Applying a bi-local mean field approximation to the fractional quantum Hall
state of ν=1/3, we obtain charged and neutral vortex mean field solutions
numerically. We calculate the mean field energy and the fluctuation
corrections. The charged vortex has a fractional charge and a fractional
angular momentum. The neutral vortex is a bound state of two charged vortices
and has a zero charge and a zero angular momentum. The creation energy of the
neutral vortex is about a half of the pair creation energy of two charged
vortices. The magnetic field dependence of the gap energy agrees with the
Laughlin's quasiparticle gap energy.Comment: 22 pages, EPHOU-94-001, 8 figures available as a hard copy via
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