Modeling of blackbody-radiation-induced decoherence in Rydberg atom sensor and validation against probe absorption measurements

We present a first-principles density-matrix simulation of blackbody-radiation (BBR)-induced decoherence in cesium Rydberg electromagnetically induced transparency (EIT). The model incorporates spontaneous emission, blackbody-stimulated transitions, collisional broadening, transit-time-limited decoherence, and Doppler averaging across a truncated but converged Rydberg manifold within a Lindblad masterequation framework. From the steady-state solution, we extract both the temperaturedependent Rydberg coherence decay rate and the corresponding probe absorption coefficient.We show that the experimentally observed modification of probe transmission reported by Kaur et al. (2026) arises predominantly from BBR-induced decoherence of the Rydberg coherence, rather than from population redistribution among Rydberg levels. The model reproduces the observed temperature-dependent trends in probe absorption with quantitative accuracy. By employing a fully m j -resolved transition network, we establish a direct connection between microscopic decoherence processes and macroscopic optical observables. The decoherence effect on the optical response is sufficiently well-defined to serve as a measurable signal, enabling potential applications in Rydberg-based thermometry and radiometry.These results provide a self-consistent microscopic description of BBR-limited performance in thermal-vapor Rydberg EIT and establish a quantitative link between Rydberg-state decoherence and measurable changes in optical susceptibility, with direct relevance to RF-based sensing platforms.