Figure 4: Protected edge states.
(a) Band structure of SrCu2(BO3)2 on a cylindrical strip periodic in x, but with open edges along y. The width along y is taken to be very large. We recover the bulk states corresponding to three triplon bands. In addition, four edge states appear, connecting the Chern bands. Edge modes shown in blue and cyan (red and brown) are left-movers (right-movers). (b) Wavefunctions of the four edge states for an arbitrary kx on a strip of width W=8 dimers. The colour of the dimer bond represents the triplon weight with black corresponding to zero. Right-moving edge states are localized on the bottom edge, whereas left-movers are localized on the top edge.
