Quantum vortices experience friction after all
Images of an ultracold gas of lithium‑6 atoms confined in a cylindrical optical trap. A quantum vortex pinned by a laser beam is visible in the centre. A second vortex, not held in place, can move freely; in the example shown, it orbits around the central vortex. If friction is present in the system, the radius of this orbit gradually decreases. Illustration taken from the publication
A publication offering a new perspective on the dynamics of quantum vortices in a superfluid atomic gas has appeared in the prestigious journal Nature Communications. Researchers from the Faculty of Physics at the Warsaw University of Technology were involved in the work.
An international team of researchers, including both experimentalists and theorists, among them Prof. Piotr Magierski and Gabriel Wlazłowski, PhD, from the Faculty of Physics at the Warsaw University of Technology, published in Nature Communications the latest results on the dynamics of quantum vortices in a strongly interacting superfluid atomic gas (^6Li). The paper presents the first direct measurements of the parameters describing the frictional force acting on a moving quantum vortex, generated by the surrounding medium.
Using one of Europe’s largest supercomputers, LUMI, researchers from WUT carried out advanced numerical simulations. The calculations were based on the theoretical approach to describing superfluid quantum systems in nonequilibrium states, which is being developed at the Faculty of Physics as well as on dedicated software created within the Nuclear Theory Group.
The theoretical results obtained showed exceptionally good agreement with the experimental data, which was confirmed by the collaborating experimental group. This convergence made it possible to gain a detailed understanding of the mechanisms responsible for the emergence of dissipative effects in superfluid quantum systems, that is, under conditions in which their presence had not previously been obvious.
“The publication in Nature Communications confirms the well-established international standing of the team from the Faculty of Physics at the Warsaw University of Technology as one of the world’s leaders in research on the dynamics of superfluid quantum systems,” emphasises Prof. Magierski.
This discovery significantly broadens our understanding of quantum hydrodynamics and has far‑reaching implications, from explaining the properties of ultracold atomic gases to modelling the matter inside neutron stars, where the existence of superfluid material containing quantum vortices is also predicted. The results represent an important step towards a complete and coherent description of transport phenomena in strongly correlated quantum systems.
The full article, “Mutual friction and vortex Hall angle in a strongly interacting Fermi superfluid”, is available at www.nature.com.