Immiscible and miscible states in binary condensates in the ring geometry
Immiscible and miscible states in binary condensates in the ring geometry
复制标题
环几何中二元凝聚体的不混溶和混溶状态
DOI：
10.1088/1367-2630/ab3207
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发表时间：
2019
影响因子：
3.3
通讯作者：
Malomed Boris A.
中科院分区：
文献类型：
--
作者：
Chen Zhaopin;Li Yongyao;Proukakis Nikolaos P.;Malomed Boris A.
我们报告了在环形陷阱几何中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和解混模式的存在和稳定性的详细研究。这种状态的稳定性通过Bogoliubov-de Gennes方程产生的小扰动的特征值谱来检验，并通过基于耦合的Gross-Pitaevskii方程的模拟直接验证，这些方程改变了种间和种内散射长度，从而探测了整个混相-非混相转变的范围。在一维环的极限，即非常窄的环中，分析研究了混合态的稳定性，包括隐藏涡量（HV）模态，即两个分量的涡量相反且总角动量为零的模态。考虑解混一维态，除了稳定的单峰结构外，复合材料的双峰和三峰结构在一定的粒子数阈值以上。在二维环形几何结构中，径向和方位角均存在稳定的脱混状态。我们发现稳定的径向解混态可以携带任意涡量，而且与直觉相反，涡量的增加增强了这种状态的稳定性，而不稳定的状态演变成随机振荡的角度解混模式。二维几何结构中对HV态的考虑扩大了径向解混态的稳定范围。
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, ie a very narrow one, stability of mixed states is studied analytically, including hidden-vorticity (HV) modes, ie 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.