Floquet Topological Phases in a Photonic Simple Lattice upon On-Site Drives

Floquet engineering provides an amazing way to reshape materials from topologically trivial to non-trivial phases by exerting periodic drives. Among its vast investigations spanning various physical systems, the toolkit via driving on-site potentials only is rarely employed. Here, a Floquet protocol that switches a simple lattice into a non-trivial topological phase merely by driving its on-site potentials is proposed. Non-trivial topology arises from unpaired Floquet drives. Topological zero-quasienergy states are found at boundaries between non-trivial and trivial structures, being protected by sublattice symmetry. These states are experimentally demonstrated in a photonic platform. This approach can be extended to unveil more novel topological phenomena as well as to endow non-trivial properties to a host of materials.