Coherent Radiation in Atomic Systems

Over the last century, quantum mechanics has dramatically altered our understanding of light and matter. Impressively, exploring the relationship between the two continues to provide important insights into the physics of many-body systems. In this thesis, we add to this still growing field of study. Specifically, we discuss superradiant line-broadening and cooperative dipole-dipole interactions for cold atom clouds in the linear-optics regime. We then discuss how coherent radiation changes both the photon scattering properties and the excitation distribution of atomic arrays. After that, we explore the nature of superradiance in initially inverted clouds of multi-level atoms. Finally, we explore the physics of clouds with degenerate Zeeman ground states, and show that this creates quantum effects that fundamentally change the photon scattering of atomic ensembles