Weyl points and topological nodal superfluids in a face-centered cubic optical lattice

TL;DR

This paper demonstrates how a face-centered cubic optical lattice can host Weyl points and topological nodal superfluids in ultracold atoms, with controllable Weyl point configurations and surface states.

Contribution

It introduces a simple scheme to realize Weyl points and topological nodal superfluids in shaken FCC optical lattices with ultracold atoms, highlighting their controllability and topological features.

Findings

Weyl points naturally appear in Floquet band structures of shaken FCC lattices.

Attractive interactions induce topological nodal superfluids with Weyl points in quasiparticle spectra.

The topological charge of Weyl points can be tuned from 2 to 1 by adjusting interactions.

Abstract

We point out that a face-centered cubic (FCC) optical lattice, which can be realised by a simple scheme using three lasers, provides one a highly controllable platform for creating Weyl points and topological nodal superfluids in ultracold atoms. In non-interacting systems, Weyl points automatically arise in the Floquet band structure when shaking such FCC lattices, and sophisticated design of the tunnelling is not required. More interestingly, in the presence of attractive interaction between two hyperfine spin states, which experience the same shaken FCC lattice, a three-dimensional topological nodal superfluid emerges, and Weyl points show up as the gapless points in the quasiparticle spectrum. One could either create a double Weyl point of charge 2, or split it to two Weyl points of charge 1, which can be moved in the momentum space by tuning the interactions. Correspondingly, the Fermi arcs at the surface may be linked with each other or separated as individual ones.