Experimental Research Of Quantum Entanglement And Quantum Nonlinearity

In the quantum communication field,quantum states are explored as the carrier of information.To extract the encoded information from the transmitted quantum states,accurate discrimination of the quantum states that carry the information is required.However,after transmission in the channel,two quantum states that were originally orthogonal will become non-orthogonal and even highly overlapping due to the influence of noise.Therefore,how to discriminate non-orthogonal quantum states is an essential problem in quantum communication.The efficiency and reliability of quantum states discrimination determine the quality of quantum communication.The prerequisite for applying quantum information and implementing quantum communication is to prepare,store,and manipulate quantum information,and the “information” here usually refers to “quantum entanglement”.Quantum entanglement is one of the most basic resources of quantum communication and quantum information.Two works of the related directions are introduced in this paper.Firstly,a new scheme based on quantum nonlinearity which is different from the existing schemes is discussed and experimentally realized with linear optical elements in this paper.In this scheme,quantum nonlinearity is induced by post-selecting the polarization qubit based on a measurement result obtained for the spatial qubit.Secondly,violations of the Clauser-Horne-Shimony-Holt(CHSH)inequality are studied in a special experimental scenario,which is known as asymmetric Bell experiment.In this specific scenario,weakly entangled states generate stronger nonlocal effects than their maximally entangled counterparts.