On-Chip Plasmonic Slit-Cavity Platform for Room-Temperature Strong Coupling with Deterministically Positioned...

Strong coupling between quantum emitters and optical cavities underpins many quantum photonic technologies, yet achieving this regime at room temperature in compact, deterministic on-chip platforms remains challenging due to the difficulty of fabricating cavities with ultrasmall mode volumes and precisely positioning quantum emitters. Here, we demonstrate a robust quantum plasmonic device in which colloidal quantum dots are strongly coupled to plasmonic slit cavities. Our dielectrophoresis-based positioning technique with real-time photoluminescence feedback enables parallel device fabrication and straightforward integration with additional optical elements, such as waveguides. Our measurements reveal clear photoluminescence-resolved Rabi splitting at room temperature in precharacterized cavities, with device-to-device variations scaling with the average number of coupled quantum dots. While electrical tuning via the quantum-confined Stark effect is enabled by integrated electrodes, its impact is largely overshadowed by room-temperature spectral diffusion. These results establish a scalable and electrically addressable plasmonic platform for room-temperature quantum technologies.