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arXiv 1608.03300cond-mat.quant-gas
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布居不平衡双组分玻色-爱因斯坦凝聚体中的竞争相互作用

Competing interactions in population-imbalanced two-component Bose-Einstein condensates

Peder N. Galteland, Asle Sudbø

摘要:

我们考虑了二维的两组分玻色-爱因斯坦凝聚体,有和没有合成的“自旋-轨道”相互作用。密度和相位波动的冷凝物包括在内,使我们能够研究热波动和密度-密度相互作用的物理起源与自旋-轨道相互作用的影响。在没有自旋轨道相互作用的情况下,我们发现组分间的密度相互作用耗尽少数凝聚。热驱动的相变是由耦合密度和相位波动驱动的,但无论少数和多数凝聚体是否存在于基态中,或仅存在一种凝聚体,都被证明是具有接近普遍振幅比的Kosterlitz-无偏普适性类中的相变。在存在自旋-轨道相互作用的情况下,我们观察到三个独立的阶段,这取决于自旋-轨道耦合和组分间密度-密度相互作用的强度:对于小的组分间相互作用,具有均匀振幅的相位调制相位,对于中等自旋-轨道耦合强度和足够大的组分间相互作用,以及相位调制的\textit{and}振幅调制的相位,用于足够大的自旋-轨道耦合和组分间密度-密度相互作用的值。观察到仅由单个$\bv q$ -矢量调制的相通过具有周期性边界条件的强脱钉转变转变为各向同性液体,该脱钉转变随着开放边界而减弱。

英文摘要:

We consider a two-component Bose-Einstein condensate with and without synthetic "spin-orbit" interactions in two dimensions. Density- and phase-fluctuations of the condensate are included, allowing us to study the impact of thermal fluctuations and density-density interactions on the physics originating with spin-orbit interactions. In the absence of spin-orbit interactions, we find that inter-component density interactions deplete the minority condensate. The thermally driven phase transition is driven by coupled density and phase-fluctuations, but is nevertheless shown to be a phase-transition in the Kosterlitz-Thouless universality class with close to universal amplitude ratios irrespective of whether both the minority- and majority condensates exist in the ground state, or only one condensate exists. In the presence of spin-orbit interactions we observe three separate phases, depending on the strength of the spin-orbit coupling and inter-component density-density interactions: a phase-modulated phase with uniform amplitudes for small intercomponent interactions, a completely imbalanced, effectively single-component, condensate for intermediate spin-orbit coupling strength and suficciently large inter-component interactions, and a phase-modulated \textit{and} amplitude-modulated phase for sufficiently large values of both the spin-orbit coupling and the inter-component density-density interactions. The phase which is modulated by a single $\bv q$-vector only is observed to transition into an isoptropic liquid through a strong de-pinning transition with periodic boundary conditions, which weakens with open boundaries.

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