  SnTe materials are one of the most flexible material platforms for exploring
the interplay of topology and different types of symmetry breaking. We study
symmetry-protected topological states in SnTe nanowires in the presence of
various combinations of Zeeman field, s-wave superconductivity and
inversion-symmetry-breaking field. We uncover the origin of robust corner
states and hinge states in the normal state. In the presence of
superconductivity, we find inversion-symmetry-protected gapless bulk Majorana
modes, which give rise to quantized thermal conductance in ballistic wires. By
introducing an inversion-symmetry-breaking field, the bulk Majorana modes
become gapped and topologically protected localized Majorana zero modes appear
at the ends of the wire.
