Moir\'e-Polaritons in a Dark Bose-Einstein Condensate

TL;DR

This paper explores the interaction of moiré polaritons with a dark-state exciton Bose-Einstein condensate, revealing significant energy shifts and new bound states due to strong exciton interactions.

Contribution

It introduces a variational method to analyze moiré polaritons in a dark exciton condensate, highlighting the impact of exciton interactions on polariton properties.

Findings

Strong exciton interactions cause sizable energy shifts.

Emergence of a stable, repulsive-polariton bound state.

Modification of the polariton energy spectrum.

Abstract

Quantum mixtures of moir\'e excitons have arisen as a platform for realizing novel phases of light and matter. Here, we study moir\'e polaritons coupled to a Bose-Einstein condensate of dark-state excitons confined to a moir\'e superlattice. We develop a variational approach to analyze the optical response of the system and demonstrate that strong exciton-exciton interactions significantly modify the character of moir\'e polaritons, leading to sizable energy shifts of the avoided crossing between the principal polariton branches, and the emergence of an additional, stable repulsive-polariton bound state.