Pre-Submission Thesis Presentation

The coherent interaction between the quantized cavity field and a driven atomic ensemble forms a coupled quantum system whose dynamics arise from a balance between energy exchange and dissipation. This interplay, leads to rich phenomena with broad relevance in light-matter physics. Such systems are considered to be in the strong coupling regime when coherent atom–cavity interaction exceeds dissipation, and in the weak coupling regime when dissipative rates dominate.

This thesis investigates interactions between driven ultracold 85Rb atoms in a magneto-optical trap (MOT) and a moderate-finesse optical Fabry-Perot cavity, focusing on the intermediate regime where even though the single-atom cavity coupling is weak, collective interactions enable strong coupling effects. By tuning the drive-laser conditions and atom–cavity detuning, the system generates self-sustained cavity emission arising from Mollow gain and coherent scattering, despite having no direct input light. Apart from readily measurable mode properties, critical information for the atom-light-cavity system is obtained by studying the intensity-intensity correlation (g(2)) of the cavity emitted field. The experimental work describes the setup design, including MOT operation, cavity stabilization and systematic calibration of the g(2) measurement system to eliminate artifacts from detector dark counts and intensity fluctuations. Key findings include an intriguing oscillatory g(2) behavior with fast and slow frequency components that vary with atom-cavity detuning. The two frequencies components can be largely isolated by polarization selection, indicating polarization-decoupled photon transfer pathways between the drive field and the cavity field. These results open avenues toward generation of non-classical light, studying cavity mediated mechanical effects on atomic ensembles, and testing light-matter interactions in unexplored regimes. In addition, the work also establishes techniques for minimally destructive detection of open quantum systems.