  We present a time-dependent density-matrix renormalization group
investigation of the quantum distillation process within the Fermi--Hubbard
model on a quasi-1D ladder geometry. The term distillation refers to the
dynamical, spatial separation of singlons and doublons in the sudden expansion
of interacting particles in an optical lattice, i.e., the release of a cloud of
atoms from a trapping potential. Remarkably, quantum distillation can lead to a
contraction of the doublon cloud, resulting in an increased density of the
doublons in the core region compared to the initial state. As a main result, we
show that this phenomenon is not limited to chains that were previously
studied. Interestingly, there are additional dynamical processes on the two-leg
ladder such as density oscillations and selftrapping of defects that lead to a
less efficient distillation process. An investigation of the time evolution
starting from product states provides an explanation for this behaviour.
Initial product states are also considered, since in optical lattice
experiments such states are often used as the initial setup. We propose
configurations that lead to a fast and efficient quantum distillation.
