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Center motions of nonoverlapping condensates coupled by long-range dipolar interaction in bilayer and multilayer stacks
We investigate the effect of anisotropic and long-range dipole-dipole
interaction (DDI) on the center motions of nonoverlapping Bose-Einstein
condensates (BEC) in bilayer and multilayer stacks. In the bilayer, it is shown
analytically that while DDI plays no role in the in-phase modes of center
motions of condensates, out-of-phase mode frequency () depends
crucially on the strength of DDI (). At the small- limit,
. In the multilayer stack, transverse
modes associated with center motions of coupled condensates are found to be
optical phonon like. At the long-wavelength limit, phonon velocity is
proportional to .Comment: 7 pages, 5 figure
Using modified Gaussian distribution to study the physical properties of one and two-component ultracold atoms
Gaussian distribution is commonly used as a good approximation to study the
trapped one-component Bose-condensed atoms with relatively small nonlinear
effect. It is not adequate in dealing with the one-component system of large
nonlinear effect, nor the two-component system where phase separation exists.
We propose a modified Gaussian distribution which is more effective when
dealing with the one-component system with relatively large nonlinear terms as
well as the two-component system. The modified Gaussian is also used to study
the breathing modes of the two-component system, which shows a drastic change
in the mode dispersion at the occurrence of the phase separation. The results
obtained are in agreement with other numerical results.Comment: 7 pages, 7 figures, accepted for publication in Phys. Rev.
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