Research On The Influence Of Post-selection Von Neumann Measurement On The Properties Of Quantum States

The preparation and optimization of nonclassical quantum states are of great significance in quantum control and quantum information science.For better application,it is necessary to study the properties of radiation field to find quantum states that can better meet the application in information processing.The preparation and optimization of quantum states has always been a hot research topic,and the enhancement of the non-classical properties of quantum states depends on the optimization of quantum states,which in turn depends on quantum measurement technology.In 1988,the weak measurement theory proposed by Y.Aharonov et al.,as a generalized quantum measurement theory,can give a reasonable explanation to the previous debates about some phenomena and theories.In this new measurement theory,system information is obtained through pre-selection and post-selection of the measured system.In order to better distinguish this new measurement theory from the existing weak measurement theory,we generally call this new weak measurement theory post-selection quantum weak measurement.The theory of post-selective quantum weak measurement has been verified by experiments,and has been widely used in various fields of physics to solve many important problems.Recent research results show that this new measurement technique has advantages in quantum state optimization,but there are still many problems to be explored.Since the theory of postselective quantum weak measurement can amplify the weak signals of the system,some essential properties of some classical or semi-classical states will be changed or even new non-classical states will be generated after the measurement.In order to understand the related phenomena in this aspect,we carry out post-selective quantum weak measurement based on the addition of single-photon coherent states.In this paper,we study the high-order compression effect and the properties of Wigner function through post-selective von Neumann measurement of the addition of single-photon coherent states.In the first chapter of this thesis,quantum states and the basic ideas of quantum measurement theory are introduced.In chapter 2,I briefly review the basic concepts of operators and quantum states,then introduce the introduction of quantum states commonly used in quantum optics and quantum information,and then discuss quantum states and their applications in quantum information processing.In chapter 3,the basic idea and application of quantum weak measurement and standard von Neumann measurement theory are introduced,and decoherence is introduced.In chapter 4,the post-selection von Neumann measurement problem based on adding single photon coherent states as pointer states is introduced.Firstly,the basic properties and preparation methods of adding single photon coherent states are introduced,and then the weak measurement model is introduced.Finally,the influence of the postselected von Neumann measurement on the higher order effect of increasing the coherent states of single photons and the phase space distribution is discussed in detail.The fifth chapter is about the theoretical introduction of the module value,and the influence of the module value on the statistics of the photon number based on the increase of the coherent state of the single photon.In the last chapter,the whole paper is summarized and the direction of further research is prospected.