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Bose-Einstein condensates (BECs)
are a quantum state of dilute atomic
gases of weakly interacting bosons
confined in an external potential
and cooled to temperatures near
absolute zero. We consider Gross-Pitaeviskii
Equation (GPE), which is a variant
of the Nonlinear Schoroedinger Equation
(NLSE), to describe the dynamics
of vortices in one-component BECs.
By expressing a solution of the
wave function in polar coordinate,
an ordinary differential equation
(ODE) is obtained, which is a well
known vortex amplitude profile.
This ODE is solved numerically and
we use this numerically solved vortex
profile to sit vortices on BECs.
In order to solve GPE, we use 2nd
order central finite difference
scheme for spatial derivation and
4th order Runge-Kutta method to
integrate in time. With different
external potential, we observe different
dynamics of vortices in BECs. With
an infinite plane potential with
a certain angle, the gradient of
the field initiates vortex dynamics
and a vortex moves in perpendicular
to the gradient of the field. When
the plane potential has no angle
and have two vortices sitting on
BECs, the change of phase and density
difference in background initiate
vortex dynamics. If they have same
charge, they move around in circular
motion; whereas, if they have opposite
charge, they move in parallel to
each other. With a magnetic trap,
we use Thomas-Fermi (TF) limit (ie.
Large atom number limit) to approximate
the background density of the BEC.
In this case, the gradient of the
field initiates the precession of
a vortex orbiting about the center
of TF cloud. Our computational analysis
observes all different vortex dynamics,
and it confirms and supports theoretical
analysis that has been done previously.
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