A minimal Weyl semimetal

Quantum Simulation Many compounds have now been identified as Weyl semimetals, materials with an unusual electronic band structure characterized by the so-called Weyl points. Weyl points always appear in pairs, but the solid-state materials studied so far have at least four. Wang et al. engineered a Weyl semimetallic state with the minimum number of Weyl points (two) in a gas of ultracold atoms trapped in an optical lattice (see the Perspective by Goldman and Yefsah). To do that, the researchers had to create three-dimensional spin-orbit coupling in this system. The relative simplicity of the resulting band structure will make it easier to observe the unusual effects associated with this state. Science , this issue p. [271][1]; see also p. [234][2] [1]: /lookup/doi/10.1126/science.abc0105 [2]: /lookup/doi/10.1126/science.abg0892