Bimorphic Floquet Topological Insulators

TL;DR

This paper introduces bimorphic Floquet topological insulators using periodically modulated on-site potentials, revealing new topological phases and robust edge states in photonic waveguide lattices, expanding the understanding of topological wave transport.

Contribution

It presents a novel class of Floquet topological insulators based on connective chains with modulated potentials, broadening the scope of topological phases beyond traditional methods.

Findings

Identification of multiple non-trivial topological phases including Chern and anomalous chiral states.

Experimental demonstration of strongly confined, topologically protected helical edge states.

Edge states can be moved or halted without losing topological protection.

Abstract

Topological theories have established a new set of rules that govern the transport properties in a wide variety of wave-mechanical settings. In a marked departure from the established approaches that induce Floquet topological phases by specifically tailored discrete coupling protocols or helical lattice motions, we introduce a new class of bimorphic Floquet topological insulators that leverage connective chains with periodically modulated on-site potentials to unlock new topological features in the system. In exploring a 'chain-driven' generalization of the archetypical Floquet honeycomb lattice, we identify a rich phase structure that can host multiple non-trivial topological phases associated simultaneously with both Chern-type and anomalous chiral states. Experiments carried out in photonic waveguide lattices reveal a unique and strongly confined helical edge state that, owing to its origin in bulk flat bands, can be set into motion in a topologically protected fashion, or halted at will, without compromising its adherence to individual lattice sites.