Quantum Droplets of Light in Semiconductor Microcavities

TL;DR

This paper predicts the formation of quantum droplets of light in semiconductor microcavities, revealing a new phase of polaritons that could enable lower-threshold condensation and advance quantum polaritonic research.

Contribution

It introduces the concept of quantum droplets in solid-state polariton systems, extending the phenomenon from atomic gases to semiconductor microcavities with tunable interactions.

Findings

Quantum droplets can form in exciton-polariton systems with realistic parameters.

Detection methods include analyzing excitation spectrum and spatial profile.

Potential for lower-threshold polariton condensation and new quantum regimes.

Abstract

Quantum droplets are dilute self-bound configurations of bosons that result from the balance between a mean-field attraction and a repulsion induced by quantum fluctuations. Such droplets have been successfully realized in cold atomic gases and represent a signature of their quantum nature. Here, we predict the existence of a similar droplet phase in a solid-state system, involving polaritons formed from the strong coupling between excitons (bound electron-hole pairs) and photons in a semiconductor microcavity. We consider a spin mixture of exciton-polaritons near a biexciton Feshbach resonance, which allows one to tune the interspecies interactions to be attractive and comparable in magnitude to the intraspecies repulsion. We find that self-bound quantum droplets are achievable for realistic parameters in atomically thin semiconductors, and that they can be detected via their excitation spectrum and spatial profile. This exotic phase could potentially lead to polariton condensation at lower thresholds and it opens an alternative avenue to achieve the long-sought quantum polaritonic regime.