Microscopic ‘ocean’ on a chip reveals new nonlinear wave behavior

University of Queensland researchers have created a microscopic “ocean” on a silicon chip to miniaturize the study of wave dynamics. The device, made at UQ’s School of Mathematics and Physics, uses a layer of superfluid helium only a few millionths of a millimeter thick on a chip smaller than a grain of rice.

The work is published in the journal Science.

Dr. Christopher Baker said it was the world’s smallest wave tank, with the quantum properties of superfluid helium allowing it to flow without resistance, unlike classical fluids such as water, which become immobilized by viscosity at such small scales.

“The study of how fluids move has fascinated scientists for centuries because hydrodynamics governs everything from ocean waves and the swirl of hurricanes to the flow of blood and air through our bodies,” Dr. Baker said. “But a lot of the physics behind waves and turbulence has been a mystery.

“Using laser light to both drive and measure the waves in our system, we have observed a range of striking phenomena. We saw waves that leaned backward instead of forward, shock fronts, and solitary waves known as solitons which traveled as depressions rather than peaks. This exotic behavior has been predicted in theory but never seen before.”

Professor Warwick Bowen said the chip-scale approach in the Queensland Quantum Optics Laboratory could compress the duration of experiments a millionfold, reducing days of data collection to milliseconds.

“In traditional laboratories, scientists use enormous wave flumes up to hundreds of meters long to study shallow-water dynamics such as tsunamis and rogue waves,” Professor Bowen said. “But these facilities only reach a fraction of the complexity of waves found in nature.

“Turbulence and nonlinear wave motion shape the weather, climate, and even the efficiency of clean-energy technologies like wind farms. Our miniature device amplifies the nonlinearities that drive these complex behaviors by more than 100,000 times. Being able to study these effects at chip scale—with quantum-level precision—could transform how we understand and model them.”

Professor Bowen said the UQ development opens a path to programmable hydrodynamics, explaining, “Because the geometry and optical fields in this system are manufactured using the same techniques as those used for semiconductor chips, we can engineer the fluid’s effective gravity, dispersion, and nonlinearity with extraordinary precision.

“Future experiments could use the technology to discover new laws of fluid dynamics and accelerate the design of technologies ranging from turbines to ship hulls. Experiments on this tiny platform will improve our ability to predict the weather, explore energy cascades and even quantum vortex dynamics—questions central to both classical and quantum fluid mechanics.”