Study Of Quantum Correlations For Bipartite Systems In Quantum Noisy Environment By Weak Measurement

The investigation of quantum entanglement is a hot topic in quantum optics and quantum information.Quantum entanglement,a kind of nonclassical correlation in quantum world, is a fundamental concept of quantum mechanics. It is well accepted that entanglement plays a crucial role, and it is the invaluable resource in quantum computation and quantum information.Recently, it is realized that entanglement is not the only aspect of quantum correlations, there is a form of quantum discord for quantum correlations. Quantum discord is more robustness than quantum entanglement. In this paper,the signal state of our explore is a special kind of quantum states(X-type quantum state). In this paper, the dynamics properties of geometric quantum discord of the quantum state(X-type quantum state) are studied through the quantum noise environments such as amplitude damping channel 、 phase damping channel and depolarization channel, we obtain the effect quantum resources with the help of weak measurements and quantum measurement reversals in the quantum noise environments. This thesis is organized as follows:In chapter 1, the related knowledge of quantum informationand the research background of quantum correlation are introduced. Then the basic theory of quantum correlation and the measurement method of quantum correlation in two bit system are presented. Finally, the basic theory of weak measurement and control strategy are presented.In chapter 2, the master equation of open quantum systems are briefly described; The quantum noise of amplitude damping channel 、 phase damping damping channel and depolarization channel are presented, and the evolution of density matrix after the initial state respectively through the three kinds of single and double quantum bit channel are presented.In chapter 3, the geometric quantum discord of single and double quantum bit channel respectively through amplitude damping channel 、 phase damping channel and depolarization channel in quantum noise environment after through weak measurements 、 quantum measurement reversals are briefly described. To a certain extent research has shown that weak measurement can protect the geometric quantum discord, and the protection of weak measurement for the geometric quantum discord of only a single quantum bit through channel is better than of double quantum bits quantum.In chapter 4, the summary and the outlook of the thesis are presented.