On-Chip Elastic Wave Manipulations Based on Synthetic Dimension.

Manipulating elastic waves in lower-dimensional mechanical metamaterials has attracted much attention since it lays the foundation for the design of various elastic functional devices, especially for on-chip size. However, due to the experimental challenges, it is very difficult to control elastic waves in higher dimensions. In this Letter, we introduce an extra structural parameter to synthesize and investigate the on-chip Weyl physics in silicon-on-insulator system. Interestingly, we engineer an in-plane pseudomagnetic field to realize chiral Landau levels, which provides a bulk channel supporting robust energy transport. We also observe the pseudomagnetic field-induced boundary states near the diagonal corners, which are quite different from conventional higher order topological corner states. With the aid of the synthetic dimension, we can not only realize the multidimensional elastic wave manipulations, but more importantly, devise a novel strategy to explore the higher dimensional physics on an integrated platform.