Kuhnert, M.Geiger, R.Langen, T.Gring, M.Rauer, B.Kitagawa, TakuyaDemler, EugeneAdu Smith, D.Schmiedmayer, J.2014-11-242013Kuhnert, M., R. Geiger, T. Langen, M. Gring, B. Rauer, T. Kitagawa, E. Demler, D. Adu Smith, and J. Schmiedmayer. 2013. Multimode Dynamics and Emergence of a Characteristic Length Scale in a One-Dimensional Quantum System. Physical Review Letters 110, no. 9: 090405.0031-90071079-7114http://nrs.harvard.edu/urn-3:HUL.InstRepos:13421146We study the nonequilibrium dynamics of a coherently split one-dimensional 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.en-USJournal Article2014-11-2410.1103/PhysRevLett.110.090405