Figure 3: Snapshots of one-way propagating topological edge states immune to backscattering at a sharp zigzag defect.

Here the cyclotron frequency , which corresponds to B₀=0.9 T. The driving frequency for the point source is , which corresponds to f=12.7 GHz. (Refer to Methods: Theoretical model). (a) Configuration-I: a 2DEG is in contact with vacuum under a single-domain magnetic field. (b) Configuration-II: a 2DEG is uniformly filled in the whole space under an opposite-domain magnetic field. Note that the profile is plotted for the electric scalar potential, which is non-zero in the vacuum region. The difference between a and b on the wavelengths is consistent with the slightly different dispersion slope of the topological edge states between Configuration-I and II. (See online Supplementary Movies 1 and 2 for real-time evolution).