Lasing on a narrow transition in a cold thermal strontium ensemble

TLDR: In this article, a Tavis-Cummings model was used to characterize the velocity-dependent dynamics of the atoms as well as the dependency on the cavity detuning, and the authors experimentally and theoretically characterized the lasing threshold and evolution of such a system.

Abstract: Highly stable laser sources based on narrow atomic transitions provide a promising platform for direct generation of stable and accurate optical frequencies. Here we investigate a simple system operating in the high-temperature regime of cold atoms. The interaction between a thermal ensemble of $^{88}\mathrm{Sr}$ at mK temperatures and a medium-finesse cavity produces strong collective coupling and facilitates high atomic coherence, which causes lasing on the dipole forbidden $^{1}S_{0}\ensuremath{\leftrightarrow}^{3}P_{1}$ transition. We experimentally and theoretically characterize the lasing threshold and evolution of such a system and investigate decoherence effects in an unconfined ensemble. We model the system using a Tavis-Cummings model and characterize the velocity-dependent dynamics of the atoms as well as the dependency on the cavity detuning.