Observation of amplitude-driven nonreciprocity for energy guiding

Imagine a tabletop composed of atoms that are nonlinearly and nonreciprocally coupled towards its center. A light tap on the surface generates typical nondispersive acoustic waves across the plane. In contrast, a hard hit triggers nonlinear nonreciprocity, directing energy towards the center, regardless of the impact location. By employing an extended Hatano-Nelson model and a highly configurable active acoustic metamaterial, the authors demonstrate here nonreciprocal systems where nonlinearities can strategically control energy guiding.