Exciton-polaritons gas as a nonequilibrium coolant

TL;DR

This paper demonstrates that resonantly excited exciton-polariton fluids can act as efficient nonequilibrium coolants in semiconductor microcavities, revealing an ultrafast cooling mechanism that surpasses traditional thermal limits.

Contribution

It introduces a novel optical method to measure and analyze nonequilibrium cooling via exciton-polaritons, showing enhanced heat removal capabilities at low temperatures.

Findings

Maximum cooling power observed at 50K and below.

Identification of an ultrafast cooling mechanism.

Each scattering event removes more heat than in equilibrium conditions.

Abstract

Using angle-resolved Raman spectroscopy, we show that a resonantly excited ground-state exciton-polariton fluid behaves like a nonequilibrium coolant for its host solid-state semiconductor microcavity. With this optical technique, we obtain a detailed measurement of the thermal fluxes generated by the pumped polaritons. We thus find a maximum cooling power for a cryostat temperature of $50$K and below where optical cooling is usually suppressed, and we identify the participation of an ultrafast cooling mechanism. We also show that the nonequilibrium character of polaritons constitutes an unexpected resource: each scattering event can remove more heat from the solid than would be normally allowed using a thermal fluid with normal internal equilibration.