Light propagation in binary kagome ribbons with evolving disorder.

By introducing evolving disorder in the binary kagome ribbons, we study the establishment of diffusive spreading of flat band states characterized by diffractionless propagation in regular periodic ribbons. Our numerical analysis relies on controlling strength and rate of change of disorder during light propagation while tailoring binarism of the kagome ribbons in order to isolate the flat band with the gap from the rest of the ribbon's eigenvalue spectrum and study systematically its influence on diffusion. We show that the flat band plays a dominant role in the establishment of the diffusion for a given strength and rate of change of disorder, whereas the rest of the ribbon's eigenvalue spectrum induces only quantitative differences in the light spreading regimes. Due to the universality of studied phenomena, our findings may be of interest in various disordered physical systems with flat spectral bands, ranging from photonics to ultracold matter systems and plasmonics.