Direct observation of chiral currents and magnetic reflection in atomic flux lattices

TL;DR

This paper demonstrates the direct engineering and imaging of tunable artificial gauge fields in cold atomic systems, revealing chiral currents and magnetic reflection phenomena, advancing the study of topological matter.

Contribution

It introduces a method to create and control artificial gauge fields in atomic momentum states, including inhomogeneous fields, with site-resolved imaging of resulting atomic dynamics.

Findings

Creation of homogeneous artificial gauge fields of arbitrary value

Direct imaging of chiral currents in atomic lattices

Observation of magnetic reflection of atoms at inhomogeneous gauge field boundaries

Abstract

The prospect of studying topological matter with the precision and control of atomic physics has driven the development of many techniques for engineering artificial magnetic fields and spin-orbit interactions. Recently, the idea of introducing nontrivial topology through the use of internal (or external) atomic states as effective "synthetic dimensions" has garnered attraction for its versatility and possible immunity from heating. Here, we directly engineer tunable artificial gauge fields through the local control of tunneling phases in an effectively two-dimensional manifold of discrete atomic momentum states. We demonstrate the ability to create homogeneous gauge fields of arbitrary value, directly imaging the site-resolved dynamics of induced chiral currents. We furthermore engineer the first inhomogeneous artificial gauge fields for cold atoms, observing the magnetic reflection of atoms incident upon a step-like variation of an artificial vector potential. These results open up new possibilities for the study of topological phases and localization phenomena in atomic gases.