Quantum State Preparation,Evolution And Measurement Based On Linear Optics

Quantum information aims to study the method of processing information outperform classical methods by using principles of quantum mechanics.The techniques developed for quantum information processing also provide new methods to study quantum mechanics.Photons are able to be easily manipulated by linear-optical elements and robust to environmental noise,thus provide a promising platform for quantum experiments.In this thesis,we consider experiments with photon source generated by spontaneous parametric down-conversion and linear-optical elements.We introduce the quantum state preparation,evolution and measurement based on linear optics in the context of their applications in quantum simulation,quantum computation and research on basic features of quantum mechanics.This thesis contains two main parts,physical realization of quantum information processes and verification of basical features of quantum mechanics.We realize multiple quantum information processes,including quantum simulation and quantum computation.(a)Based on the preparation of two-photon polarization-entangled state,we experimentally simulate the ground state of an Ising spin chain and characterize the structural changes.This simulation of the Ising model with linear quantum optics might open the door to the future studies which connect quantum information and condensed-matter physics.(b)We prepared high dimensional state encoded using polarization and spatial modes of single photon,and then realize quantum centrality algorithm based on continuous-time quantum walk.The experiment sucessfully gives the center of a four-vertex star graph,and provides an effective method for realizing high-dimensional quantum evolution.(c)We realize nonunitary discretetime quantum walk,and based on which we detecte topological invariants of the system.Futhermore,We confirm the topological properties by observing localized edge states and demonstrating the robustness of the topological properties against disorder.Our work would stimulate further studies of topological phenomena in nonunitary quantum dynamics.(d)We realize permutation operations on two-photon polarization states,and then realize quantum permutation algorithm to determine the parity of the performed permutation operation.Our experiment sucessfully solve the problem with almost twice faster than any classical algorithm,and provide a method for manipulation of multi-photon state.We investigate contextuality and its relation with non-locality with quantum systems.(a)We perform cascaded single-qubit rotation followed by a two-outcome measurement to realize positive-operator valued measurement without extend the dimension of the system.We experimentally implement the LSW test using the measurement and violate the LSW inequality,thus ruling out non-contextuality within the minimal system.Besides,our experiment paves the way for further developments,which are dependent on positive-operator valued measurement.(b)We prepare 3-dimensional state encoded using polarization and spatial modes of single photon,and then realize joint measurements of two projectors via transforming the basis of the state.With such setup,we exeprimentally violate the entropic contextual inequality,thus provied the first rigorous demonstration of the entropic test of quantum contextuality and the first detection of information deficit in a single local system.Our method to test the entropic contextuality sheds new light on the conflict between quantum mechanics and noncontextual realistic models,and paves the way for further research on fundamental quantum resources.(c)We prepare a two-party system including a qutrit system and another qubit system to test non-locality,and the qutrit subsystem is used to test contextuality as well.We test both CHSH inequality and KCBS inequality for each state.The experimental results give the first evidence of a tradeoff between locally contextual correlations and spatially separated non-local correlations imposed by quantum theory,and provides evidence that entanglement is a particular manifestation of a more fundamental quantum resource.Our experiment opens the door to experimentally observing other interesting phenomena such as quantum nonlocality based on local contextuality,and sheds new light for further explorations of this quantum resource.