  Low dimensional semiconducting structures with strong spin-orbit interaction
(SOI) and induced superconductivity attracted much interest in the search for
topological superconductors. Both the strong SOI and hard superconducting gap
are directly related to the topological protection of the predicted Majorana
bound states. Here we explore the one-dimensional hole gas in germanium silicon
(Ge-Si) core-shell nanowires (NWs) as a new material candidate for creating a
topological superconductor. Fitting multiple Andreev reflection measurements
shows that the NW has two transport channels only, underlining its
one-dimensionality. Furthermore, we find anisotropy of the Lande g-factor,
that, combined with band structure calculations, provides us qualitative
evidence for direct Rashba SOI and a strong orbital effect of the magnetic
field. Finally, a hard superconducting gap is found in the tunneling regime,
and the open regime, where we use the Kondo peak as a new tool to gauge the
quality of the superconducting gap.
