Gap-protected transfer of topological defect states in photonic lattices

Topologically protected states are important in realizing robust excitation transfer between distant sites in photonic lattices. Here, we propose an efficient gap-protected transfer of photons in a scalable one-dimensional waveguide array by transporting the topological defect state of a Su–Schrieffer–Heeger model. The separation between neighboring waveguides is designed according to the Jaynes–Cummings model. As a result, the zero-energy eigenstate is topologically protected from the extended states by a constant energy gap, which leads to a fast and robust excitation transfer. We also show that the transport can be further sped up by the quasi-periodic oscillation induced by the non-adiabatic effect. This scheme has potential applications in scalable quantum information processing.