Molecular spectra in collective Dicke states

TL;DR

This paper investigates how interactions among many two-level systems in a microcavity can suppress decoherence effects, leading to distinctive spectral features such as level shifts and reduced vibrational satellites.

Contribution

It introduces a model showing that collective interactions can significantly mitigate decoherence in large ensembles of TLSs, with specific spectral signatures.

Findings

Strong $oxed{ ext{O}(\sqrt{N})}$ level shifts observed

Decoherence width suppressed by $1/N$

Vibrational satellites reduced proportionally to $1/N$

Abstract

We study a model describing competition of interactions between $N$ two-level systems (TLSs) against decoherence. We apply it to analyze dye molecules in an optical microcavity, where molecular vibrations provide a local source for decoherence. Most interesting is the case when decoherence strongly affects each individual TLS, e.g. via broadening of emission lines as well as vibrational satellites, however its influence is strongly suppressed for large $N$ due to the interactions between TLSs. In this interaction dominated regime we find unique signatures in the emission spectrum, including strong $\mathcal{O}(\sqrt{N})$ level shifts, as well as $1/N$ suppression of both the decoherence width and of the vibrational satellites.