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arXiv:2512.01040

Thermalization Rate of Light in Weakly Coupled Molecular Systems

Vladislav Yu. Shishkov

quant-phSubmitted Nov 30, 2025• Announced Dec 2, 2025• 0 citations
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Abstract

Emission and absorption spectra of molecular films are impacted by low-frequency molecular vibrations. These vibrations define the linewidths of the absorption and emission spectral peaks, as well as the Stokes shift. In cavities that use a molecular film as an active medium, low-frequency molecular vibrations facilitate the thermalization of light, enabling the formation of Bose-Einstein condensation. In this work, I employ perturbation theory for Lindblad superoperators and derive the contribution of the low-frequency molecular vibrations to the thermalization rate of light in a weak coupling regime between light and matter. The derived thermalization rate applies for any cavity design but depends on the local microscopic properties of low-frequency molecular vibrations. I provide an estimation for the thermalization rate, which requires only knowledge of the macroscopic parameters of the system: light-matter interaction strength, resonant frequencies of the cavity and excitons, number of molecules in the illuminated area, and the linewidth temperature dependence of the 0-0 peak in the emission spectra of standalone molecular film.

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8 pages

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