New mechanism found for generating giant vortices in quantum fluids of light

Anyone who has drained a bathtub or stirred cream into coffee has seen a vortex, a ubiquitous formation that appears when fluid circulates. But unlike water, fluids governed by the strange rules of quantum mechanics have a special restriction: as was first predicted in 1945 by future Nobel winner Lars Onsager, a vortex in a quantum fluid can only twist by whole-number units.