Periodic driving induced helical Floquet channels with ultracold atoms in momentum space

TL;DR

This paper demonstrates the creation of robust helical Floquet channels in ultracold atoms using periodic driving, revealing topological properties and offering a platform for advanced quantum simulation and topological physics studies.

Contribution

It introduces a method to realize and analyze topologically protected Floquet channels in momentum space with ultracold atoms under periodic driving.

Findings

Observation of robust helical Floquet channels

Confirmation of topological origin via Floquet winding numbers

Potential for studying complex Floquet engineering and topological physics

Abstract

Employing the external degrees of freedom of atoms as synthetic dimensions renders easy and new accesses to quantum engineering and quantum simulation. As a recent development, ultracold atoms suffering from two-photon Bragg transitions can be diffracted into a series of discrete momentum states to form a momentum lattice. Here we provide a detailed analysis on such a system, and, as a concrete example, report the observation of robust helical Floquet channels, by introducing periodic driving sequences. The robustness of these channels against perturbations is confirmed, as a test for their topological origin captured by Floquet winding numbers. The periodic switching demonstrated here serves as a testbed for more complicated Floquet engieering schemes, and offers exciting opportunities to study novel topological physics in a many-body setting with tunable interactions.