Floquet higher order topological insulator in a periodically driven bipartite lattice

TL;DR

This paper introduces a new periodically-driven bipartite lattice model that hosts Floquet higher order topological insulator phases, predicts its experimental realization in optical waveguides, and explores phase transitions between different topological states.

Contribution

The paper proposes a realistic optical waveguide array model for FHOTIs and analyzes phase transitions without breaking lattice symmetry.

Findings

Identification of FHOTI phases with corner modes at eigenphases 0 or π

Prediction of experimental realization in optical waveguide arrays

Observation of phase transitions from first- to second-order topological matter

Abstract

Floquet higher order topological insulators (FHOTIs) are a novel topological phase that can occur in periodically driven lattices. An appropriate experimental platform to realize FHOTIs has not yet been identified. We introduce a periodically-driven bipartite (two-band) system that hosts FHOTI phases, and predict that this lattice can be realized in experimentally-realistic optical waveguide arrays, similar to those previously used to study anomalous Floquet insulators. The model exhibits interesting phase transitions from first-order to second-order topological matter by tuning a coupling strength parameter, without breaking lattice symmetry. In the FHOTI phase, the lattice hosts corner modes at eigenphase $0$ or $\pi$, which are robust against disorder in the individual couplings.