Polariton condensation with saturable molecules dressed by vibrational modes

TL;DR

This paper investigates how vibrational modes in organic molecules affect polariton condensation, revealing phenomena like re-entrance and first-order transitions in a modified Tavis-Cummings model.

Contribution

It introduces a theoretical model incorporating vibrational dressing of molecules, predicting new phase behaviors in polariton condensation.

Findings

Vibrational modes can induce re-entrant phase transitions.

Coupling to vibrational modes can make the condensation transition first order.

The model predicts a complex phase diagram with novel features.

Abstract

Polaritons, mixed light-matter quasiparticles, undergo a transition to a condensed, macroscopically coherent state at low temperatures or high densities. Recent experiments show that coupling light to organic molecules inside a microcavity allows condensation at room temperature. The molecules act as saturable absorbers with transitions dressed by molecular vibrational modes. Motivated by this we calculate the phase diagram and spectrum of a modified Tavis-Cummings model, describing vibrationally dressed two-level systems, coupled to a cavity mode. Coupling to vibrational modes can induce re-entrance, i.e. a normal-condensed-normal sequence with decreasing temperature and can drive the transition first order.