Macrorealism And Experimental Verification Of Leggett-Garg Inequality

The rapid advancement of quantum information science is inseparable from the physical support of quantum theory.Compared with classical theory,quantum mechanics presents people with more novel,complicated and even visual phenomena that are difficult to understand.The coherent superposition of quantum states is an important feature of quantum mechanics that is different from the classical world.The introduction of Leggett-Garg's inequality provides a powerful criterion for the differentiation and definition of macrorealism theoretical and experimental research.The research work of this paper is mainly based on the experimental verification of Leggett-Garg inequality.The specific content is divided into the following two aspects:Firstly,the experimental verification of no-signaling Leggett-Garg inequality violation under ambiguous measurement is realized based on linear optical system.This experiment mainly aims at the controversial macrorealism problem,the Leggett-Garg inequality is put forward is to test the macroscopic reality.In this part,we realize a quantum optical three-level system experiment with different path and polarization mode,and use single photon to realize the maximum violation of Leggett-Garg inequality without signal in detection time under ambiguous measurement and unambiguous measurement,which reflects the signal transmission generated by the measurement.It is found that,in the case of unambiguous measurement,the violation of Leggett-Garg inequality,although it can be explained by signal in the experiment,still cannot achieve the violation of the modified Leggett-Garg inequality,and the difference is that in the case of ambiguous measurement,While the experimental measurement satisfies no-signaling-in-time,the violation of Leggett-Garg inequality is verified,which is of great significance for verifying the macrorealism of no loophole.Secondly,the experimental discussion of standard Leggett-Garg inequality and two classes of variation based on macrorealism foundation hypothesis is realized under different quantum states.Firstly,the variation of the first class Leggett-Garg inequality of 3-time is compared with the standard Leggett-Garg inequality.It can be found that the quantum violation of the variant is greater than the Leggett-Garg inequality in the standard form.Next,a second class of variant is then proposed.By expanding to n-time,it is found that the quantum violation increases with the increase of n,even under the qubit system.According to the existing experimental technical conditions,we discuss the situation of n=5 at most in the experiment,and the experimental results are in good agreement with the theory.