Three-dimensional valley-locked waveguide transport enabled by phononic Weyl nodes

The flexible control of wave transport in three-dimensional (3D) space has long been a challenge. Here, we take advantage of the 3D linear dispersion of Weyl nodes and design a sandwiched valley-Hall crystal for robust acoustic waveguide transport. On the grounds of negligible intervalley scattering, such transport is valley locked and the waveguide shape can be altered in an arbitrary way. We experimentally validate such Weyl-node-based 3D topological transport by fabricating and characterizing a phononic crystal, and robust transmission for distinctive waveguide configurations has been observed. Our work introduces different avenues for implementing 3D valley-locked transport and offers a platform for topological device design.