# On-Chip Plasmonic Slit-Cavity Platform for Room-Temperature Strong Coupling with Deterministically Positioned Colloidal Quantum Dots

## TL;DR

Researchers developed a compact on-chip platform that enables strong coupling between quantum dots and plasmonic cavities at room temperature.

## Contribution

A deterministic fabrication method for plasmonic slit-cavities with colloidal quantum dots is introduced for room-temperature quantum technologies.

## Key findings

- Photoluminescence-resolved Rabi splitting was observed at room temperature in precharacterized plasmonic cavities.
- Device-to-device variations correlated with the average number of coupled quantum dots.
- Integration of electrodes enabled electrical tuning, though limited by spectral diffusion at room temperature.

## Abstract

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.