  We study spinless fermions with repulsive nearest-neighbor interactions
perturbed by an impurity particle or a local potential quench. Using the
numerical time-evolving block decimation method and a simplified analytic
model, we show that the pertubations create a soliton-antisoliton pair. If
solitons are already present in the bath, the two excitations have a
drastically different dynamics: The antisoliton does not annihilate with the
solitons and is therefore confined close to its origin while the soliton
excitation propagates. We discuss the consequences for experiments with
ultracold gases.
