Entanglement dynamics of N two-level atoms interacting with the coherent field in the presence of the nonlinear Kerr Medium

We study the dynamics of global quantum discord and von Neumann entropy for systems composed of two, three, and four two-level atoms interacting with the single-mode coherent field under the influence of a nonlinear Kerr medium. The collapses and revivals of the global quantum discord and von Neumann entropy are observed for different values of the nonlinear Kerr medium parameter for both initial pure and mixed states. Moreover, it is found that at higher values of the nonlinear Kerr medium parameter, the magnitude of the revivals of quantum entanglement is suppressed. It is also noted that for mixed states global quantum discord shows comparatively damped oscillations as compared to the pure states. It is worth mentioning that by increasing the average number of photons in the system, quantum entanglement and quantum discord exhibit damping behavior. Furthermore, the revival time of both the global quantum discord and von Neumann entropy increase with the increase in the nonlinear Kerr medium parameter, for the systems with a relatively large number of atoms.