Observation of condensed moire exciton polaritons in twisted photonic lattices at room temperature

TL;DR

This study demonstrates strong coupling and moire polariton states in twisted photonic lattices at room temperature, revealing tunable ground and excited states, and exciton polariton condensation.

Contribution

First direct observation of moire polaritons and their states in twisted photonic lattices at room temperature, with tunable distributions and condensation phenomena.

Findings

Observation of staggered moire polariton ground and excited states

Tunable moire polariton distributions in photonic lattices

Realization of exciton polariton condensation at room temperature

Abstract

Moire lattices attract significant attention in double-layer graphene and TMD layer heterostructures as well as in photonic crystals due to the interesting exotic physics that emerges within these structures. However, direct measurement of the moir\'e ground, excited states and Bloch bands in twisted photonic lattices is still illusive. In this work we report strong coupling between excitons in CsPbBr3 microplates and moire photonic modes at room temperature. Depending on the coupling strength between the nearest potential sites, we observe staggered moire polariton ground states, excited states and moire polariton bands. Phase locked moire zero (in-phase) states and moire pi (antiphase) states with different spatial distributions are measured. The moire polariton distribution can be tuned into the shape of a parallelogram by controlling the depth and width of the potential in one photonic lattice with another superimposed one fixed. In addition, moire polaritons in twisted 2D honeycomb lattices are also observed. Increasing the pumping density, we realize exciton polariton condensation in the moire potential sites of the 1D/2D twisted lattices with the coherence time of around 1.4 ps. Our work lays the foundation to study coherent moire polariton condensation in twisted photonic lattices at room temperature.