Temporal dynamics of photons in an optically thin cloud of cold atoms

Cold atoms have become an indispensable tool in quantum computing by utilizing carefully tuned lasers and magnetic fields. They play a crucial role in advancing our understanding of atom-photon interactions and serve as platforms for various applications such as precision spectroscopy, atomic clocks, quantum simulations, sensing and computing amongst others. Investigating the dynamics of atom-photon systems, particularly in scenarios involving studying atomic decay in cold atoms ensemble helps refine our understanding of quantum coherence and its role in many-body physics. We study the temporal dynamics of the decay of photons using an optically thin sample of 10⁴ cold ¹³³Cs atoms after their controlled release from a magneto-optical trap (MOT). A short excitation laser pulse is sent through the atomic cloud, driving the transition |6S_1/2, F=3〉→|6P_3/2, F'=4〉. We detect the resulting fluorescence in an orthogonal direction using a microscope objective with 0.4 NA and a single photon counting module (SPCM). In this work, we study the interplay between atom-photon interactions in the quantum system and report the observed decay of photons in the cold atomic medium. The observed decay time is larger than the transition's natural decay time. These findings pave the way for studying subradiance and diffusion in atom-photon interactions, enabling high-fidelity quantum state preparation, manipulation, and readout for quantum information processing applications.