Experimental Research On Quantum Correlations Based On High Fidelity Multiphoton Entangled Source

The research on quantum correlations is the core issue for quantum information science, it not only gives us deeper insight into quantum theory, the quantum correla-tions are also essential resource for quantum technology. For example, quantum en-tanglement is the core resource for quantum communication and quantum computation, quantum nonlocality is the necessary resource for device-independent quantum infor-mation tasks, quantum coherence is the core resource for quantum metrology, and so on. Nowadays, the quantum correlations of bipartite system are well understood, well there remains a lot of unexplored area for multipartite system. For the several qubits system’s quantum simulation and the research of quantum correlations, linear optical system is undoubtedly the most convenient and mature experiment platform. The main works of this thesis are listed below:1. We design and realize a new kind of "sandwichlike" entangled photon source. The new source has a higher brightness and collection efficiency. Using such sources we successfully generate a high-fidelity (88.4%) six-photon GHZ state. And for the first time, we experimentally demonstrate the six-photon quantum nonlocality in an all-versus-nothing manner, which pushes multiphoton nonlocality studies forward to the six-photon region. In addition, we also give a method to construct multipartite GHZ argument.2. We propose and experimentally demonstrate a new scheme to prepare the four-photon linear cluster state, which greatly improve the success probability than the original scheme. In addition, our scheme can extend to generate cluster chain of arbitrary length.3. We experimentally test the genuine multipartite nonlocality in the nonsignaling s-cenario, with two classes of tripartite entangled states. When limited in the binary inputs and outputs scenario, these two kinds of states can hardly exhibit Svetlich-ny’s nonlocality. From the viewpoint of resources, the new definition of genuine multipartite nonlocality would have larger range of applications.4. Two works about quantum coherence:We experimentally demonstrate a method to evaluate quantum coherence without tomography, by performing Bell state measurement on two copies of the unknown state, we can get the lower bound of its quantum coherence; We experimentally demonstrate the frozen quantum coherence of a composite system under particular noise channel.