sentences:  Thus the dynamics of a two-level atom can be accurately modeled by a photon in an interferometer.It is also possible to model as an atom and a field, and it will, in fact, retain more properties of the system such as lamb shift, but the basic dynamics of resonance fluorescence can be modeled as a spin-1/2 particle.There are several limits that can be analyzed to make the study of resonance fluorescence easier.