Abstract: Diffusion and amplitude dissipation are two major mechanisms of photon field’s evolution, which may be used in quantum controlling and in generating new photon fields. Here two time-evolution equations for diffusion and dissipation from the physical point of view were derived, i.e., the coherent state representation was employed to demonstrate that these two equations’ classical correspondence makes common sense in general. In this way the two equations are reasonable without any doubt. Consequently, it was shown that the dissipation of a binomial state is embodied in its paramenter r0→r0e-2χt,χ is the dissipation coefficient.

Key words: coherent state, density matrix, diffusion equation, attenuation equation