Ultra-bright source of polarization-entangled photons
  Using the process of spontaneous parametric down conversion in a novel two-crystal geometry, one can generate a source of polarization-entangled photon pairs which is orders of magnitude brighter than previous sources. We have measured a high level of entanglement between photons emitted over a relatively large collection angle, and over a 10-nm bandwidth. As a demonstration of the source intensity, we obtained a 242-$\sigma$ violation of Bell's inequalities in less than three minutes. 
Paul G. Kwiat (1), Edo Waks (1 and 2), Andrew G. White (1), Ian   Appelbaum (1 and 3), Philippe H. Eberhard (4) ((1) Physics...