Combinatorics

Physics

Topology (electrical circuits)

Gapless playback

Weyl semimetal

Mathematics

Electronic band structure

Statistics

Ultracold atom

Coupling (piping)

Semimetal

Band gap

Acoustics

Metallurgy

Materials science

Condensed matter physics

Lattice (music)

Theoretical physics

Spin (aerodynamics)

Fermion

Quantum mechanics

Realization (probability)

Quantum

Thermodynamics

Science

Weyl semimetals are three-dimensional (3D) gapless topological phases with Weyl cones in the bulk band. According to lattice theory, Weyl cones must come in pairs, with the minimum number of cones being two. A semimetal with only two Weyl cones is an ideal Weyl semimetal (IWSM). Here we report the experimental realization of an IWSM band by engineering 3D spin-orbit coupling for ultracold atoms. The topological Weyl points are clearly measured via the virtual slicing imaging technique in equilibrium and are further resolved in the quench dynamics. The realization of an IWSM band opens an avenue to investigate various exotic phenomena that are difficult to access in solids.

Realization of an ideal Weyl semimetal band in a quantum gas with 3D spin-orbit coupling