Experimental Realization Of Entanglement Detection And Adiabatic Quantum Algorithm In Linear Optical Quantum System

Quantum information is an emerging discipline arising from the intersection of quantum physics and classical information science.Applied to the fields of computing,communication,and metrology,it has spawned frontier academic research fields,including quantum computing,quantum communication and quantum precision measurement,and all of which,compared to their classical counterparts,demonstrate potential advantages and broad prospects.In this thesis,focusing on linear optical quantum systems,by developing a high-brightness,high-indistinguishability spontaneous parametric down-conversion based entanglement source,and a high-fidelity two-qubit quantum entanglement gate,we carry out experimental work in three aspects:the preparation of many-body quantum graph states and their entanglement detection,experimental demonstration of non-Abelian adiabatic quantum algorithms based on highperformance shallow linear optical quantum circuits,and the realization of fundamental quantum information tasks in a photonic quantum network.The main results and innovations are as follows:First,we innovatively propose to use generative adversarial model within unsupervised machine learning for the first time to detect bipartite entanglement in unknown quantum graphs state,without prior information.In the experiment,we prepare the unknown quantum pure states and mixed states,and detect bipartite entanglement in them with high precision.Further,we use theoretically optimal entanglement witness operator to experimentally detect the entanglement structure of multipartite quantum graph states for the first time.Then,we perform an experimental demonstration of non-Abelian adiabatic quantum algorithms based on a high-performance shallow linear optical quantum circuit.By embedding a single-qubit gate in a displaced Sagnac interferometer,we develop a deterministic polarization-path hyperentangled two-qubit gate array for the first time,and build a state-of-the-art shallow linear optical quantum circuit.With the help of this high-performance shallow circuit,we solve an independent set problem by realizing the non-Abelian adiabatic quantum algorithm for the first time.Finally,we realize several quantum information fundamental tasks in quantum networks.Based on the high-brightness and high-indistinguishability parametric downconversion based entanglement source developed in the experiment,we successfully fabricated a multi-node,high-fidelity optical quantum network.Firstly,we strictly quantify the number of classical nodes in the network in our experiments for the first time.Next,we demonstrate that pre-shared entanglement quantum network coding can break through the bottleneck problem in classical network transmission.Last,we experimentally realize the entanglement distillation process in quantum networks with the highest probability so far.