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arXiv 0905.1330cond-mat.quant-gascond-mat.stat-mech
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由光晶格上二组分玻色-爱因斯坦凝聚体的微观参数和激发能计算阻力和超流速度

Calculation of Drag and Superfluid Velocity from the Microscopic Parameters and Excitation Energies of a Two-Component Bose-Einstein Condensate on an Optical Lattice

Jacob Linder, Asle Sudbø

摘要:

我们研究了一个位于光晶格上的二组分玻色-爱因斯坦凝聚体模型。在平均场水平的Bogolioubov方法,我们推导出精确的解析表达式时,考虑到任意站点之间的跳跃和相互作用的激发光谱的两个组件的冷凝物。因此,我们的研究结果构成了一个基础的工程,试图澄清系统中的高阶相互作用的影响。我们调查的激发谱和两个分支的超流速度更详细的两个极限情况下,特别相关。此外,我们还将有效玻色-哈伯德模型中的跃迁参数和相互作用参数与系统中的微观参数,如激光波长和凝聚体中组分的原子质量联系起来。然后,这些结果被用来计算分析和数值的冷凝物的组件之间的阻力系数。我们发现,阻力是最有效的接近组件之间的质量相等的对称情况下,无论组件间的相互作用和晶格阱深度的强度。

英文摘要:

We investigate a model of a two-component Bose-Einstein condensate residing on an optical lattice. Within a Bogolioubov-approach at the mean-field level, we derive exact analytical expressions for the excitation spectrum of the two-component condensate when taking into account hopping and interactions between arbitrary sites. Our results thus constitute a basis for works that seek to clarify the effects of higher-order interactions in the system. We investigate the excitation spectrum and the two branches of superfluid velocity in more detail for two limiting cases of particular relevance. Moreover, we relate the hopping and interaction parameters in the effective Bose-Hubbard model to microscopic parameters in the system, such as the laserlight wavelength and atomic masses of the components in the condensate. These results are then used to calculate analytically and numerically the drag coefficient between the components of the condensate. We find that the drag is most effective close to the symmetric case of equal masses between the components, regardless of the strength of the intercomponent interaction and the lattice well depth.

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