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arXiv 1204.1256cond-mat.quant-gasquant-ph
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用约束法控制二元玻色-爱因斯坦凝聚体的相分离

Controlling phase separation of a two-component Bose-Einstein condensate by confinement

L. Wen, W. M. Liu, Yongyong Cai, J. M. Zhang, Jiangping Hu

备注：
8 pages, 2 figures
发表信息：
Phys. Rev. A 85, 043602 (2012)
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摘要：

我们指出，当考虑动能时，普遍接受的两组分玻色-爱因斯坦凝聚体相分离的条件g11 g22 <g122是不够的，它与组分间相互作用竞争，有利于相混合.这里g11、g22和g12分别是组分内和组分间相互作用强度。以宽度为L的d维无限深方势阱为例，简单的标度分析表明，当d=1（d=3）时，无论g11 g22 <g122是否满足，相分离都将被抑制为L \rightarrow 0（L \rightarrow \infty）.在d=2的中间情况下，宽度L是无关紧要的，但是即使g11 g22 <g122，也可以部分地或甚至完全地抑制相分离。此外，动能的作用使相变从一级相变变为二级相变。所有这些结果都可以推广到d维谐振势，其中谐振子长度λ ho扮演L的角色。我们的发现提供了一种通过改变约束来控制双组分凝聚体的可压缩性-不可压缩性转变的方案，而不是改变g值的传统方法。

英文摘要：

We point out that the widely accepted condition g11g22<g122 for phase separation of a two-component Bose-Einstein condensate is insufficient if kinetic energy is taken into account, which competes against the intercomponent interaction and favors phase mixing. Here g11, g22, and g12 are the intra- and intercomponent interaction strengths, respectively. Taking a d-dimensional infinitely deep square well potential of width L as an example, a simple scaling analysis shows that if d=1 (d=3), phase separation will be suppressed as L\rightarrow0 (L\rightarrow\infty) whether the condition g11g22<g122 is satisfied or not. In the intermediate case of d=2, the width L is irrelevant but again phase separation can be partially or even completely suppressed even if g11g22<g122. Moreover, the miscibility-immiscibility transition is turned from a first-order one into a second-order one by the kinetic energy. All these results carry over to d-dimensional harmonic potentials, where the harmonic oscillator length ξho plays the role of L. Our finding provides a scenario of controlling the miscibility-immiscibility transition of a two-component condensate by changing the confinement, instead of the conventional approach of changing the values of the g's.

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