July 6, 2022
Osaka Metropolitan University
Keio University
A research group including Professor Makoto Tsubota and Project Assistant Professor Satoshi Yui (Graduate School of Science and the Nambu Yoichiro Institute of Theoretical and Experimental Physics) of Osaka Metropolitan University, and Professor Hiromitsu Kobayashi (Department of Physics, Hiyoshi Campus, Faculty of Law, Keio University), has worked in collaboration with Wei Guo (Associate Professor) and Yuan Tang (Postdoctoral Associate) of Florida State University. Through theoretical and numerical simulations, they studied the diffusion of quantized vortices in quantum turbulence within superfluid liquid helium-4 (4He) at ultralow temperatures near absolute zero (−273°C). By comparing their findings with experimental results from a previous study by Associate Professor Guo's group, they have revealed that this diffusion follows a specific law. In the current numerical simulations, quantized vortices undergo "superdiffusion," spreading rapidly in the initial stages of diffusion. After a long period, they transition to "normal diffusion," a process also observed in phenomena such as the motion of pollen in still water. This research achievement, with consistent results between experiments and numerical simulations, could be a new step toward understanding complex quantum turbulence. Furthermore, it is expected to lead to further research on diffusion in other quantum systems.
The results of this research were published online in "Physical Review Letters" on July 5, 2022. The paper was also selected as an Editors’ Suggestion, recognizing it as a particularly significant finding.
Please see below for the full press release.