  Commonly, a two-dimensional topological insulator is characterized by
non-zero Chern numbers associated with its band structure. In our work, we
present the experimental demonstration of an anomalous topological insulator,
for which the Chern numbers are always zero, and the winding number is the
appropriate quantity describing the topological character of the system. We
probe the robustness of the chiral edge states in such anomalous topological
insulators and analyze the phase transition between topological and trivial
phase.
