Generating polarization-entangled photon pairs using cross-spliced   birefringent fibers
  We demonstrate a novel polarization-entangled photon-pair source based on standard birefringent polarization-maintaining optical fiber. The source consists of two stretches of fiber spliced together with perpendicular polarization axes, and has the potential to be fully fiber-based, with all bulk optics replaced with in-fiber equivalents. By modelling the temporal walk-off in the fibers, we implement compensation necessary for the photon creation processes in the two stretches of fiber to be indistinguishable. Our source subsequently produces a high quality entangled state having (92.2 \pm 0.2) % fidelity with a maximally entangled Bell state. 
Evan Meyer-Scott, Vincent Roy, Jean-Philippe Bourgoin, Brendon L.   Higgins, Lynden K. Shalm and Thomas Jennewein
quant-ph physics.optics