Light Field Entropy Dynamics, Interaction With The Three-level Atom

In 1989,the entropy theory has been applied to quantum optics by Phoenix and Knight, they have shown the entropy theory is a convenient and sensitive measure of the information concerning and evolution about interaction of the field with the atom. Entropy not only is a very useful operational measureof the purity of the quantum state,which automatically includes all moments of the density operator,but is applied to describe the degree of entanglement in quantum system,so has a intensive use in quantum information.On the other hand,the study on the properties of the entanglement between the field and the atom will have a entensive use in performing quantum state about the field and the atom and the field and atom of quantum information and computing.Much study has been done on entropic dynamics in the JCM and all kinds of generalized JCM,since 15 years recently.But,at present a trait of these study work in commom is: (i) the atom-field coupling coefficients is simply regarded to a constant;(ii) only limited to the effects of atomic motion and field mode structure on the two-level atom.In this paper,a significative generalized work will be done from the two aspects.In this paper,at first,we bring to bear the full quantum theory,(i) to educe the wave function of the system considering the interaction of a ∧-type three-level moving atom with field under on-resonance condition And the wave function in degenerate raman process JCM considering atomic motion and field mode structure by using the far-off- resonance condition;(ii) to educe the wave function of the system considering the interaction of a V -type three-level atom with field with a time-dependent atom-field coupling under on-resonance condition and the wave function in degenerate raman process JCM with a time-dependent atom-field coupling. Second,we utilize entropy theory,in virtue of the wave function,the effects of the different initial field, the atomic motion and field-mode structure and the time-dependent atom-field couplingcoefficient on the field entropy is discussed at length.The results show that: (1) the atomic motion leads to the periodic evolution of the field entropy,this periodicity does not depend on the statistical distribution and the intensity of the initial field mode,but depends on the atomic velocity v,the length of the cavity L and the field-mode structure parameters p .(2) both on-resonance condition and far-off-resonance condition,when making a suitable choice for parameter sp (this choice is experimentally possible),we can get pure field state for a long time.(3) there are no Schrodinger-cat states in the evolution processes of interaction of the field with the A-type three-level atom.(4) the difference of initial field will produce great effect in field entropy.(5) the perfect periodicity of field entropy has been destroyed due the linear modulation, When the atom-field coupling coefficient changes slowly,the speed of atom entering the statistical state;When the atom-field coupling coefficient changes rapidly,the oscillating frequency of the evolution of entropy is fastened.