Mirror-induced effects in cavity polaritonics: Influence on edge states

TL;DR

This paper investigates how cavity mirrors influence edge states and topological properties in cavity polariton systems, revealing effects independent of strong light-matter coupling, including defect-like states and phase transitions.

Contribution

It uncovers boundary-condition effects of cavity mirrors on polariton edge states, demonstrating their role as effective defects and in inducing topological phase transitions.

Findings

Mirrors can act as effective defects creating Tamm edge states.

Transverse mirrors can protect topological edge states.

Parallel mirrors induce topological phase transitions even off-resonance.

Abstract

Optical cavities are widely used to induce strong light-matter coupling and thereby enable the presence of polaritons. While polaritons are at the source of most of the observed physics, the mirrors forming the cavity may also themselves be responsible for a number of phenomena, independently of the strong light-matter coupling regime. Here we use a toy model of a chain of dipolar emitters coupled to a cuboidal cavity. We unveil several effects originating solely from the boundary conditions imposed by the cavity mirrors, that are dominant when the distances of the emitters to the cavity walls are of the order of the interdipole separation. In particular, we show that mirrors in the direction transverse to the chain may act as effective defects, leading to the emergence of Tamm edge states. Considering a topological chain, we demonstrate that such transverse mirrors may also protect edge states against the effects of the strong light-matter coupling. Finally, we find that mirrors parallel to the chain, by the image charges they involve, induce topological phase transitions even in the case of highly off-resonant photons.