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Abstracts
I4.4
Dynamics of half-quantum vortices in a spinor Bose-Einstein
condensate
Y. Shin(1,2), S. W. Seo(1)
1) Department of Physics and Astronomy, Seoul National University, Seoul
08826, Korea
2) Center for Correlated Electron Systems, Institute for Basic Science, Seoul
08826, Korea
Quantum vortices with half the quantum circulation, known as half-quantum
vortices (HQVs), have been observed in various spinor superfluid systems recently.
In this presentation, we describe our recent experimental studies of HQV dynamics
in a spin-1 antiferromagnetic Bose-Einstein condensate, where we observe the
spontaneous dissociation of a singly charged vortex into a pair of HQVs and
the collisional dynamics of HQV pairs, revealing the short range interactions
arising from their ferromagnetic cores. Additionally, we investigate the relaxation
dynamics of turbulent superflow containing many HQVs to find that spin waves
are generated by the collisional motions of the HQVs.
O4.7
Quantized vortices following reconnections
Fonda Enrico(1), Sreenivasan Katepalli R.(2), Lathrop Daniel P.(3)
1) New York University, Physics Department, New York , New York 10012,
USA
2) New York University, Departments of Physics and Mechanical Engineering
and the Courant Institute of Mathematical Sciences, New York , New York
10012, USA
3) University of Maryland, Department of Physics, Department of Geology,
Institute for Research in Electronics and Applied Physics, and Center for
Nanophysics and Advanced Materials, College Park, Maryland 20742, USA
We visualized quantized vortex reconnections in superfluid
4
He using sub-micron
frozen air tracers. Compared to previous work, the fluid was almost at rest
leading to fewer, straighter, slower-moving vortices. This condition allowed us
to observe the propagation of Kelvin waves and to characterize the influence of
the inter-vortex angle on the evolution of the recoiling vortices. The agreement
of the experimental data to the analytical and numerical models suggests that
the dynamics of the reconnection of long straight vortices on the scale of these
experiments can be described by the self-similar solutions of the local induction
approximation or Biot-Savart equations.
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