Quantifying and Exploiting Entanglement
Irfan Ali Khan · PhDT · 2006
The aim of this work is to explore the characterization of various entangled parameters of the two-photon state that is created in the process of spontaneous parametric down-conversion, as well as to investigate the potential application of these two-photon states to quantum communication and quantum information processing. The parameters fall into two natural divisions, the discrete-variable and continuous-variable regimes. Polarization-correlated photon pairs are used to explore the discrete-variable regime. Using these polarization-correlated photon pairs we investigate phasecovariant quantum cloning, sum-variance entanglement measures, and unambiguous state-discrimination. Phase-covariant quantum cloning is experimentally demonstrated to provide higher cloning fidelity than a universal quantum cloner. The simplicity of the practical implementation of this cloning method makes this cloner a useful addition to the quantum information and communication toolbox. Next, it is experimentally demonstrated that three, concatenating, sum-variance entanglement measures possess higher sensitivities than the popular Bell entanglement measure, while each requires fewer measurements than a Bell measurement