Berlin 2018 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 77: Focus Session: Quantum Turbulence and Imaging of Quantum Flow of Superfluids
TT 77.3: Invited Talk
Thursday, March 15, 2018, 10:30–11:00, H 0104
Visualising Pure Quantum Turbulence in Fermionic Superfluid — •Viktor Tsepelin — Lancaster University, Lancaster, UK
In this talk, we present experimental and numerical studies of pure quantum turbulence in superfluid 3He-B. While the flow of bulk superfluid must be irrotational, it can mimic classical turbulence by supporting singly quantised vortices. Due to the absence of friction at the lowest temperatures, quantum turbulence is significantly simpler to model than classical turbulence. We demonstrate that, despite stringent requirements to reach one ten-thousandth of a degree from absolute zero, superfluid 3He contains everything required for the generation and study of quantum turbulence. For instance, we do not need to add small tracer particles to visualise turbulence, since the existing ambient thermal excitations, ballistic quasiparticles, can play that role. We explain how to use these ballistic quasiparticles to image vortex tangles produced by a mechanical agitation of the superfluid at velocities above critical. Next we discuss, numerical simulations of a realistic 3D vortex tangle and propagation of quasiparticles through it. This simulation validates the experimental visualization of turbulence and highlights interesting properties of pure quantum turbulence.
The author thanks S. Ahlstrom, A. Baggaley, C.F. Barenghi, D.I. Bradley, S.N. Fisher, E.A. Guise, R. Haley, M. Jackson, G.R. Pickett, Y. Sergeev, N.G. Suramlishvili and A. Woods for collaboration.