  We investigate the propagation of spin impurity atoms through a strongly
interacting one-dimensional Bose gas. The initially well localized impurities
are accelerated by a constant force, very much analogous to electrons subject
to a bias voltage, and propagate as a one-dimensional impurity spin wave
packet. We follow the motion of the impurities in situ and characterize the
interaction induced dynamics. We observe a very complex non-equilibrium
dynamics, including the emergence of large density fluctuations in the
remaining Bose gas, and multiple scattering events leading to dissipation of
the impurity's motion.
