The entropy exchange between a tow-level atom and a single-mode radiation field is studies in a damped system.The results show that there is an entropy exchange phenomenon between atom and field. Especially, it is prove that there is a condition for entropy exchange between atom and damped field.
The time evolution of linear entropy of atom-field coupling system, atom and field in the system of two two-level atoms inside a single-mode cavity with amplitude-damping under the condition of large detuning were investigated. The effects of the initial preparation of two atoms, the decay rate of cavity field and the mean photon number of field on all kinds of linear entropy were discussed. The results show that if both the two atoms are in their excited states or ground states, all the linear entropies equal to zero. But when the two atoms are in their coherent superposition state of excited state and ground state, the cavity dissipation will lead to the system to evolve into a mixed state, the linear entropy of atom and field exhibits periodic oscillations with damped amplitude.
The quantum mechanical analysis for a non-resonant case of a single radiation mode interacting with a two-level atom in a cavity is studied. Expressions for the mean value of photon number and the time evolution of the atomic motion are given. The frequency of exchange energy between the atomic levels and the radiation field systems for non- resonant and resonant interactions is obtained. Results for all initial states of the atom-radiation field are presented. Results for resonant and non-resonant interactions are compared.
Considering a moving two-level atom interacting with a single-mode thermal field through multi-photon process, in this paper we study the entropy exchange between the atom and the field by using quantum partial entropy and entanglement measured by using Concurrence, and investigate the effects of the initial atomic state, the atomic motion, the mean photon number and the transition photon number on entropy and entanglement. The results show that the entropy exchange and the entanglement exhibit the periodic evolution due to atomic motion, and entropy exchange occurs. The entanglement between the atom and the field is strengthened as the transition photon number increases. When the partial entropy exchange between atom and field is zero, the entanglement is also zero.