Studies On Entanglement Properties In Cavity QED With Decay

Combined quantum mechanics and information science, quantum information is a new subject, which is to study quantum dense coding, quantum communication, quantum computation etc. Because of introduction of quantum entanglement, quantum non-cloned property and quantum superposition and coherence, quantum information exhibits absolute advantages corresponding to its classical counterpart in terms of factoring large number and quantum secure communication. At present, quantum information is attracting more and more attention due to its special charm. Cavity QED is unanimously considered as the best candidate for quantum information process. Its core is to make use of interaction between atoms and cavity modes, to make states evolve, and to prepare and manipulate quantum states. For instance, we can prepare quantum logical gates, generate entangled state and teleportate quantum state etc.Firstly, we present the development of quantum information, and then introduce the theoretical knowledge about cavity QED, demonstrate how to prepare two-atom entangled state and proceed quantum information in cavity QED. In chapter 2, we review the entangled state completely, and introduce several methods to measure entanglement. Chapter 3 is our main work. We present in detailed the case of interaction between ladder-type and lambda-type three levels atoms with bimodal cavity. Furthermore, we discuss the effect of cavity decay on the entanglement and dynamic properties of cavity QED. With numerical computation we obtain the result that atomic population probability, residual entanglement, concurrence between two atoms, average population inversion, average photon number, the fidelities of generating EPR and logical gate decrease with the increase of cavity decay rate when the other relevant parameters are fixed.Our work is helpful for people to deeply understand the interaction between three-level atoms and bimodal cavity. Meanwhile, these works have certain guidance for further study the quantum information process in cavity QED.