR

This paper investigates how dimensionality and interactions influence thermalization of exciton-polaritons in optically generated traps, revealing the roles of trapping, density of states, and scattering in their distribution.

Contribution

It demonstrates the impact of trapping and density of states on polariton thermalization and shows efficient polariton-polariton scattering below condensation threshold.

Findings

Significant polariton redistribution due to trapping effects.

Efficient polariton-polariton scattering observed below threshold.

Modification of density of states influences polariton thermalization.

Abstract

Equilibrium Bose-Einstein condensation of exciton-polaritons, demonstrated with a long-lifetime microcavity [Phys. Rev. Lett. 118, 016602 (2017)], has proven that driven-dissipative systems can undergo thermodynamic phase transitions in the limit where the quasiparticle lifetime exceeds the thermalization time. Here, we identify the role of dimensionality and polariton interactions in determining the degree of thermalization in optically generated traps. To distinguish the effect of trapping from interactions and lifetimes, we measured the polariton distribution under four nonresonant Gaussian pumps in a square geometry and compared it with polariton distributions measured with each pump individually. We found that significant redistribution of polaritons arises by trapping and modification of the density of states. Surprisingly efficient polariton-polariton scattering below the condensation threshold is evidenced by the depletion of the inflection-point polaritons. Our work provides a deeper understanding of polariton distributions and their interactions under various geometries of optically generated potentials.