Quantum State Tomography of a Fiber-Based Source of Polarization- Entangled Photon Pairs

摘要

We report an experimental demonstration of a bright high fidelity single-mode-optical-fiber source of polarization-entangled photon pairs. The source takes advantage of single-mode fiber optics, highly nonlinear microstructure fiber, judicious phase-matching, and the inherent stability provided by a Sagnac interferometer. With a modest average pump power (300 rW), we create all four Bell states with a detected two-photon coincidence rate of 7 kHz per bandwidth of 0.9 nm, in a spectral range of more than 20 nm. To characterize the purity of the states produced by this source, we use quantum- state tomography to reconstruct the corresponding density matrices, with fidelities of 95 % or more for each Bell state,.