Radiative thermalization in semiclassical simulations of light-matter interaction

Esteban D. Gadea, Carlos M. Bustamante , Tchavdar N. Todorov, Damian A. Scherlis

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5 Citations (Scopus)
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Prediction of the equilibrium populations in quantum dynamics simulations of molecules exposed to black-body radiation has proved challenging for semiclassical treatments, with the usual Ehren- fest and Maxwell-Bloch methods exhibiting serious failures. In this context, we explore the behavior of a recently introduced semiclassical model of light-matter interaction derived from a dissipative Lagrangian [Phys. Rev. Lett. 126, 087401 (2021)]. It is shown that this model reproduces the Boltzmann populations for two-level systems, predicting the black-body spectra in approximate agreement with Planck’s distribution. In multilevel systems, small deviations from the expected oc- cupations are seen beyond the first excited level. By averaging over fast oscillations, a rate equation is derived from the dissipative equation of motion that makes it possible to rationalize these devi- ations. Importantly, it enables us to conclude that this model will produce the correct equilibrium populations provided the occupations of the lowest levels remain close to unity, a condition satisfied at low temperature or small excitations.
Original languageEnglish
Article number042201
JournalPhysical Review A (Atomic, Molecular, and Optical Physics)
Publication statusPublished - 01 Apr 2022


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