Extended Data Fig. 2. Floquet band structures at two special points of the topological phase diagram.

a, b, Bulk band structures at the green (a) and centre (b) points of the phase diagram of Fig. 2c in the main text. The green point corresponds to a phase-rotation symmetric network of perfect matched circulators, thus in AFI phase. The red centre point represents a network of reciprocal resonant scatterers, with all bandgaps closed. c, d, Ribbon band structures corresponding to panel a and b, respectively. The perfect circulator network features flat bulk band with dispersionless edge modes regardless of the value of the quasi-energy φ, which can only occur in the AFI phase.