  It has recently been proposed that combining chirality with topological band
theory may result in a totally new class of fermions. These particles have
distinct properties: they appear at high symmetry points of the reciprocal
lattice, they are connected by helicoidal surface Fermi arcs spanning the
entire Brillouin zone, and they are expected to exist over a large energy
range. Additionally, they are expected to give rise to totally new effects
forbidden in other topological classes. Understanding how these unconventional
quasiparticles propagate and interact is crucial for exploiting their potential
in innovative chirality-driven device architectures. These aspects necessarily
rely on the detection of handedness-dependent effects in the two enantiomers
and remain largely unexplored so far. Here, we use scanning tunnelling
microscopy to visualize the electronic properties of both enantiomers of the
prototypical chiral topological semimetal PdGa at the atomic scale. We reveal
that the surface-bulk connectivity goes beyond ensuring the existence of
topological Fermi arcs, but also determines how quasiparticles propagate and
scatter at impurities, giving rise to chiral quantum interference patterns of
opposite handedness and opposite spiralling direction for the two different
enantiomers, a direct manifestation of the change of sign of their Chern
number. Additionally, we demonstrate that PdGa remains topologically
non-trivial over a large energy range, experimentally detecting Fermi arcs in
an energy window of more than 1.6 eV symmetrically centerd around the Fermi
level. These results are rationalized in terms of the deep connection between
chirality in real and reciprocal space in this class of materials, and they
allow to identify PdGa as an ideal topological chiral semimetal.
