Cavity-Induced Backscattering In A Two-Dimensional Photonic Topological System

Topological protection of transmission has been demonstrated in the edge channel in topological insulators in the face of bent paths and on-site randomness in the structure. Microwave measurements and couple-mode theory of a topological medium possessing time-reversal symmetry with a cavity adjacent to the edge channel show that spin is not conserved in scattering from the defect. The transmission time is negative near resonance with the defect.