Molecular and solid-state topological polaritons induced by population imbalance

TL;DR

This paper presents a theoretical method to optically control the topological properties of exciton-polariton systems in materials by exploiting electronic transition saturation, enabling manipulation of Berry curvature and Chern invariants.

Contribution

It introduces a novel approach to modify topological properties of molecular and solid-state systems using optical pumping and electronic saturation effects.

Findings

Optical control can modify Berry curvature in various materials.

Non-zero Chern invariants can be achieved without forming edge states.

The approach is broadly applicable to optoelectronic materials.

Abstract

Strong coupling between electronic excitations in materials and photon modes results in the formation of polaritons, which display larger nonlinearities than their photonic counterparts due to their material component. We theoretically investigate how to optically control the topological properties of molecular and solid-state exciton-polariton systems by exploiting one such nonlinearity: saturation of electronic transitions. We demonstrate modification of the Berry curvature of three different materials when placed within a Fabry-Perot cavity and pumped with circularly polarized light, illustrating the broad applicability of our scheme. Importantly, while optical pumping leads to non-zero Chern invariants, unidirectional edge states do not emerge in our system as the bulk-boundary correspondence is not applicable. This work demonstrates a versatile approach to control topological properties of novel optoelectronic materials.