Preparation Of Entangled States And Entanglement Calculation

It is well known that the entangled state is a necessary resource in the fields of quantum computation and quantum information.So the generation of the entangled state is very important by means of physical model.Besides,when we generate the entangled state in different model,the measure of entanglement varies as time.Hence it is a significant thing that discussing the evolution property of quantum entanglement has to do with some factors.The paper discusses the generation of two-atom entangled state and three-atom entangled state based on cavity QED by the quantum swapping.Using this scheme we can obtain the entanglement swapping with the success probability of 100%and is insensitive to both the cavity decay and thermal field.Then we studied the quantum entanglement property of the Tavis-Cummings model for two identical two-level atoms interacting with a single-mode field by means of two-photon transition.It is shown by numerical calculation and analysis that the two-photon T-C model has much superiority compared with the one-photon T-C model.Besides,the change entanglement measure between two atoms and the filed entropy is associated with initial state,coupling coefficients and photon number.The results of this paper are as follow below:1.At first,we introduce the domestic and international research state of quantum information and the basic concept and theory of the quantum entanglement.2.We generate the two-atom entanglement state and three-atom entanglement state based on cavity QED model using entanglement swapping.3.We discussed the quantum entanglement of the two-photon Tavis-Cummings model.In our paper the innovations have:we realize the generation of two-atom and three-atom entangled state by entanglement swapping based on cavity QED.The scheme has two advantages:1.it is insensitive to both the cavity decay and thermal field.2.it has the success probability of 100%for two atoms system and three atoms system,respectively.Then we discuss the quantum entanglement of the two-photon Tavis-Cummings model by quantum reduced entropy,and concurrence.We obtain that the two-photon T-C model has much superiority compared with the one-photon T-C model.Besides,the change entanglement measure between two atoms and the filed entropy is associated with initial state,coupling coefficients and photon number.