Collective multimode strong coupling in plasmonic nanocavities

TL;DR

This paper demonstrates that off-resonant multimode plasmonic modes significantly influence strong coupling phenomena, revealing a transition from single to collective multimode interactions with implications for quantum technology.

Contribution

It uncovers the crucial role of off-resonant modes in plasmonic nanocavities and characterizes the transition to collective multimode strong coupling.

Findings

Multiple plasmonic modes create numerous oscillation frequencies.

Identification of three coupling regimes: single, multimode, and collective.

Potential for ultra-fast energy transfer in quantum devices.

Abstract

Plasmonic nanocavities enable access to the quantum properties of matter, but are often simplified to single mode models despite their complex multimode structure. Here, we show that off-resonant plasmonic modes in fact play a crucial role in strong coupling, and determine the onset of a novel collective interaction. Our analysis reveals that $n$ strongly coupled plasmonic modes, introduce up to $n(n+1)/2$ oscillation frequencies that depend on their coupling strengths and detunings from the quantum emitter. Furthermore, we identify three distinct regions as the coupling strength increases: (1) single mode, (2) multimode, and (3) collective multimode strong coupling. Our findings enhance the understanding of quantum dynamics in realistic plasmonic environments and demonstrate their potential to achieve ultra-fast energy transfer in light-driven quantum technologies.