Entanglement for a Bimodal Cavity Field Interacting with a Two-Level Atom

Negativity has been adopted to investigate the entanglement in a system composed of a two-level atom anda two-mode cavity field.Effects of Kerr-like medium and the number of photon inside the cavity on the entanglementare studied.Our results show that atomic initial state must be superposed,so that the two cavity field modes can beentangled.Moreover,we also conclude that the number of photon in the two cavity mode should be equal.The interactionbetween modes,namely,the Kerr effect,has a significant negative contribution.Note that the atom frequency and thecavity frequency have an indistinguishable effect,so a corresponding approximation has been made in this article.Theseresults may be useful for quantum information in optics systems.