Tuning anomalous Floquet topological bands with ultracold atoms

TL;DR

This paper demonstrates the experimental creation and control of novel anomalous Floquet topological states in ultracold atoms using Floquet engineering, revealing exotic topological phases and edge modes.

Contribution

It introduces a high-precision method to manipulate Floquet band topology via band inversion surfaces in ultracold atoms, uncovering new anomalous topological states.

Findings

Identification of an anomalous Floquet valley-Hall state with valley-protected edge modes

Observation of a chiral state with high Chern number

Experimental control of Floquet band topology through BIS configurations

Abstract

The Floquet engineering opens the way to create new topological states without counterparts in static systems. Here, we report the experimental realization and characterization of new anomalous topological states with high-precision Floquet engineering for ultracold atoms trapped in a shaking optical Raman lattice. The Floquet band topology is manipulated by tuning the driving-induced band crossings referred to as band inversion surfaces (BISs), whose configurations fully characterize the topology of the underlying states. We uncover various exotic anomalous topological states by measuring the configurations of BISs which correspond to the bulk Floquet topology. In particular, we identify an unprecedented anomalous Floquet valley-Hall state that possesses anomalous helicallike edge modes protected by valleys and a chiral state with high Chern number.