Realization of a cross-linked chiral ladder with neutral fermions in an optical lattice by orbital-momentum coupling

TL;DR

This paper demonstrates the experimental creation of a chiral ladder system using ultracold fermions in an optical lattice, revealing chiral currents and topological phase transitions driven by orbital-momentum coupling.

Contribution

It introduces a novel method to realize a cross-linked chiral ladder with neutral fermions using orbital-momentum coupling in an optical lattice, including control of effective magnetic flux.

Findings

Observation of chiral currents via asymmetric momentum distributions.

Demonstration of complex cross links affecting quench dynamics.

Discussion of topological phase transitions in the system.

Abstract

We report the experimental realization of a cross-linked chiral ladder with ultracold fermionic atoms in an optical lattice. In the ladder, the legs are formed by the orbital states of the optical lattice and the complex inter-leg links are generated by the orbital-changing Raman transitions that are driven by a moving lattice potential superimposed onto the optical lattice. The effective magnetic flux per ladder plaquette is tuned by the spatial periodicity of the moving lattice, and the chiral currents are observed from the asymmetric momentum distributions of the orbitals. The effect of the complex cross links is demonstrated in quench dynamics by measuring the momentum dependence of the inter-orbital coupling strength. We discuss the topological phase transition of the chiral ladder system for the variations of the complex cross links.