| Entanglement is one of the most intriguing characteristics of quantum mechanics and plays as the key resources in the quantum information processing and computation. It has both theoretical and experimental significance, also can be used to test basis problems in quantum mechanics. It is significant to study the quantum entanglement quantitatively and it's application in the field of quantum information. In recent years, quantum information science, which mainly includes quantum computer and quantum communication, has evolved as a new research field.In quantum information process, because of the inevitable couple between the quantum system and environment, the quantum system loses its quantum characteristics such as nonlocality and entanglement if it is open to the environment. It is important to study how the quantum property such as entanglement, coherence, and nonlocality evolve with time.In this paper, we research the entanglement of quantum and it's decoherence. The main content of this dissertation is as follows:First, we review the history of quantum states and the main advances in the measure of entanglement. Then, we investigate the time evolution of entanglement in two-photon Tavis-Cummings model .The results show that the evolution of two-atom entanglement appears with periodicity and depends on the two-atom coupling degree and the detuning degree.Second, we investigate the entanglement time evolution and the phenomenon of quantum decoherence in Tavis-Cummings model. The results show that the two-atom entanglement state and decoherence time appear with periodicity and depend on the two-atom initial state, the dipole-dipole coupling intensity between two atoms and the field state. |
