Fig. 5. Breakdown threshold of the robustness.

a Theory and b Experimental evolution of space-averaged displacement <r²> = <x² + y²> as a function of step number under different lattice disorders. For disorder strength lower than the threshold η = 1, the disorder increases the effective spatial diameter of the corner skin mode, as shown in the evolution of average displacement with time. For disorders higher than the threshold, light diffusively spreads to large distances on the lattice. Standard deviations are also shown at each step.