Zitterbewegung, Bloch Oscillations and Landau-Zener Tunneling in a   Quantum Walk
  We experimentally investigate a discrete time quantum walk in a system of coupled fiber loops and observe typical phenomena known from the wave propagation in periodic structures as ballistic spreading or an oscillation between two internal quantum states similar to Zitterbewegung (trembling motion). If a position-dependent phase gradient is applied we find localization and Bloch oscillations of the field for moderate as well as Landau-Zener tunneling for strong phase gradients. 
Alois Regensburger, Christoph Bersch, Benjamin Hinrichs, Georgy   Onishchukov, Andreas Schreiber, Christine Silberhorn and U...
quant-ph