Nonlinear wave dynamics on a chip

Shallow-water waves are a notable example of nonlinear hydrodynamics, giving rise to phenomena such as tsunamis and undular waves. These dynamics are typically studied in hundreds-of-meters-long wave flumes. In this work, we demonstrate a chip-scale wave flume, which exploits nanometer-thick superfluid helium films and optomechanical interactions to achieve nonlinearities surpassing those of extreme terrestrial flows. Measurements reveal wave steepening, shock fronts, and solitary wave fission—nonlinear behaviors predicted in superfluid helium but never directly observed. Our approach enables lithography-defined wave flume geometries, optomechanical control of hydrodynamic properties, and orders-of-magnitude faster measurements than terrestrial flumes. This approach combining quantum fluids and nanophotonics provides a platform to explore complex wave dynamics at the microscale.