Nonlinear Effects of Collective Excitation of a Trapped Bose-Einstein Condensate

T. Kimura, Hiroki Saito, Masahito Ueda

Guan-Qiang Li, Libin Fu, Ju-Kui Xue +2 more

We investigate the collective excitations of a one-dimensional Bose-Einstein condensate with repulsive interaction between atoms in a quadratic plus quartic trap. Using variational approaches, the coupled equations of motions for the center-of-mass coordinate of the condensate and its width are derived. Then, two low-energy excitation modes are obtained analytically. The frequency shift induced by the anharmonic distortion, and the collapse and revival of the collective excitations originating from the nonlinear coupling between the two modes, are discussed.

Xue Ju-Kui

It is investigated that the collective excitations of a one-dimensional Bose-Einstein condensate(BEC) with repulsive interaction between atoms in a quadratic plus quartic trap V(x)=12(x~2+λx~4).By using the variational approach,the analytical expressions are derived for two low-energy collective modes,and the effect of the anharmonicity of the potential trap on BEC collective excitations is studied.When(λ0) the frequencies will be blue shifted and when λ0 the frequencies will be red shifted.Meanwhile,the variations of the center-of-mass of the condensate and its width under different values of the driving amplitude are discussed.It is found that the two modes couple each other due to the anharmonicity,and the beating structure for the variation of the width occur.Finally,the response result corresponding to the frequency driving is given.

Yeong E. Kim, Alexander L. Zubarev

Yong-li Ma, S. T. Chui, John C. Kimball

P.D. Anoop, R. B. Thayyullathil

Using variational method, the wave function of a quasi two-dimensional Bose—Einstein Condensate in an anharmonic trap is analyzed and the influence of gravity on the collective excitations is studied. It is found that the effect of gravity on the condensate has got crucial dependence on the anharmonicity of the trap.