  The collisional and magnetic field quench dynamics of a coupled spin-vortex
pair in dipolar spinor Bose-Einstein condensates in a double well potential are
numerically investigated in the mean field theory. Upon a sudden release of the
potential barrier the two layers of condensates collide with each other in the
trap center with the chirality of the vortex pair exchanged after each
collision, showing the typical signature of in-phase collision for the parallel
spin vortex phase, and out-of-phase collision for the antiparallel phase. When
quenching the transverse magnetic field, the vortex center in the
single-layered condensate starts to make a helical motion with oval-shaped
trajectories and the displacement of the center position is found to exhibit a
damped simple harmonic oscillation with an intrinsic frequency and damping
rate. The oscillation mode of the spin vortex pair may be tuned by the initial
magnetic field and the height of the Gaussian barrier, e.g. the gyrotropic
motions for parallel spin vortex pair are out of sync with each other in the
two layers, while those for the antiparallel pair exhibit a
double-helix-structure with the vortex centers moving opposite to each other
with the same amplitude.
