Browsing by Author "Kao, Yee-Mou"

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Band structures of a dipolar Bose-Einstein condensate in one-dimensional lattices
(2008-08-01)
Lin, YuanYao
;
Lee, Ray-Kuang
;
Kao, Yee-Mou
;
Jiang, Tsin-Fu
;
物理研究所
We derive the effective Gross-Pitaevskii equation for a cigar-shaped dipolar Bose-Einstein condensate in one-dimensional lattices and investigate the band structures numerically. Due to the anisotropic and the long-ranged dipole-dipole interaction in addition to the known contact interaction, we elucidate the possibility of modifying the band structures by changing the alignment of the dipoles with the axial direction. With the considerations of the transverse parts and the practical physical parameters of a cigar-shaped trap, we show the possibility to stabilize an attractive condensate simply by adjusting the orientation angle of dipoles. Some interesting Bloch waves at several particle current densities are identified for possible experimental observations.
Transition temperature of the interacting dipolar Bose gas
(2007-03-01)
Kao, Yee-Mou
;
Jiang, T. F.
;
物理研究所
;
Institute of Physics
We investigate the effects of long-ranged dipole-dipole potential on the transition temperature of a weakly interacting Bose gas. We apply the two-fluid model to derive the energy spectra of the thermal and the condensate parts. From the interaction modified spectra of the system, the formula for the shift of transition temperature was derived. Compared to the conventional weakly interacting Bose system with contact potential only where thermal effect is larger, we find that the condensate effect is about two times that of the thermal part in the dipolar system. Due to the relative smallness of dipole-dipole interaction with respect to the contact interaction in current dipolar Bose-Einstein condensation, we suggest to measure the dipolar effect by tuning the scattering length to negligible small by the Feshbach resonance technique.