Photon-exciton strong coupling induced by topological edge state

Strong coupling between single quantum emitter and dielectric nanoparticle has not been achieved due to large scattering loss of dielectric nanoparticle. Here we propose strong photon-exciton coupling mechanism under topological protection. In hybrid two-dimensional topological photonic crystal structure containing gap dielectric nanoantenna, owing to the robustness of the topological pattern, the photons originally scattered to the surrounding area can be guided into the edge-state channel, so the linewidth of nanoantenna is greatly narrowed. Simultaneously, the stronger local field in the nanoantenna gap provides a relatively large coupling coefficient. Therefore, strong coupling condition is achieved. Our results demonstrate the potential of dielectric structures as a platform for studying cavity quantum electrodynamics in a single quantum level.