Testing Quantum Nonlocality Based On Mixed State

Quantum nonlocality is one of the most important characteristics in quantum mechanics theory,which is one of the most significant difference between quantum theory and classical theory.It plays an important role in quantum information theory.Up to now,the research on quantum nonlocality test is very extensive,and it has been verified theoretically and experimentally(including the verification methods with and without inequality),which proves the correctness of quantum theory.However,for the quantum nonlocality test,most of them take pure state as the research object.While for the mixed state,the research is less.Because the quantum state usually prepared in actual experiments is a mixed state,and it has an important role in the field of quantum information,it has good practical significance for the quantum nonlocality test for quantum mixed states.The main content of this paper is to the analysis and research the quantum nonlocality test of mixed states based on two different tests without inequality.First of all,a brief review of the quantum nonlocality test and the development process of quantum theory,as well as the corresponding research background,basic concepts,theoretical elaboration and so on,which lays a certain foundation for the following theoretical research.Secondly,we introduce the test logic of Hardy theorem and Hardy-type paradox in detail,and analyze the principle of these two methods to test quantum nonlocality without inequality.The maximum probability of success test that can obtain quantum nonlocality test is 9%and 39%,respectively.The correctness and applicability of the proposed logic are verified.In addition,we also analyze the quantum nonlocality test of Hardy ladder.The research results show that with the increasing of the number of ladders,the maximum success probability gradually increases to 50%.Finally,based on Hardy theorem and Hardy-type paradox,this paper focuses on the quantum nonlocality test based on mixed states.The test results of different mixed states are analyzed.The conditions for different mixed states satisfying the quantum nonlocality test are given.The advantages and disadvantages of two different test methods are compared.Based on Hardy-type paradox,we can test the quantum nonlocality with a high probability of success even though the range of the test conditions is relatively small.Based on Hardy-type paradox,it shows stronger quantum nonlocality.