Quantum Properties In The Interaction Between Cavity Field And A Multilevel Atom

Content:In this paper, the system of a N-type four-level atom interacting with two-mode SU(1,1) coherent.states is studied by means of the quantum theory, and the state function for the system is derived. Using the state function, the initial light field intensity, the coupling coefficient of the atom - field and the Kerr effect on the field entropy evolution and nonclassical properties in the system is investigated. The field entropy is studied by computer numerical value counting. It has been shown that the evolution of the field entropy is distinctly characteristic of vibration. With the increase of the initial field parameters q and ,the mean values of the evolution curves of the field entropy increase constantly, the oscillation frequency of the evolution curves of the field entropy becomes rapid, and the periodicity of the evolution curves of the field entropy get more obvious when increase, but the range from maximal value to minimal value of field entropy decreases rapidly.This shows that big and q lead to the intense relation of the field-atom. When the coupling coefficient is little, the oscillating frequencies of field entropy are small, the larger the coupling coefficient increases, the bigger of oscillating frequencies of field entropy, when e is much large, the amplitudes of oscillating very little, the mean value of the field entropy is nearly equal to the initial value of the field entropy, that show the field is always in well-distributed statistics mixture, Which shows that the field entropy is sensitive to the coupling coefficient of the atom and the field.At the same time, With the increase of the Kerr medium intensity parameter u, the mean values of the evolution curves of the field entropy don't change much, but the maximal value of them decreases constantly, the range of field entropy also decreases obviously. This shows that the non-linearity action of Kerr medium can weaken the interaction of the field-atom.The quantum properties of field are studied by computer numerical value counting. It has been shown that the two modes of field are always correlated, the influences of the Kerr effect on the correlation intensity between thetwo-mode and on the oscillation of the correlation intensity are obviously related to the initial intensity of the light field. Cauchy-Schwartz inequality is always disobeyed, so the correlation of the two mode of light field is non-classical And When the initial field is weak, The cavity 1 has almost antibunching effect, and with the strong of Kerr effect the more obviously strong of antibunching effect, but photon bunching alternates with photon antibunching in the cavity 2 and Kerr effect is not so obvious. When the initial field is strong, the influence of Kerr effect don't change on the cavity 1,but make bunching effect and antibunching effect weak on the cavity 2.In this paper, the density operator is also induced via V-type atom interacting with a cavity-field through Raman process system in amplitude damping cavity, and the properties of linear entropies for atom-field system for atom and for field in the system is investigated. The results show that the linear entropy of the system and atom are larger than zero except the initial time in a dissipative cavity. The values of which remain a certain degree after some time and increase with the increase of mean photon number. At td, the atom is completely decipherment to the cavity. The field comes back to the initial pure state. But the atom is still in a mixed state. The larger the dissipation, the more rapid the linear entropies of the atom and system tend to the certain degree of mixture. And the larger the mean photon number, the more obvious the dissipation influence on the linear entropy.