  Disorder is the primary obstacle in current Majorana nanowire experiments.
Reducing disorder or achieving ballistic transport is thus of paramount
importance. In clean and ballistic nanowire devices, quantized conductance is
expected with plateau quality serving as a benchmark for disorder assessment.
Here, we introduce ballistic PbTe nanowire devices grown using the
selective-area-growth (SAG) technique. Quantized conductance plateaus in units
of $2e^2/h$ are observed at zero magnetic field. This observation represents an
advancement in diminishing disorder within SAG nanowires, as none of the
previously studied SAG nanowires (InSb or InAs) exhibit zero-field ballistic
transport. Notably, the plateau values indicate that the ubiquitous valley
degeneracy in PbTe is lifted in nanowire devices. This degeneracy lifting
addresses an additional concern in the pursuit of Majorana realization.
Moreover, these ballistic PbTe nanowires may enable the search for clean
signatures of the spin-orbit helical gap in future devices.
