发表机构
South China Normal University（华南师范大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一维PT对称双色光学晶格，研究弱排斥玻色-爱因斯坦凝聚体中耗散与相互作用对莫尔平带的影响，发现其响应具有宇称相关性，为相关实验研究奠定基础。
AI 中文摘要
一维超晶格提供了一个从低维视角探索莫尔物理的简化平台，其晶格常数的比值与二维双层结构中的扭转角发挥类似作用。本文针对弱排斥玻色-爱因斯坦凝聚体提出一种一维PT对称双色光学晶格，研究耗散与相互作用的相互影响对最低莫尔平带的作用。无相互作用时，我们发现由公度比诱导的最低带平带对PT对称虚势呈现与宇称相关的响应，这源于能谱的PT配对机制不同：分母为偶数的比值（即偶宇称）中，能级吸引及PT对称破缺发生在最低两个带内，导致最低平带单调展宽；而分母为奇数的比值（即奇宇称）中，PT对称破缺发生在第二和第三低带内，最低带保持纯实数，因此呈现非单调响应，该宇称相关现象可通过微扰理论解释。此外，通过求解Gross-Pitaevskii方程，我们还发现：尽管弱排斥相互作用本身可展宽莫尔带，但相互作用与虚势的共同作用也会产生宇称相关行为；偶宇称下带平坦度持续降低，而奇宇称下虚势可增强或减弱平坦度。这些结果为莫尔系统中耗散和相互作用对带平坦度影响的实验研究铺平了道路。
英文摘要
One-dimensional (1D) superlattices provide one simplified platform for exploring moiré physics from a low-dimensional perspective, with the ratio of lattice constants playing a role analogous to the twist angle in two-dimensional bilayers. Here, we propose a 1D $\mathcal{PT}$-symmetric bichromatic optical lattice for a weakly repulsive Bose-Einstein condensate and investigate how the interplay of dissipation and interaction impacts the lowest moiré flat band. Without interaction, we find that the lowest-band flatness induced by commensurate ratios exhibits a parity-dependent response to the $\mathcal{PT}$-symmetric imaginary potential due to the distinct $\mathcal{PT}$ pairing mechanism for the energy spectrum. For ratios with even denominators (i.e., even parities), the level attraction and thus the $\mathcal{PT}$-symmetry breaking occur within the lowest two bands, leading to a monotonic broadening of the lowest flat band, whereas odd denominators (i.e., odd parities) yield a nonmonotonic response due to the $\mathcal{PT}$-symmetry breaking within the second and the third lowest bands instead while the lowest band remains purely real. This parity-dependent phenomenon can be understood by the perturbation theory. Furthermore, by solving the Gross-Pitaevskii equation, we also find that although the weak repulsive interaction can broaden the moiré bands alone, the combined effects of interaction and imaginary potential also lead to parity-dependent behaviors. For even parities, band flattening is consistently diminished, whereas for odd parities, the imaginary potential can either enhance or reduce the degree of flattening. These results pave the way for experimental studies of dissipation and interaction effects on band flatness in moiré systems.
Comments14 pages, 7 figures
Journal refPhys. Rev. A 114, 033310 (2026)
