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Abstracts
P3.24
Circulation and Vortices in Rotating Superfluid Helium 4 Confined
in a Ring
Makiuchi, T.(1), Murakawa, S.(2), Shirahama K.(1)
(1) Keio University, Faculty of Science and Technology, Department of Physics,
Yokohama, 223-8522, Japan (2) University of Tokyo, Cryogenics Research Center,
Bunkyo, 113-0032, Japan
We investigated the circulation and quantum vortices in a rotating superfluid
4
He confined in a ring. A torsional oscillator with a torus cavity and a superleak
separation was used to produce and to detect a standing wave of second sound in
circumferential direction. It is known that the second sound velocity is decreased
in the presence of vortices due to the mutual friction (Miller et al., PRB, 17 1035
(1978)). We observed a hysteresis in second sound velocity versus rotation angular
velocity from 0 to 2.5 rad/s. This implies vortices are (meta-)stable even at zero
angular velocity for a couple of days. An analogy to type-II superconductors and
a stability of vortices are discussed.
P3.25
Theoretical analysis for mobility of ions below a free surface of
3
He-B
Yasumasa Tsutsumi
Department of Basic Science, The University of Tokyo
At a surface of the superfluid
3
He-B, Majorana fermions emerge as the surface
bound state. Observation of the surface bound state was attempted via mobility
of ions below a free surface [1]. Although the observed mobility is suppressed
than that in the bulk B-phase at low temperatures, it is independent of the
trapped depth which is shorter than the coherence length. Then, it has not been
clear whether the experiment could observe the surface bound state. In this
presentation, I will show that the mobility of ions below a free surface, at which
quasiparticles are specularly reflected, does not so much depend on the depth
within the coherence length. Therefore, I conclude that the experiment observed
the ideal surface bound state with linear dispersion.
[1] H. Ikegami et al., J. Phys. Soc. Jpn. 82, 124607 (2013).
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