Disordered Open Plasmonic Cavities for Broadband Emission Enhancement of Nitrogen‐Vacancy Center

Abstract The unique optical and spin properties of nitrogen‐vacancy (NV) centers have revolutionized the possibilities of room‐temperature quantum technologies. However, the applicability of NVs can be further enhanced by coupling them with plasmonic structures. Here, the integration of a few NVs is discussed with disordered open plasmonic cavities made of gold for broadband emission enhancement at room temperature. The study involves a statistical analysis of coupled NVs, revealing accelerated emission rates and enhanced intensity with scalability, long‐term stability, and reproducible emission properties. The disordered open cavities enhance the spontaneous emission decay rate by a factor of five by enhancing the local density of optical states, supported by numerical simulations. The extent of enhancement depends on the spatial variation in nanopore size, affecting mode volume in the proximity of NVs. The statistical variation in the estimated pore size is directly related to the measured lifetime distribution, implying the robustness of the disordered sample over a large area with strong emitter‐cavity coupling. The results are useful to enhance the sensitivity of NV‐based quantum sensors and to realize bright single‐photon sources. The structure is also suitable for many other quantum emitters with slow emission rates and for developing room‐temperature quantum technologies.