As far as quantum turbulence is concerned, scientists have displayed how energy disappears, thereby setting the stage for improved knowledge of turbulence in scales ranging from the microscopic to the planetary.
The researchers used a unique rotating cryostat in their study. Image Credit: © Mikko Raskinen/Aalto University
Dr. Samuli Autti from Lancaster University is one of the authors of a new study on quantum wave turbulence performed collectively with scientists at Aalto University.
The study outcomes of the group have illustrated a new insight into how wave-like motion shifts energy from macroscopic to microscopic length scales, and their outcomes verify a theoretical prediction regarding how the energy has been dissipated at small scales.
The study has been reported in the Nature Physics journal.
Dr. Autti stated, “This discovery will become a cornerstone of the physics of large quantum systems.”
It is hard to stimulate quantum turbulence at large scales, like turbulence near moving ships or airplanes. At small scales, quantum turbulence is distinct from classical turbulence since the turbulent flow of a quantum fluid is restricted next to line-like flow centers known as vortices, and can only become certain quantized values.
This granularity is responsible for making quantum turbulence considerably simpler to capture in theory. It is thought that mastering quantum turbulence will assist physicists in comprehending classical turbulence too.
An enhanced understanding of turbulence starting on the quantum level could enable enhanced engineering in domains where the behavior and flow of gases and fluids like water and air is a major question.
Lead author Dr. Jere Mäkinen from Aalto University stated, “Our research with the basic building blocks of turbulence might help point the way to a better understanding of interactions between different length scales in turbulence.
“Understanding that in classical fluids will help us do things like improve the aerodynamics of vehicles, predict the weather with better accuracy, or control water flow in pipes. There is a huge number of potential real-world uses for understanding macroscopic turbulence.”
In experiments, the formation of quantum turbulence around a single vortex has remained elusive for decades despite an entire field of physicists working on quantum turbulence trying to find it.
Dr Samuli Autti, Study Author, Lancaster University
Autti continued, “This includes people working on superfluids and quantum gases such as atomic Bose-Einstein Condensates (BEC). The theorized mechanism behind this process is known as the Kelvin wave cascade.
“In the present manuscript we show that this mechanism exists and works as theoretically anticipated. This discovery will become a cornerstone of the physics of large quantum systems,” added Autti.
The research group, headed by Senior Scientist Vladimir Eltsov, learned about turbulence in the Helium-3 isotope in a rotating ultra-low temperature refrigerator in the Low-Temperature Laboratory at Aalto.
They discovered that at microscopic scales, alleged Kelvin waves act on separate vortices by constantly pushing energy to smaller and smaller scales—eventually resulting in the scale at which dissipation of energy occurs.
The question of how energy disappears from quantized vortices at ultra-low temperatures has been crucial in the study of quantum turbulence. Our experimental set-up is the first time that the theoretical model of Kelvin waves transferring energy to the dissipative length scales has been demonstrated in the real world.
Dr. Jere Mäkinen, Study Lead Author, Aalto University
The next difficulty is to handle a single quantized vortex with the help of the nano-scale devices that have been submerged in superfluids.
Journal Reference:
Mäkinen, J. T., et al. (2023) Rotating quantum wave turbulence. Nature Physics. doi.org/10.1038/s41567-023-01966-z.