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.