Multimode dynamics and emergence of a characteristic length-scale in a   one-dimensional quantum system
  We study the non-equilibrium dynamics of a coherently split one-dimensional (1d) Bose gas by measuring the full probability distribution functions of matter-wave interference. Observing the system on different length scales allows us to probe the dynamics of excitations on different energy scales, revealing two distinct length-scale dependent regimes of relaxation. We measure the crossover length-scale separating these two regimes and identify it with the prethermalized phase-correlation length of the system. Our approach enables a direct observation of the multimode dynamics characterizing one-dimensional quantum systems. 
Maximilian Kuhnert, Remi Geiger, Tim Langen, Michael Gring, Bernhard   Rauer, Takuya Kitagawa, Eugene Demler, David Adu Smit...
cond-mat.quant-gas quant-ph