Experimental Research On Optical Quantum Information Processing Based On Path-polarization Hyper-entanglement

In this thesis,we introduce the technique of ultra-bright source of entangled photon pair based on spontaneous parametric down-conversion(SPDC)in PPKTP crystal and the preparation of hyper-entangled states based on the path-polarization degree of freedom.Here,the various hyper-entangled states were prepared and their applications in optical quantum information processing experiments.The main results of this paper are listed as follows:1.The quantum walk(QW)model is used to realize the preparation of high-dimensional entangled states.Quantum walking is an important branch of quantum information.The study of changes in quantum properties during quantum random walks is currently one of the most active frontiers.Due to the mutual influence and interference between coins and walkers,the quantum walking model is a good entanglement generator.In this paper,the entanglement in quantum walking con-trolled by a quantum coin related to the number of steps is studied,and it is used in the preparation of an arbitrary-dimensional coin-walker hyper-entangled state.2.The GHZ state,Cluster state,W state,and other multi-qubit entangled states are prepared by the hyper-entanglement between the polarization degrees of freedom and the path degrees of freedom.It shows how to effectively deduce the coherence of quantum states by measuring a small number of observables in experiments based on the theory of spectrum estimation and the stabilizer theory.The quantization of coherence is a fundamental problem in quantum information processing and basic physics.It is helpful to save resources to infer the range of coherence without using tomography,especially for large-scale multi-body systems.3.The hidden teleportation power of the high-dimensional weak entangled states and the activation method of the power are studied in our work.A class of states is used as an example to demonstrate the activation effect of the local filtering operation on the hidden teleportation power of the entangled states.The two parties sharing the entangled state introduce path information of photon as an auxiliary qubit to realize the Bell-State Measurement(BSM),that is through polarization-path hyper-entanglement to carry out the quantum teleportation.Quantum tele-portation plays a crucial role in the field of quantum information,and teleportation power is also an important index of entangled states.