Transport of one-dimensional interacting Fermions through a barrier

We study the transport properties of one-dimensional (1D) interacting Fermions through a barrier by numerically calculating the Kohn charge stiffness constant and the relative Drude weight. We find that the transport properties of the 1D Hubbard model are quite different from those of the 1D spinless Fermion model. For example, the presence of the attractive interaction between electrons in the 1D Hubbard model actually {\em suppresses} the DC conductance, while a small repulsive interaction {\em enhances} the DC conductance. These results show that the spin degree of freedom plays an important role in the transport properties of the 1D interacting Fermion systems.