Research On Preparation And Application Of Multipartite Entangled States

Quantum entanglement is one of the most peculiar properties in quantum mechanics and it is very important in the application of quantum technology such as quantum information and quantum computation.This paper mainly discusses the preparation and application of multipartite entangled states.Firstly,this paper gives a chance to introduce the background and significance of quantum entanglement and the important progress in the study of multi-photon entanglement at home and abroad.Then,this paper also refers to some basic theoretical knowledge of entanglement source and basic knowledge of optical experimental platform.As for the preparation of multi-photon entangled states,this paper mainly introduces the preparation schemes of two-photon entangled states and three-photon entangled states.It can be used to the spontaneous parametric down conversion technique to prepare two-photon entanglement source and three-photon entanglement source,and it can produce the two-photon maximum entanglement state with a fidelity of 99.50% and the three-photon maximum entanglement state with a fidelity of 87.25%.In terms of the application of multi-photon entanglement,this paper mainly introduces the following three main works.First,using two two-photon entangled sources to study the influence of the filter on the HOM interference curve of the independent source.By comparing the theoretical simulation curve with the interference curve measured in the experiment,the experimental and theoretical results were basically consistent.Second,using a three-photon entangled source to prepare a three-photon GHZ state and a group of GHZ-like states,and verify the incompatibility between quantum mechanics and local realism by measuring the violation value of Mermin inequality.Last,on the basis of high-fidelity two-photon entanglement source,it can be prepared to a device that independent quantum random number generator based on positive definite operator measurement.By measuring two-photon entangled states,the quantum random number generator can at most extract up to two bits of random numbers per round,thus improving the generation efficiency of quantum random numbers.