A group of scientists have recently studied quantum turbulence and discovered how energy is lost in the process. Dr. Samuli Autti from Lancaster University worked with researchers from Aalto University on this project, which looked at turbulence on all levels – from tiny things to big places like planets.
A team of researchers have discovered a way to move energy from big scales to small scales. This was predicted by scientists before, and now the findings are published in a scientific journal called Nature Physics. Dr. Autti said that this discovery will become an important part of understanding large quantum systems.
It’s hard to simulate turbulence at bigger sizes (like around airplanes or ships). But when you look at smaller sizes, the turbulence in quantum fluids is different than regular turbulence. This is because the fluid gets focused into specific, line-shaped “centers of flow” called vortices and only takes certain values— which are numbers that can’t be divided any further.
Quantum turbulence is easier to understand and capture in theories because it has a lot of detail. Scientists think that by better understanding quantum turbulence, they can also figure out how classical (typical) turbulence works. In the future, this knowledge could help engineers create things that control water and air flow more accurately.
Dr Jere Mäkinen from Aalto University, the main researcher of this study, said: “Our research with the simple components of turbulence could help us understand how different sizes interact with each other in turbulence better.”
Knowing about classical fluids can help us with many useful things like making vehicles more aerodynamic, predicting the weather better, and controlling the water flow in pipes. Figuring out macroscopic turbulence gives us lots of new possibilities for these real-world uses. Dr. Autti also mentioned that quantum turbulence is a difficult challenge for scientists to study.
Scientists have been trying to discover quantum turbulence around a single vortex for many years, but they haven’t had any success yet. People study this type of turbulence using special substances like atomic gases and fluids that act strangely in cold temperatures. This strange behavior is called the Kelvin wave cascade.
This research has shown that the mechanism we were looking for actually works! This is really important to understanding how big quantum systems work.
A group of scientists, led by Senior Scientist Vladimir Eltsov, did research on the turbulence in a certain type of gas called Helium-3. To do this, they used an ultra-low temperature refrigerator in the Low Temperature Laboratory at Aalto. They found that at a very small level, certain waves that are called Kelvin waves push energy to smaller and smaller areas until it reaches a point where energy gets lost or dissaped.
Dr. Jere Mäkinen from Aalto University said that they have come up with an experimental set-up which could finally answer the question of how energy goes away from spinning vortices (quantized vortices) at super cold temperatures (ultra-low temperatures). With this experiment, there is now a proof that what scientists theorised about these vortices (Kelvin waves transferring energy to smaller parts) actually exists.
Their next goal is to try and control or change a single vortex using devices as small as nanometers, which will be placed inside fluids that don’t freeze easily.
This article is called, “Rotating quantum wave turbulence”. It was written by J. T. Mäkinen, S. Autti, P. J. Heikkinen, J. J. Hosio, R. Hänninen, V. S. L’vov, P. M. Walmsley, V. V Zavjalov and V B Eltsov in March 2023 and is published in Nature Physics magazine: the DOI for it is 10.1038/s41567-023-01966-z .
