Observation of the Weyl points and topological edge states in a synthetic Weyl elastic crystal

Weyl points (WPs) have been experimentally observed in optics and air-borne acoustic crystals. Although elastic Weyl physics has been theoretically studied, there is no experimental evidence to date. In this paper, WPs in the elastic wave field are investigated and realized in a synthetic three-dimensional (3D) space by one-dimensional (1D) phononic crystals with acoustic black hole structures. The synthetic 3D space constitutes one physical dimension and two geometrical parameters. Results show that the topological edge states and interface states can be directly observed. Furthermore, some WPs are experimentally visualized in an elastic wave system and the measured data are in good agreement with numerical predictions. This opens a new pathway for manipulating 1D elastic waves in an extraordinary way.