1. Low Temperature Laboratory, Helsinki University of Technology, PO Box 2200, FIN-02015 HUT, Finland
2. Department of Physics, Osaka City University, Sumiyoshi-Ku, Osaka 558-8585, Japan
3. Kamerlingh Onnes Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands
4. Kapitza Institute for Physical Problems, and
5. Landau Institute for Theoretical Physics, Kosygina 2, 119334 Moscow, Russia
6. Joint Low Temperature Laboratory, Institute of Physics ASCR and Charles University, V Holeovikách 2, 180 00 Prague, Czech Republic

Correspondence to: G. E. Volovik^1,5 Correspondence and requests for materials should be addressed to V.E. (Email: ve@boojum.hut.fi).

Abstract

Hydrodynamic flow in classical and quantum fluids can be either laminar or turbulent. Vorticity in turbulent flow is often modelled with vortex filaments. While this represents an idealization in classical fluids, vortices are topologically stable quantized objects in superfluids. Superfluid turbulence¹ is therefore thought to be important for the understanding of turbulence more generally. The fermionic ³He superfluids are attractive systems to study because their characteristics vary widely over the experimentally accessible temperature regime. Here we report nuclear magnetic resonance measurements and numerical simulations indicating the existence of sharp transition to turbulence in the B phase of superfluid ³He. Above 0.60T_c (where T_c is the transition temperature for superfluidity) the hydrodynamics are regular, while below this temperature we see turbulent behaviour. The transition is insensitive to the fluid velocity, in striking contrast to current textbook knowledge of turbulence². Rather, it is controlled by an intrinsic parameter of the superfluid: the mutual friction between the normal and superfluid components of the flow, which causes damping of the vortex motion.