Experimental interference of independent photons
  Interference of photons emerging from independent sources is essential for modern quantum information processing schemes, above all quantum repeaters and linear-optics quantum computers. We report an observation of non-classical interference of two single photons originating from two independent, separated sources, which were actively synchronized with an r.m.s. timing jitter of 260 fs. The resulting (two-photon) interference visibility was 83(+/-)4 %. 
Rainer Kaltenbaek, Bibiane Blauensteiner, Marek Zukowski, Markus   Aspelmeyer, Anton Zeilinger