Temporal condensed matter physics in gas-filled photonic crystal fibers
  Raman effect in gases can generate an extremely long-living wave of coherence that can lead to the establishment of an almost perfect periodic variation of the medium refractive index. We show theoretically and numerically that the equations, regulate the pulse propagation in hollow-core photonic crystal fibers filled by Raman-active gas, are exactly identical to a classical problem in quantum condensed matter physics -- but with the role of space and time reversed -- namely an electron in a periodic potential subject to a constant electric field. We are therefore able to infer the existence of Wannier-Stark ladders, Bloch oscillations, and Zener tunneling, phenomena that are normally associated with condensed matter physics only, now realized with purely optical means in the temporal domain. 
Mohammed F. Saleh, Andrea Armaroli, Truong X. Tran, Andrea Marini,   Federico Belli, Amir Abdolvand, Fabio Biancalana
physics.optics nlin.PS