The relation between the entanglement of two atoms and the entanglement of two-mode fields
原子间纠缠和光场模间纠缠的对应关系

By means of negativity and concurrence, we investigate the time evolution of the entanglement of the two atoms and the entanglement between the two modes in the system of two atoms interacting with two-mode fields. We find the two entanglements can swap with each other, and they have a very good coincidence relation under certain conditions. In two -qubit system, negativity and concurrence in the same range can keep identical with each other on the standard of the existence of entanglement, but they may not always keep pace with each other for mixed states of the system.