标题： 不可混溶的两组分玻色-爱因斯坦凝聚体超出平均场近似：相变和旋转响应 显示英文标题

标题： Immiscibile two-component Bose Einstein condensates beyond mean-field approximation: phase transitions and rotational response

摘要： 我们考虑一个具有主导的组内排斥密度-密度相互作用的两组分不混溶玻色-爱因斯坦凝聚体。 在该系统的基态相中，只存在一个凝聚体。 这可以看作是$\mathbb{Z}_2$对称性的自发破缺。 我们研究了该系统在有限温度下超越平均场近似的情况下的相图。 在没有旋转的情况下，我们表明，随着温度的升高，系统会从这种基态经历一级相变转变为可混溶的两组分正常流体。 在有旋转的情况下，系统表现出涡旋-涡旋相互作用与短程密度-密度相互作用之间的竞争。 这导致了一个在空间非均匀状态下额外破缺$\mathrm{U}(1)$对称性的旋转驱动“混合”相变。 该状态中的热涨落导致了向列型的两组分涡旋液体薄层。 在组间相互作用足够强时，我们发现超流相和$\mathbb{Z}_2$相变会分裂。 这导致形成一个仅破缺$\mathbb{Z}_2$对称性的中间态。 它代表了密度不平衡的两组分相分离的正常流体。 显示英文摘要

摘要： We consider a two-component immiscible Bose-Einstein condensate with dominating intra-species repulsive density-density interactions. In the ground-state phase of such a system only one condensates is present. This can be viewed as a spontaneous breakdown of $\mathbb{Z}_2$ symmetry. We study the phase diagram of the system at finite temperature beyond mean-field approximation. In the absence of rotation, we show that the system undergoes a first order phase transition from this ground state to a miscible two-component normal fluid as temperature is increased. In the presence of rotation, the system features a competition between vortex-vortex interaction and short range density-density interactions. This leads to a rotation-driven "mixing" phase transition in a spatially inhomogeneous state with additional broken $\mathrm{U}(1)$ symmetry. Thermal fluctuations in this state lead to nematic two-component sheets of vortex liquids. At sufficiently strong inter-component interaction, we find that the superfluid and $\mathbb{Z}_2$ phase transitions split. This results in the formation of an intermediate state which breaks only $\mathbb{Z}_2$ symmetry. It represents two phase separated normal fluids with density imbalance.