QFS2016 Book of Abstracts

Abstracts

O4.10

Evolution of a superfluid vortex filament tangle driven by the

Gross-Pitaevskii equation

Villois Alberto(1), Proment Davide(1), Krstulovic Giorgio(2)

1) University of East Anglia, School of Mathematics, Norwich Research Park,

Norwich, NR4 7TJ, United Kingdom

2) Universit´e de la Cˆote d’Azur, CNRS, Observatoire de la Cˆote d’Azur,

Laboratoire J.L. Lagrange, UMR7293, B.P. 4229, 06304 Nice Cedex 4, France

We study the evolution of a vortex filament tangle driven by the Gross-Pitaevskii

equation using a recently developed vortex-tracking algorithm. We observe

the Vinen’s decay law for the vortex line density with a coefficient that

is in quantitative agreement with the values measured in Helium II. We

investigate the properties of the tangle, showing that linked rings may appear

and that local curvature and torsion distributions exhibit large fluctuations and

self-similar dynamics. We obtain the temporal evolution of the Kelvin wave

spectrum providing evidence of the development of a weak-wave turbulence

cascade. Ongoing investigations on reconnections may also be presented.

(arXiv:1605.00567)

O4.11

Graphene resonators in studies of quantum fluids

J.-P. Kaikkonen, A. Savin, A. Laitinen, I. Todoshchenko, and P.J. Hakonen

Low Temperature Laboratory, Department of Applied Physics, Aalto University,

00076 AALTO, Finland

Suspended graphene and carbon nanotube devices are among the most precise

mass, force and charge sensors. We are utilizing these ultrasensitive devices

in investigations of atomic layers and bulk superfluid phases of

He and

He.

In our first experiments we have investigated thin superfluid

He layers on

top of graphene resonators. Shifts of resonance frequency as well as changes

in the resonance structure are found. For reference, we have studied fully

superfluid-immersed graphene resonators. In these experiments, we have also

investigated dynamic behavior of two gold MEMS resonators coupled non-linearly

via graphene. Internal resonances in this coupled system are observed.

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