To support experiments, we are modelling the passage of laser beams through systems such as warm atomic vapors and rare-earth-doped crystals.   The equations include both the time-evolution of individual atoms or ions as well as the electromagnetic fields with which they interact.   The EM fields may be modelled as either classical or quantized depending on the problem.  A quantized formulation is ultimately necessary for entangled-pair generation.   Research goals include high rate of entangled-pair generation as well as fidelity of quantum memory.