Collective light-matter interaction in plasmonic waveguide quantum electrodynamics

TL;DR

This paper explores the collective interaction between light and matter in plasmonic waveguides, revealing new hybridized states, decay regimes, and quantum effects through theoretical analysis.

Contribution

It introduces the concept of a hybridized plasmon-polariton formed by a timed-Dicke state coupled to a surface-plasmon mode, demonstrating novel collective light-matter interactions.

Findings

Identification of a hybridized plasmon-polariton with directional properties.

Observation of normal-mode splitting indicating weak and strong coupling regimes.

Detection of three distinct decay regimes and quantum vacuum effects in emission spectra.

Abstract

Rabi oscillations characterize light-matter hybridization in the waveguide quantum electrodynamics~(WQED) framework, with their associated decay rates reflecting excitation damping, yet their behavior remains unresolved when collective emitters are coupled to a collective waveguide mode. This scenario reveals a conceptually novel collective-light-collective-matter interaction, realizable when a timed-Dicke state~(TDS) of subwavelength emitters couples to a slow, delocalized surface-plasmon mode, forming a hybridized plasmon-polariton~(HPP). The HPP acquires its directionality from the TDS via momentum matching. It also exhibits plasmonic characteristics, with excitation frequencies following the surface-plasmon dispersion relation. We obtain a Rabi oscillation and a long-time decay that describe the HPP and use them to reveal weak- and strong-coupling regimes through the emergence of normal-mode splitting. By performing a finite-time Lyapunov-exponent analysis, we show that the HPP also exhibits instantaneous decay and identify three distinct decay regimes: early-time rapid, transient-time oscillatory, and long-time classical. Finally, by analyzing the emission spectrum, we observe an anticrossing of the peak doublets~(a feature also seen in cavity QED setups) which originates from quantum vacuum effects and the resulting non-Markovian HPP evolution in our WQED.