“The photons were contained in ultrashort laser pulses lasting just just 150 femtoseconds and were entangled by passing them through two so-called nonlinear optical crystals. A thin slab of barium borate first split a single photon into two of photons lower energy with correlated angular momenta. They were then entangled via their polarization, too, by sending them through a crystal of a yttrium-vanadium compound.” Yeah…