In a superfluid state at cryogenic temperatures close to absolute zero, liquid-helium-4 has a special vortex called a quantized vortex. This vortex arises from quantum mechanical effects.
Therefore, having a theoretical model to predict the vortex motion reliably promises a broad significance. But a grand challenge in developing such a model is to evaluate the dissipative force caused by thermal quasiparticles in the quantum fluids scattering off the vortex cores. Various models have been proposed, but it remains to be seen which model describes reality due to the lack of comparative experimental data.
In collaboration with colleagues from Florida State University and Keio University, a research team led by Professor Makoto Tsubota and Specially Appointed Assistant Professor Satoshi Yui from the Graduate School of Science and Nambu Yoichiro Institute of Theoretical and Experimental Physics, Osaka Metropolitan University, respectively, investigated numerically the interaction between a quantized vortex and a normal-fluid.
Researchers chose the most reliable theoretical model out of various options based on the experimental findings. They discovered that the model that best fits the practical outcomes combines more accurate mutual friction and considers variations in the normal fluid.
Professor Tsubota said, “The subject of this study, the interaction between a quantized vortex and a normal fluid, has been a great mystery since I began my research in this field 40 years ago. Computational advances have made it possible to handle this problem, and the brilliant visualization experiment by our collaborators at Florida State University has led to a breakthrough. As is often the science case, subsequent developments in technology have made it possible to elucidate, and this study is a good example of this.”
Journal Reference:
- Tang, Y., Guo, W., Kobayashi, H. et al. Imaging quantized vortex rings in superfluid helium to evaluate quantum dissipation. Nature Communications. 14, 2941 (2023). DOI: 10.1038/s41467-023-38787-w