Eriksson, G.Bengtsson, J.Karabulut, E. O.Kavoulakis, G. M.Reimann, S. M.2020-03-262020-03-2620180953-40751361-6455https://dx.doi.org/10.1088/1361-6455/aaa05chttps://hdl.handle.net/20.500.12395/36640We study the temporal evolution of a small number N of ultra-cold bosonic atoms confined in a ring potential. Assuming that initially the system is in a solitary-wave solution of the corresponding mean-field problem, we identify significant differences in the time evolution of the density distribution of the atoms when it instead is evaluated with the many-body Schrodinger equation. Three characteristic timescales are derived: the first is the period of rotation of the wave around the ring, the second is associated with a 'decay' of the density variation, and the third is associated with periodic 'collapses' and 'revivals' of the density variations, with a factor of root N separating each of them. The last two timescales tend to infinity in the appropriate limit of large N, in agreement with the mean-field approximation. These findings are based on the assumption of the initial state being a mean-field state. We confirm this behavior by comparison to the exact solutions for a few-body system stirred by an external potential. We find that the exact solutions of the driven system exhibit similar dynamical features.en10.1088/1361-6455/aaa05cinfo:eu-repo/semantics/closedAccessfew-body systemsexact diagonalizationquantum ringstime evolutionArticle513Q2WOS:000422876400001Q2