The Detection And Research Of Quantum Entanglement And Quantum Correlation

As a vital role in quantum information and quantum computing,quantum entanglement is not only an important object with studied,but also has been widely used in the field of information.The most difficult assignments in the classical information theory can be solved by entanglement properties of quantum states.Since the advent of quantum phenomena,the research on quantum entanglement phenomenon has been made some significant breakthrough.The only drawback is the essence of quantum entanglement still can not be explained perfectly.From the most basic to start,how to judge a quantum state is entanglement? Or other,what is the degree of entanglement of the quantum state? How to measure the degree? Besides,the computing of quantum correlation and entanglement detection in multipartite systems,and quantum correlation of depiction and measurement,etc.A large number of problems wait to be solved.Based on the study of quantum entanglement,non-classical correlation in separable state have been found,which strong evidence the quantum entanglement is only part of the quantum correlation Through studying the reasons of quantum computer beyond the classic computer,a variety of problems about the measurement of correlation were raised.Quantum correlation was come up with the further research of quantum entanglement,and then got great attention.In the process some of the quantum information,quantum correlations also played an irreplaceable role.In the second part of the paper,we make a presentation of the concept of quantum entanglement firstly.Then based on several existing entanglement criterion,we describe the regular form of quantum states by Bloch representation.Because of LF operator doesn't change entanglement of quantum states,by studying form of quantum states we can greatly improve the detection of entanglement efficiency,while strengthening the performance of the existing criterion for detecting entanglement.In the third part of the paper,we firstly introduce some concepts of quantum correlations,and then introduce several common measurement of quantum correlations.Finally we emphatically introduce the definition and calculation of the quantum discord,which enhance the understanding of other measurement.In the fourth part of the paper,we extend the associated computation of quantum discord in 2-qutrit system.Ultimately we get a lower bound of quantum discord.We also enumerate some exceptions to enhancing understanding of quantum discord.