Topological edge states of nonequilibrium polaritons in hollow honeycomb arrays

TL;DR

This paper investigates topological edge states in nonequilibrium polariton condensates within hollow honeycomb arrays, revealing how spin-orbit coupling, Zeeman splitting, and pump tuning influence topological currents and their stability.

Contribution

It introduces the study of topological edge states in finite hollow honeycomb polariton arrays, highlighting the effects of size, interactions, and pump tuning on current behavior.

Findings

Topological currents occur at inner and outer interfaces with opposite directions.

Polariton interactions couple edge states, depending on the hollow size.

Switching of currents is achievable by tuning the pump frequency.

Abstract

We address topological currents in polariton condensates excited by uniform resonant pumps in finite honeycomb arrays of microcavity pillars with a hole in the center. Such currents arise under combined action of the spin-orbit coupling and the Zeeman splitting that break the time-reversal symmetry and open a topological gap in the spectrum of the structure. The most representative feature of this structure is the presence of two interfaces, inner and outer ones, where the directions of topological currents are opposite. Due to the finite size of the structure polariton-polariton interactions lead to the coupling of the edge states at the inner and outer interfaces, which depends on the size of the hollow region. Moreover, switching between currents can be realized by tuning the pump frequency. We illustrate that currents in this finite structure can be stable and study bistability effects arising due to the resonant character of the pump.