Single-Photon Emission From TMDCs through Strong Coupling to EQ Plasmon Modes of an Au Metasurface

In this study, we theoretically demonstrate that a strongly coupled hybrid platform consisting of a compact gold plasmonic metamaterial (metasurface) and a monolayer of transition-metal dichalcogenides (TMDCs) enables scalable single-photon emission (SPE) at room temperature. The Au metasurface is designed to support electric-quadrupole (EQ) resonance that efficiently couples to excitons in tungsten diselenide ( ${\text{WSe}}_2$ ), molybdenum disulfide ( ${\text{MoS}}_2$ ), and molybdenum diselenide ( ${\text{MoSe}}_2$ ). The planar metasurface geometry enables in-plane field overlap with the TMDC exciton, yielding a pronounced coupling strength with a vacuum Rabi splitting exceeding 100 meV. To connect this enhanced coupling to our investigation of SPE purity, we first realized conventional photon blockade (CPB) in an Au- ${\text{WSe}}_2$ hybrid under weak coherent driving, achieving $g^{\left(2\right)}\left(0\right)=4\times 10^{-4}$ . We then demonstrated unconventional photon blockade (UnPB) in Au- ${\text{WSe}}_2$ , Au- ${\text{MoS}}_2$ , and Au- ${\text{MoSe}}_2$ using a two-tone coherent drive to induce destructive interference between two-photon excitation pathways, resulting in very high purity. Additionally, pure dephasing of the emitters up to ${\Gamma }_{\varphi }=40$  meV was considered, and antibunching was preserved. These results establish a scalable route to room-temperature, high-purity SPE for quantum communication and integrated quantum photonics.