Propagator Of A Particle In A Photonic And A Magnetic Field And   Evolution Of A Coherent State
  In the present paper we study the interaction of a photonic field with a particle in a magnetic field. We use formalism similar to the Born-Oppenheimer approximation of molecular physics and we eliminate the photonic field variables by using a method related to the Berry phase to obtain an effective Hamiltonian and then extract the propagator of the particle. As an initial photonic state we assume a coherent one. 
E. G. Thrapsaniotis