Along with scientists from Aalto University, Dr. Samuli Autti of Lancaster University co-authored a recent paper on quantum wave turbulence. The research team’s discoveries, which were reported in Nature Physics, show a new understanding of how wave-like motion transmits energy from macroscopic to microscopic length scales. Also, their findings support a theoretical assumption regarding how the energy is lost at small sizes. “This discovery will become a cornerstone of the physics of big quantum systems,” Dr. Autti said.

Simulating quantum turbulence at large sizes, such as the turbulence around moving ships or airplanes, is challenging. Because a quantum fluid’s turbulent flow is constrained by vortices, which are line-like flow centers, and can only assume specific, quantized values, quantum turbulence differs from classical turbulence at small scales. It is commonly accepted that knowing quantum turbulence will aid physicists in understanding conventional turbulence as well because of how much simpler it is to conceptualize in a theory due to its granularity.

Future advancements in engineering could be made possible by a better knowledge of turbulence, starting at the quantum level, in fields where the flow and behavior of fluids and gases like water and air are crucially important. “Our research with the basic constituents of turbulence might help light the way to a better understanding of interactions between different length scales in turbulence,” stated the study’s lead author, Dr. Jere Mäkinen of Aalto University. It will be easier for us to control water flow in pipes, make more accurate weather predictions, and improve the aerodynamics of cars if we have a better understanding of classical fluids. Understanding macroscopic turbulence has a plethora of possible real-world applications.

According to Dr. Autti, quantum turbulence presents a difficult difficulty for physicists. “In experiments, the production of quantum turbulence around a single vortex has remained elusive for decades despite a whole field of scientists working on quantum turbulence seeking to locate it. This includes those who study with quantum gases including atomic Bose-Einstein Condensates and superfluids (BEC). The Kelvin wave cascade is the proposed mechanism for this phenomenon. In the current publication, we demonstrate that this mechanism actually exists and functions as predicted by theory. This finding will be fundamental to understanding large-scale quantum systems.

The team of researchers from Aalto University, under the direction of Senior Scientist Vladimir Eltsov, investigated turbulence in the Helium-3 isotope in a special rotating ultra-low temperature refrigerator. They discovered that at tiny scales, so-called Kelvin waves act on individual vortices by continuously driving energy to lower scales, ultimately leading to the scale at which energy dissipation takes place. According to Dr. Jere Mäkinen of Aalto University: “The investigation of quantum turbulence has focused heavily on the issue of how energy vanishes from quantized vortices at extremely low temperatures. The theoretical concept of Kelvin waves transmitting energy to the dissipative length scales has never been empirically proven until now, thanks to our experimental setup.” The next task for the group is to control a single quantized vortex with the aid of nano-scale equipment submerged in superfluids.