Entanglement properties of two-photon process in three coupling cavities

Three identical cavities are considered each of which contains one two-level atom with the two cavities coupled via a two-photon hopping interaction. Negativity is used to quantify the degree of entanglement. By means of the numerical calculations, the evolution of the entanglement between atoms or between cavities has been investigated. The influence of cavity-cavity coupling coefficient on the entanglement is discussed. The results show that the entanglement between atoms is strengthened, and that between cavities is weakened with cavity-cavity coupling coefficient increasing.