Coherent vortex structures in quantum turbulence

Quantum turbulence, easily generated in superfluid helium, consists of a disordered tangle of thin, discrete vortex lines of quantised circulation which move in a fluid without viscosity. In this report we show that, in very intense quantum turbulence, the vortex tangle contains small coherent vortical structures (bundles of quantised vortices) which arise from the fundamental Biot-Savart interaction between vortices, and which are similar to the intermittent, coherent structures ("worms") observed in ordinary viscous turbulence. Our result highlights the similarity between quantum turbulence and ordinary turbulence, and sheds new light into the origin of the "worms" in ordinary turbulence