Topological nodal chains in optical lattices

TL;DR

This paper proposes an experimental scheme to realize and detect topological nodal chains in optical Raman lattices, enabling exploration of complex topological phases in cold atom systems.

Contribution

It introduces a method to create and observe topological nodal chains in 3D optical Raman lattices with tunable shapes and symmetry protection.

Findings

Nodal chains are protected by mirror symmetry.

Nodal chain shapes can be detected via spin polarization measurements.

The scheme enables exploration of topological semimetal phases in optical lattices.

Abstract

Topological nodal rings as the simplest topological nodal lines recently have been extensively studied in optical lattices. However, the realization of complex nodal line structures like nodal chains in this system remains a crucial challenge. Here we propose an experimental scheme to realize and detect topological nodal chains in optical Raman lattices. Specifically, we construct a three-dimensional optical Raman lattice which supports next nearest-neighbor spin-orbit couplings and hosts topological nodal chains in its energy spectra. Interestingly, the realized nodal chains are protected by mirror symmetry and could be tuned into a large variety of shapes, including the inner and outer nodal chains. We also demonstrate that the shapes of the nodal chains could be detected by measuring spin polarizations. Our study opens up the possibility of exploring topological nodal-chain semimetal phases in optical lattices.