Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mesoscopics of half-quantum vortex pair deconfinement in a trapped
  spin-one condensate   Motivated by a recent experiment in an antiferromagnetic spin-1 Bose-Einstein
condensate of ${}^{23} \textrm{Na}$ atoms, we study the energetical stability
of a singly quantum vortex injected into the center of a quasi-two-dimensional
gas with zero total spin against dissocation into a pair of half-quantum
vortices. We find that the critical dissociation point of this
confinement-deconfinement type phase transition can be expressed in terms of
the ratio of density-density ($c_0$) and spin-spin ($c_2$) coupling constants.
The transition of bound to unbound vortices, in particular, sensitively depends
on (1) the ratio of system size ($R$) to density healing length ($\xi_d$), and
(2) the trap potential. Specifically, the critical ratio $(c_2 /
c_0)_{\textrm{cr}}$ increases when $R / \xi_d$ decreases, and is relatively
larger in a harmonic trap than in a box trap. Dissociation is energetically
generally favored for $c_2 / c_0 < (c_2 / c_0)_{\textrm{cr}}$, which as a
corollary implies that vortex dissociation is observed as well for negative
$c_2 < 0$, e.g., in a rubidium spin-1 BEC, whereas in a sodium spin-1 BEC
($c_2>0$) it is energetically blocked above the critical ratio $(c_2 /
c_0)_{\textrm{cr}}$. Tuning the coupling ratio $c_2/c_0$ by using microwave
control techniques, the dependence of the deconfinement phase transition on
coupling parameters, density, and system size we predict, can be verified in
experiments with ultracold spinor gases.

22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an