Topological Vacuum-Induced Strong Photon–Exciton Coupling

The electromagnetic vacuum construction based on micronano photonic structures is able to engineer the photon–exciton interaction at the single quantum level. Here, through engineering the electromagnetic vacuum formed by edge states, we demonstrate a strong photon–exciton coupling in a topological photonic crystal containing a dielectric nanoantenna. By guiding the scattering photons into the edge states, the linewidth of a nanoantenna with more than hundred nanometers in air can be reduced into only several nanometers due to topological robustness, so that both strong coupling condition and high photon collection efficiency can be achieved. Electromagnetic vacuum under topological protection holds great promise for controlling the light–matter interaction in quantum optics and on-chip quantum information.