From quantum computation to communication, design of quantum devices and peripheral technology relies strongly on the interaction of light with matter. This requires not only modelling these interactions at the microscopic level but also seeking appropriate solutions at different operational regime. In this talk, we informally look at a few approaches that can be used to study such light-matter interactions. These range from rate equations, cluster expansion and quantum trajectories to study condensates of light to tensor-network methods to design spin-ensemble based quantum memories.
