标题： 二元玻色-爱因斯坦凝聚体混溶-不可混溶转变的非线性调控 显示英文标题

标题： Nonlinear management of the miscibility-immiscibility transition in binary Bose-Einstein condensates

摘要： 我们研究了非线性管理（NM，即组分间排斥强度的周期性变化）在两组分BEC临界点处混溶-不混溶（MIM）转变中的应用，包括组分之间存在线性混合（Rabi耦合，RC）和不存在线性混合的情况。 为此，我们首先通过变分近似和数值解确定了在没有管理的情况下系统所支持的多种静态域墙（DW）结构。 发现DW的近似解析解与数值解高度一致。 还给出了在受限系统中由于囚禁势的压力导致MIM转变上移的解析估计。 对于包含Pöschl-Teller势的系统，得到了精确的DW解，当势是排斥的（吸引的）时，该解是稳定的（不稳定的）。 此外，我们研究了空间均匀混合态中的线性激发谱，从而确定了系统对分离稳定/不稳定的参数区域。 特别是，RC会提高MIM转变开始的组分间排斥强度临界值。 通过监测扰动状态的演化，从数值模拟中识别了DW态上的激发特征频率。 在DW特征频率处施加弱NM揭示了非线性共振的特征。 更强的NM使系统周期性地穿过MIM转变点，从而限制了混溶性。 显示英文摘要

摘要： We investigate application of the nonlinearity management (NM, i.e., periodic variation of the strength of the inter-component repulsion) to the miscibility-immiscibility (MIM) transition across the critical point of a two-component BEC, both with and without the linear mixing (Rabi coupling, RC) between the components. To this end, we first identify, by means of a variational approximation and numerical solution, diverse stationary domain-wall (DW) structures supported by the system in the absence of the management. The approximate analytical solutions for the DWs are found to be in excellent agreement with their numerical counterparts. An analytical estimate is also produced for the upshift of the MIM transition caused by the pressure of the trapping potential in the case of a confined system. An exact DW solution is produced for the system including the P\"{o}schl-Teller potential, which is stable (unstable) if the potential is repulsive (attractive). Further, we find the spectrum of linear excitations in the spatially uniform mixed state, and thus establish parameter regions where the system is stable/unstable against demixing. In particular, RC upshifts the critical strength of the inter-component repulsion for the onset of the MIM transition. Eigenfrequencies of excitations on top of DW states are identified from numerical simulations through monitoring the evolution of perturbed states. Weak NM applied at the DW eigenfrequency reveals features of the nonlinear resonance. Stronger NM, under which the system periodically crosses the MIM-transition point, restricts the miscibility.