Realizing strong light-matter interactions between single nanoparticle plasmons and molecular excitons at ambient conditions

TL;DR

This paper demonstrates strong light-matter interactions between single nanoparticle plasmons and molecular excitons at room temperature, showing potential for quantum optics applications without cryogenic conditions.

Contribution

It provides the first successful demonstration of strong coupling at ambient conditions between single silver nanoprism plasmons and molecular excitons.

Findings

Achieved strong coupling at room temperature.

High coupling figure-of-merit comparable to photonic cavities.

Potential for room-temperature quantum optics applications.

Abstract

Realizing strong light-matter interactions between individual 2-level systems and resonating cavities in atomic and solid state systems opens up possibilities to study optical nonlinearities on a single photon level, which can be useful for future quantum information processing networks. However, these efforts have been hampered by the unfavorable experimental conditions, such as cryogenic temperatures and ultrahigh vacuum, required to study such systems and phenomena. Although several attempts to realize strong light-matter interactions at room-temperature using so-called plasmon resonances have been made, successful realizations on the single nanoparticle level are still lacking. Here, we demonstrate strong coupling between plasmons confined within a single silver nanoprism and excitons in molecular J-aggregates at ambient conditions. Our findings show that the deep subwavelength mode volumes, $V$, together with high quality factors, $Q$, associated with plasmons in the nanoprisms result in strong coupling figure-of-merit -- $Q/\sqrt{V}$ as high as $\sim6\times10^{3}$~$\mu$m$^{-3/2}$ -- a value comparable to state-of-art photonic crystal and microring resonator cavities, thereby suggesting that plasmonic nanocavities and specifically silver nanoprisms can be used for room-temperature quantum optics.