Observation of photonic anomalous Floquet Topological Insulators

TL;DR

This paper experimentally demonstrates a photonic anomalous Floquet topological insulator, characterized by a zero Chern number but non-trivial winding number, showcasing robust edge states and phase transitions in a novel topological phase.

Contribution

It provides the first experimental realization of an anomalous topological insulator with zero Chern number, emphasizing the role of winding number in topological characterization.

Findings

Robust chiral edge states observed in the system

Phase transition between topological and trivial phases analyzed

Winding number effectively describes the topological properties

Abstract

Commonly, a two-dimensional topological insulator is characterized by non-zero Chern numbers associated with its band structure. In our work, we present the experimental demonstration of an anomalous topological insulator, for which the Chern numbers are always zero, and the winding number is the appropriate quantity describing the topological character of the system. We probe the robustness of the chiral edge states in such anomalous topological insulators and analyze the phase transition between topological and trivial phase.