arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1905.04584cond-mat.quant-gasnlin.PSphysics.optics
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环几何中二元凝聚体的不混溶态和混溶态

Immiscible and miscible states in binary condensates in the ring geometry

Zhaopin Chen, Yongyao Li, Nikolaos P. Proukakis, Boris A. Malomed

摘要:

本文详细研究了具有排斥相互作用的二元原子玻色-爱因斯坦凝聚体中混合模和去混合模的存在性和稳定性。这种状态的稳定性检查通过本征值谱的小扰动,产生的Bogoliubov-德Gennes方程,并直接验证了模拟的基础上耦合的Gross-Pitaevskii方程,不同的物种间和物种内的散射长度,以探测整个范围内的可伸缩性-不可伸缩性过渡。在一维(1D)环的极限中,即,一个很窄的,混合态的稳定性分析研究,包括隐涡(HV)模式,即,两个分量的涡度相反且总角动量为零的那些。考虑到分层的1D状态揭示,除了稳定的复合单峰结构,双峰和三峰的,在一定的粒子数阈值以上。在2D环形几何中,稳定的分层状态存在于径向和方位角配置。我们发现,稳定的径向分层状态可以携带任意的涡度,反直觉,涡度的增加增强了这种状态的稳定性,而不稳定的演变成随机振荡的角分层模式。在二维几何中考虑HV态扩展了径向分层态的稳定范围。

英文摘要:

We report detailed investigation of the existence and stability of mixed and demixed modes in binary atomic Bose-Einstein condensates with repulsive interactions in a ring-trap geometry. The stability of such states is examined through eigenvalue spectra for small perturbations, produced by the Bogoliubov-de Gennes equations, and directly verified by simulations based on the coupled Gross-Pitaevskii equations, varying inter- and intra-species scattering lengths so as to probe the entire range of miscibility-immiscibility transitions. In the limit of the one-dimensional (1D) ring, i.e., a very narrow one, stability of mixed states is studied analytically, including hidden-vorticity (HV) modes, i.e., those with opposite vorticities of the two components and zero total angular momentum. The consideration of demixed 1D states reveals, in addition to stable composite single-peak structures, double- and triple-peak ones, above a certain particle-number threshold. In the 2D annular geometry, stable demixed states exist both in radial and azimuthal configurations. We find that stable radially-demixed states can carry arbitrary vorticity and, counter-intuitively, the increase of the vorticity enhances stability of such states, while unstable ones evolve into randomly oscillating angular demixed modes. The consideration of HV states in the 2D geometry expands the stability range of radially-demixed states.

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