Numerical simulations of atomic decay in cavities and material media

Starting from first principles we simulate numerically the dynamics of a sy stem of two-level atoms interacting with a multimode electromagnetic field in a one-dimensional cavity. in particular, we investigate the spontaneous emission of an excited two-level atom in the cavity. We show how the decay depends on the mode spectrum and on the position of the atom in the cavity. We study how the spontaneous emission is modified when the initially excit ed atom is surrounded by a material medium modeled as a system of two-level atoms. We also study the propagation of photon wave packets emitted by the atom within the material media. Our microscopic model provides us with a d eeper understanding of the atom-field interaction and offers us a framework for a systematic investigation of the transition from a microscopic to a m acroscopic (phenomenological) description of the spontaneous decay in mater ial media (e.g.. dielectrics).