Down-conversion source of positively spectrally correlated and   decorrelated photon pairs at telecom wavelength
  The frequency correlation (or decorrelation) of photon pairs is of great importance in long-range quantum communications and photonic quantum computing. We experimentally characterize a spontaneous parametric down conversion (SPDC) source, based on a Beta-Barium Borate (BBO) crystal cut for type-II phase matching at 1550 nm which emits photons with the positive or no spectral correlations. Our system employs a carefully designed detection method exploiting two InGaAs detectors. 
Thomas Lutz and Piotr Kolenderski and Thomas Jennewein
quant-ph physics.optics