Quantum Odyssey of Photons
Tobias Schaetz, Ch. Schneider, Martin Enderlein, Thomas M. Huber, R. Matjeschk · ChemPhysChem · 2010
Caution: Pedestrians might cross themselves! Quantum walks, the quantum extension of classical random walks, had already been realized for different quantum particles. Now two walkers realized as photons were observed to pass through the same optical path-network (see picture). For the first time, the two indistinguishable walkers were shown to interfere with each other.