  We show that hybrid structures of topological insulators and materials
without topological protection can be employed to create perfectly conducting
channels hosted in the non-topological part. These states inherit the
topological protection from the proximity of the topological insulator but are
more fragile to time-reversal symmetry breaking because of their extended
character. We explore their formation in the band structure of model hybrid
systems as well as realistic heterostructures involving HgTe/CdTe-based
two-dimensional topological insulators. Using numerical quantum transport
calculations for the HgTe/CdTe material system we propose two experimental
settings which allow for the detection of the induced perfectly conducting
channels, both in the localized and diffusive regime, by means of magneto
conductance and shot noise.
