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Nonlinear localized modes in one-dimensional nanoscale dark-state optical lattices
Nanophotonics ( IF 7.5 ) Pub Date : 2022-06-22 , DOI: 10.1515/nanoph-2022-0213
Zhiming Chen, Jianhua Zeng

Optical lattices (OLs) with conventional spatial periodic λ/2, formed by interfering the counterpropagating laser beams with wavelength λ, are versatile tools to study the dynamical and static properties of ultracold atoms. OLs with subwavelength spatial structure have been realized in recent quantum-gas experiment, offering new possibility for nonlinear and quantum control of ultracold atoms at the nano scale. Herein, we study theoretically and numerically the formation, property, and dynamics of matter-wave localized gap modes of Bose–Einstein condensates loaded in a one-dimensional nanoscale dark-state OL consisted of an array of optical subwavelength barriers. The nonlinear localized modes, in the forms of on- and off-site fundamental gap solitons, and dipole ones, are demonstrated; and we uncover that, counterintuitively, these modes exhibit always a cusplike (side peaks) mode even for a deeply subwavelength adiabatic lattice, contrary to the previously reported results in conventional deep OLs where the localized gap modes are highly confined in a single lattice cell. The (in)stability features of all the predicted localized modes are verified through the linear-stability analysis and direct perturbed simulations. Our predicted results are attainable in current ultracold atoms experiments with the cutting-edge technique, pushing the nonlinear control of ultracold atoms with short-period OLs as an enabling technology into subwavelength structures.

中文翻译:

一维纳米级暗态光学晶格中的非线性局部模式

具有传统空间周期的光学晶格 (OL)λ/2,由对向传播的激光束与波长干涉形成λ,是研究超冷原子的动态和静态特性的通用工具。在最近的量子气体实验中实现了具有亚波长空间结构的OLs,为纳米尺度超冷原子的非线性和量子控制提供了新的可能性。在这里,我们从理论上和数值上研究了加载在一维纳米级暗态 OL 中的 Bose-Einstein 凝聚体的物质波局部间隙模式的形成、性质和动力学,该 OL 由一组光学亚波长屏障组成。展示了以场内和场外基本间隙孤子和偶极子形式存在的非线性局部模式;我们发现,与直觉相反,即使对于深亚波长绝热晶格,这些模式也总是表现出尖峰(侧峰)模式,与先前报道的传统深 OL 的结果相反,其中局部间隙模式高度限制在单个晶格单元中。通过线性稳定性分析和直接扰动模拟验证了所有预测的局部模式的(不)稳定性特征。我们的预测结果可以在当前采用尖端技术的超冷原子实验中实现,将具有短周期 OL 的超冷原子的非线性控制作为一种使能技术推向亚波长结构。
更新日期:2022-06-22
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