In calculations to date [1,2] of multi-layer stacks of dipolar condensates, created in one-dimensional optical lattices, the condensates have been assumed to be two-dimensional. In a real experiment, however, the condensates do not extend to infinity in the oblate direction, but have to be confined by a trap potential, too. By three-dimensional numerical simulations of this realistic experimental situation we find a crucial dependence of the phonon instability boundary on the number of layers. Moreover, near the boundary of the phonon instability, a variety of structured ground-state wave functions emerges, which may indicate the onset of a roton instability [3,4].
Collective interlayer pairing and pair superfluidity in vertically stacked layers of dipolar excitons
人们认为分层玻色子偶极流体含有层间分子束缚态的凝聚物。然而，它的实验观察仍然难以捉摸。受最近两项实验工作的启发[Hubert等人，Phys. Rev. X 9，021026（2019）和D. J. Choksy等人，物理评论B 103 045126（2021）]，我们理论上研究，使用数值精确的量子蒙特卡罗计算，集体层间配对的实验签名在垂直堆叠的间接激子（IX）层。我们发现，IX能量转移与每一层的发展非平凡的密度不平衡的函数以下的非单调的趋势与跳跃不连续的密度平衡，确定与层间IX分子间隙。这种行为区分层间束缚对的超流性和不同层中独立的偶极凝聚。考虑到有限的温度和有限的密度不平衡的条件下，我们发现一个级联的Berezinskiii-Kosterlitz-无（BKT）的过渡，最初到一对超流，然后才在较低的温度下，到两个层的完全超流。我们的结果可以提供一个理论解释现有的实验观察在GaAs双量子阱（DQW）双层结构。此外，在未来的研究中，为了优化配对动力学的可见性，我们提出了一个分析，建议现实的实验设置在GaAs和过渡金属二硫属化物（TMD）双层DQW异质结构，集体层间配对和对超流性可以清楚地观察到。
