We reveal the connection of the recent numerical observations of Krstulovic and Brachet [arXiv:1007.4441] with the general theory of relaxation kinetics of the strongly non-equilibrium Bose-Einstein condensates.
A new mechanism of thermalization involving a direct energy cascade is obtained in the truncated Gross-Pitaevskii dynamics. A long transient with partial thermalization at small scales is observed before the system reaches equilibrium. Vortices are found to disappear as a prelude to final thermalization. A bottleneck that produces spontaneous effective self-truncation and delays thermalization is characterized when large dispersive effects are present at the truncation wave number. Order of magnitude estimates indicate that self-truncation takes place in turbulent Bose-Einstein condensates. This effect should also be present in classical hydrodynamics and models of turbulence.
Starting with a Bose-Einstein Condensate of Rb atoms in equilibrium, the System is brought to turbulence and left to relax under the occurrence of reactions from the introduced excitations. The typical phenomena of the evolution to establishment of the turbulence states are observed. After excitation is removed, the system begins to relax, giving way to diverse phenomena such as the presence of non-thermal fixed points, pre-thermalization and finally equilibrium with or without the reconstitution of the condensate depending of the quantity of injected energy. The work paves the way for the study of the thermalization of an out-of-equilibrium many-body quantum system.