  We investigate a system consisting of one or two topological-insulator leads
which are tunnel coupled to a single dot level. The leads are described by the
one-dimensional Su-Schrieffer-Heeger model. We show that (topological) edge
states cause characteristic features in the dot spectral function, the dot
occupation, and the finite-bias current across the dot. As the kinetic energy
is quenched in the dot region, local two-particle interactions are of
particular relevance there. This motivates us to test whether the
aforementioned edge-state features are robust against such interactions; we
report here that they are either robust or even enhanced. We conclude that the
characteristic features can be used to determine if the leads are in their
topologically non-trivial or trivial phase.
