Complex plasmon-exciton dynamics revealed through quantum dot light emission in a nanocavity

TL;DR

This study investigates the complex interactions between quantum dots and plasmonic nanocavities, revealing strong coupling, non-classical emission, and dark state involvement through experimental measurements and theoretical modeling.

Contribution

It provides new insights into plasmon-exciton interactions at the single or few-emitter level, highlighting the role of dark states in quantum dynamics within nanocavities.

Findings

Observation of Rabi splitting indicating near-strong coupling

Detection of non-classical light emission from quantum dots

Identification of dark state contributions in emission spectra

Abstract

Plasmonic cavities can confine electromagnetic radiation to deep sub-wavelength regimes. This facilitates strong coupling phenomena to be observed at the limit of individual quantum emitters. Here we report an extensive set of measurements of plasmonic cavities hosting one to a few semiconductor quantum dots. Scattering spectra show Rabi splitting, demonstrating that these devices are close to the strong coupling regime. Using Hanbury Brown and Twiss interferometry, we observe non-classical emission, allowing us to directly determine the number of emitters in each device. Surprising features in photoluminescence spectra point to the contribution of multiple excited states. Using model simulations based on an extended Jaynes Cummings Hamiltonian, we find that the involvement of a dark state of the quantum dots explains the experimental findings. The coupling of quantum emitters to plasmonic cavities thus exposes complex relaxation pathways and emerges as an unconventional means to control dynamics of quantum states.