Bose-Einstein Condensate on a Synthetic Topological Hall Cylinder

TL;DR

This paper demonstrates a Bose-Einstein condensate on a synthetic cylindrical surface with a net radial synthetic magnetic flux, revealing topological band structures and transitions in a highly controllable atomic system.

Contribution

It introduces a method to simulate topological quantum matter on a synthetic cylindrical surface using ultracold atoms, uncovering symmetry-protected topological bands and their manipulation.

Findings

Observation of a topological band structure on the Hall cylinder

Identification of symmetry-protected topological band crossings

Control of topological transitions via synthetic magnetic flux

Abstract

The interplay between matter particles and gauge fields in physical spaces with nontrivial geometries can lead to novel topological quantum matter. However, detailed microscopic mechanisms are often obscure, and unconventional spaces are generally challenging to construct in solids. Highly controllable atomic systems can quantum simulate such physics, even those inaccessible in other platforms. Here, we realize a Bose-Einstein condensate (BEC) on a synthetic cylindrical surface subject to a net radial synthetic magnetic flux. We observe a symmetry-protected topological band structure emerging on this Hall cylinder but disappearing in the planar counterpart. BEC's transport observed as Bloch oscillations in the band structure is analogous to traveling on a M\"obius strip in the momentum space, revealing topological band crossings protected by a nonsymmorphic symmetry. We demonstrate that breaking this symmetry induces a topological transition manifested as gap opening at band crossings, and further manipulate the band structure and BEC's transport by controlling the axial synthetic magnetic flux. Our work opens the door for using atomic quantum simulators to explore intriguing topological phenomena intrinsic in unconventional spaces.