Physicists irreversibly split photons by freezing them in Bose-Einstein condensate

Light can be directed in different directions, usually also back the same way. Physicists from the University of Bonn and the University of Cologne have however succeeded in creating a new one-way street for light. They cool photons down to a Bose-Einstein condensate, which causes the light to collect in optical "valleys" from which it can no longer return. The findings from basic research could also be of interest for the quantum communication of the future.