Observation of anomalous {\pi} modes in photonic Floquet engineering

TL;DR

This paper reports the first experimental observation of Floquet topological cc modes in a photonic system, demonstrating boundary modes and high-frequency behaviors in a periodically driven 1D topological model.

Contribution

The study experimentally realizes and verifies Floquet topological cc modes in a photonic waveguide array, providing a versatile platform for exploring time-dependent quantum phases.

Findings

Observation of Floquet cc modes at array boundaries

Demonstration of different behaviors between static and driven topological modes

Universal high-frequency behavior in periodically driven systems

Abstract

Recent progresses on Floquet topological phases have shed new light on time-dependant quantum systems, among which one-dimensional (1D) Floquet systems have been under extensive theoretical research. However, an unambiguous experimental observation of these 1D Floquet topological phases has still been lacking. Here, by periodically bending ultrathin metallic arrays of coupled corrugated waveguides, a photonic Floquet simulator was well designed and successfully fabricated to simulate the periodically driven Su-Schrieffer-Heeger model. Intriguingly, under moderate driven frequencies, we first experimentally observed and theoretically verified the Floquet topological $\pi$ mode propagating along the array's boundary. The different evolutionary behaviors between static and non-static topological end modes have also been clearly demonstrated. Our experiment also reveals the universal high-frequency behavior in perically driven systems. We emphasize that, our system can serve as a powerful and versatile testing ground for various phenomena related to time-dependant 1D quantum phases, such as Thouless charge pumping and manybody localization.