Theory of Single Photon Control from a Two Level System Source
  Generation of a single photon or a pair of photons from a single emitter is important for quantum information applications. Using the generating function formalism we investigate the theory of a few photons on demand for the square laser pulse and the rapid adiabatic following method. Exact theory and numerical solutions are used to design control fields for a two level emitter, which yield an optimal single or two photon source, under the constrains of finite laser field strength and finite interaction time. Comparison to experiments of Brunel et al, shows that the experiments were made close to optimal conditions. 
Yong He, Eli Barkai