Coherence Properties of a Radiation Field in the Dicke Model Hamiltonian
Michiyoshi Nagashima · Journal of the Physical Society of Japan · 1978
A normalized variance of a radiation field is introduced to study the coherence properties of spontaneous and induced emissions in the Dicke model Hamiltonian. It is shown that a superradiant emission from an atomic Dicke state cannot be in a coherent state, though the Dicke state emits photons in a Poisson distribution for the photon number. In the case of the induced omission for an initially intense coherent radiation field, the time evolution of the normalized variance is calculated to see to what extent the initially coherent state remains coherent. We obtain the time evolution of the expectation values of the atomic operators and the photon number operator. These solutions are then compared with semi-classical solutions obtained by taking the diagonal coherent state representation.