Clauser-Horne-Shimony-Holt Violation Versus Mixedness And Fidelity Of Teleportation

The combination of quantum mechanics and classical information theory yields the new subject of quantum information theory. In quantum information science, quantum state is the carrier of quantum information; the processing of information depends on quantum state and its manipulation in the final analysis. Quantum mechanics is the foundation of quantum information, which primarily study quantum information processing, Including quantum computer,quantum communication and quantum key distibution. when we applied the properties of quantum mechanics to information, classical limit of information theoy could be exceeced in many ways, and we can accomplish many unimaginable tasks for classical information procesing, In the quantum information, quantum teleportation, CHSH inequality, mixedness is important study problem, has always attracted considerable attention.This thesis investigates the relation of CHSH violation, the fidelity of teleportation and mixedness, and then discuss the entropy and the degree of entangment, then a series of significant results have been obtained as follows:The first part intrduced the applications of the quantum teleportation. Part two is a simple review of the history in research about the quantum teleportation,at the same time, summarize its latest progress. Pate three do some specific research with two qubits state. The results indicate that the structure for general two qubit states seems to be the same. We can obtain the same maximal fidelity of teleportation when linear entropy is minimal, but CHSH violation is maximal.To this end, We introduced the tight upper bound and lower bound for the fidelity of teleportation for given values of the concurrence.The last section, discuss the relationship between entopy and the degree of entanglement. The results show that, we can measure the degree of entanglement between the two pure state system with Von Neumann reduced entropy.Between two mixed state can measure the degree of entanglement with quantum relative entropy.