  We investigate the transport properties of a Fermi-Hubbard chain with an
impurity which is formed by a site with a periodically modulated chemical
potential. We determine the momentum resolved transmission through this
impurity in dependence of the modulation frequency and strength for a single
particle and a pair of fermions. We find that the pair transmission has a very
distinct behaviour from the single particle transmission. Different situations
can occur, where only the single particle or the pair with a certain momentum
are transmitted or filtered out.
