Correlation effects and collective excitations in bosonic bilayers: Role of quantum statistics, superfluidity, and the dimerization transition
Correlation effects and collective excitations in bosonic bilayers: Role of quantum statistics, superfluidity, and the dimerization transition
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玻色子双层中的相关效应和集体激发：量子统计、超流性和二聚化转变的作用
DOI：
10.1103/physreva.94.013603
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发表时间：
2016
影响因子：
2.9
通讯作者：
A. Filinov
中科院分区：
文献类型：
--
作者：
A. Filinov
本文研究了一个两组分二维偶极玻色体系的双层结构。通过在很宽的层间距范围内进行量子Monte Carlo模拟，我们详细分析了对相关函数，静态响应函数，以及动能和相互作用能。通过减少层间距，我们观察到从弱到强结合二聚体状态的过渡。过渡是伴随着发病的短程相关性，抑制超流响应，和rotonization的激发光谱。用随机重构法和矩量法详细研究了二聚化过程中同相（对称）和异相（反对称）集体模的色散规律和动力学结构因子。反对称模谱的影响最强烈的抑制层超流性（指定的超流分数）。在纯超流体（正常流体）阶段，只有声[光（带隙）]模式被恢复。在部分超流相中，两者同时存在，并且分散体分裂成对应于正常和超流组分的两个分支。声学模式的谱权重与线性成比例。当由于二聚体态的形成而减少时，该权重转移到光学分支。总之，我们展示了如何在偶极双层的层间二聚可以唯一地确定静态和动态性能。
A two-component, two-dimensional (2D) dipolar bosonic system in the bilayer geometry is considered. By performing quantum Monte Carlo simulations in a wide range of layer spacings we analyze in detail the pair correlation functions, the static response function, and the kinetic and interaction energies. By reducing the layer spacing we observe a transition from weakly to strongly bound dimer states. The transition is accompanied by the onset of short-range correlations, suppression of the superfluid response, and rotonization of the excitation spectrum. A dispersion law and a dynamic structure factor for thein-phase(symmetric) andout-of-phase(antisymmetric) collective modes during the dimerization is studied in detail with the stochastic reconstruction method and the method of moments. The antisymmetric mode spectrum is most strongly influenced by suppression of the inlayer superfluidity (specified by the superfluid fraction). In a pure superfluid (normal fluid) phase, only an acoustic [optical (gapped)] mode is recovered. In a partially superfluid phase, both are present simultaneously, and the dispersion splits into two branches corresponding to a normal and a superfluid component. The spectral weight of the acoustic mode scales linearly with. This weight transfers to the optical branch whenis reduced due to formation of dimer states. In summary, we demonstrate how the interlayer dimerization in dipolar bilayers can be uniquely identified by static and dynamic properties.