Title: Ultracold bosonic scattering dynamics off a repulsive barrier: coherence loss at the dimensional crossover,
Abstract: We explore the impact of dimensionality on the scattering of a small bosonic
ensemble in an elongated harmonic trap off a centered repulsive barrier,
thereby taking particle correlations into account. The loss of coherence as
well as the oscillation of the center of mass are studied and we analyze the
influence of both particle and spatial correlations. Two different mechanisms
of coherence losses in dependence of the aspect ratio are found. For small
aspect ratios, loss of coherence between the region close to the barrier and
outer regions occurs, due to spatial correlations, and for large aspect ratios,
incoherence between the two density fragments of the left and right side of the
barrier arises, due to particle correlations. Apart form the decay of the
center of mass motion induced by the reflection and transmission, further
effects due to the particle and spatial correlations are explored. For tight
transversal traps, the amplitude of the center of mass oscillation experiences
a weaker damping, which can be traced back to the population of a second
natural orbital, and for a weaker transversal confinement, we detect a strong
decay, due to the possibility of transferring energy to transversal excited
modes. These effects are enhanced if the aspect ratio is integer valued.