Recent studies classified "intrinsic", "symmetry protected", and other topological properties of matter. The paper (Topological states in photonic systems) claims that "The transport of many topological interfacial states is immune to fabrication imperfections".
This is a really strong statement. When are topological edge/interface states immune to what disorder? I'm reminded of the IQHE experiment, showing that disorder affects the plateaus of hall conductance.And if disorder is large enough, it may change the value of hall conductance.(Reference?)