On chip plasmonic slit cavity platform for room temperature strong coupling with deterministically positioned colloidal quantum dots

TL;DR

This paper presents a scalable on-chip plasmonic platform where colloidal quantum dots are deterministically coupled to slit cavities at room temperature, enabling strong light-matter interactions for quantum photonics.

Contribution

It introduces a dielectrophoresis-based positioning technique with real-time feedback for deterministic coupling of quantum dots to plasmonic cavities on-chip.

Findings

Clear Rabi splitting observed at room temperature.

Coupling strength varies with the number of quantum dots.

Electrical tuning is possible but limited by spectral diffusion.

Abstract

Strong coupling between quantum emitters and optical cavities is essential for quantum information processing, high-purity single-photon sources, and nonlinear quantum devices. Achieving this regime at room temperature in a compact, deterministic on-chip platform-critical for integration with nanoelectronic circuitry and scalable device architectures-remains a major challenge, mainly due to the difficulty of fabricating cavities with ultra-small mode volumes and precisely positioning quantum emitters. Here, we demonstrate a robust quantum plasmonic device in which colloidal quantum dots (Qdots) are strongly coupled to plasmonic slit cavities using a dielectrophoresis-based positioning technique with real-time photoluminescence (PL) feedback, providing directly resolvable coupled structures that enable parallel device fabrication and straightforward integration with additional optical elements such as waveguides. Our measurements reveal clear PL resolved Rabi splitting at room temperature with pre characterized cavities, with variations across devices that scale with the average number of coupled Qdots. While electrical tuning via the quantum-confined Stark effect is enabled by integrated electrodes, its impact is largely overshadowed by room-temperature spectral diffusion. Our results pave the way for scalable, electrically tunable quantum plasmonic platforms, offering new opportunities for integrated quantum photonic circuits, active light-matter interactions, and room-temperature quantum technologies.