1 中国科学院上海光学精密机械研究所航天激光工程部，上海 201800
2 中国科学院大学材料科学与光电子技术学院，北京 100049
3 电子科技大学电子科学与工程学院，四川 成都 611731
4 中国科学院上海光学精密机械研究所量子光学重点实验室，上海 201800
射频蒸发冷却作为获取超冷原子简并量子气体的手段之一，对玻色-费米协同冷却的实现至关重要。为了在空间站上实现超冷量子简并气体，设计了一种特殊的射频天线。该天线被置于一个冷原子实验用真空腔内，与腔上集成的冷却、探测、光阱、磁阱、光晶格、Feshbach磁场等装置一同组成了通用型超冷原子物理实验系统，该实验系统满足载人航天工程在尺寸、重量、功耗、可靠性和电磁兼容性等方面的严格要求。利用有限元仿真方法对天线进行设计和评估，并在地面实验平台上对其各项性能指标进行测试和实验验证。结果表明，本设计除了能够降低90%的射频功率需求外，还能维持科学腔的超高真空水平，并具备良好的电磁兼容性，符合载人航天工程的要求。
量子光学 玻色-爱因斯坦凝聚体 射频诱导蒸发冷却 微波 Zeeman效应
山西大学 理论物理研究所，山西 太原 030006
本文用虚时演化方法和时间劈裂傅里叶谱方法研究了幂律势阱中玻色-爱因斯坦凝聚体的基态涡旋分布特征，具体讨论了不同幂律值、旋转角频率以及粒子间相互作用强度对涡旋分布的影响。当旋转角频率和粒子间相互作用强度不变时，随着幂律值的增大，玻色-爱因斯坦凝聚体的基态涡旋分布呈现如下特征：单量子化涡旋开始以三角晶格排列出现，随后凝聚体中心区域密度逐渐减小至零，出现中心洞，继而转变为巨涡旋结构。当相互作用强度一定时，随着幂律值越来越大，凝聚体中出现涡旋与形成巨涡旋的临界旋转角频率都随之越来越小。而当幂律值和旋转角频率一定时，逐渐增强粒子间相互作用强度，凝聚体中涡旋结构由巨涡旋转变成了三角晶格结构。
玻色-爱因斯坦凝聚体 涡旋结构 巨涡旋 幂律势阱 Bose-Einstein condensates vortex structure giant vortex power-law traps
Author Affiliations
Abstract
1 Chinese Academy of Sciences, Xi’an Institute of Optics and Precision Mechanics, State Key Laboratory of Transient Optics and Photonics, Xi’an, China
2 University of Chinese Academy of Sciences, Beijing, China
Bose–Einstein condensate (BEC) exhibits a variety of fascinating and unexpected macroscopic phenomena, and has attracted sustained attention in recent years—particularly in the field of solitons and associated nonlinear phenomena. Meanwhile, optical lattices have emerged as a versatile toolbox for understanding the properties and controlling the dynamics of BEC, among which the realization of bright gap solitons is an iconic result. However, the dark gap solitons are still experimentally unproven, and their properties in more than one dimension remain unknown. In light of this, we describe, numerically and theoretically, the formation and stability properties of gap-type dark localized modes in the context of ultracold atoms trapped in optical lattices. Two kinds of stable dark localized modes—gap solitons and soliton clusters—are predicted in both the one- and two-dimensional geometries. The vortical counterparts of both modes are also constructed in two dimensions. A unique feature is the existence of a nonlinear Bloch-wave background on which all above gap modes are situated. By employing linear-stability analysis and direct simulations, stability regions of the predicted modes are obtained. Our results offer the possibility of observing dark gap localized structures with cutting-edge techniques in ultracold atoms experiments and beyond, including in optics with photonic crystals and lattices.
Bose–Einstein condensates optical lattices photonic crystals and lattices self-defocusing Kerr nonlinearity dark gap solitons and soliton clusters Advanced Photonics
2019, 1(4): 046004
1 西安工程大学电子信息学院, 陕西 西安 710048
2 北京大学信息科学技术学院, 北京 100871
利用功率反馈排除晶格阱深波动导致的不稳定性后,主要研究了激光在空间或介质中传输的相位波动对晶格中超冷原子对比度的影响。通过晃动光晶格,人为引入可控相位噪声来测量其对原子对比度的影响,发现不同强度的相位噪声对实验结果的影响显著不同。但是小强度的相位噪声对超冷原子干涉对比度的影响并不明显,目前干涉对比度的测量精度并不能完全反映出激光相位对冷原子系统相干性的影响,说明这种空间构型光晶格在捕获超冷原子方面具有较高的稳健性。所提出的激光相位锁定技术可以有效减少晶格系统中的相位噪声,为未来空间构型光晶格中更精密的测量提供了基础。
激光器 光晶格 空间构型 玻色-爱因斯坦凝聚 对比度 锁相环 相位锁定
在冷原子物理中,对无序和温度效应的研究一直是一个非常重要的课题。基于金兹堡-朗道理论,我们从解析上研究了无序和有限温度对光晶格中超冷玻色系统相变的影响。我们的计算结果显示,无序强度的增加会使得系统的Mott绝缘相区域减小;热涨落的存在将进一步破坏Mott绝缘相,同时使得系统中出现了正常流体相。这里的金兹堡-朗道理论在最低阶近似下得到的相界方程与平均场结果一致,原则上很容易将计算结果推广到高阶从而给出超越平均场的结果。
玻色-爱因斯坦凝聚 光晶格 无序 量子相变 Bose-Einstein condensates optical lattice disorder effect quantum phase transition
1 中国科学院武汉物理与数学研究所波谱与原子分子物理国家重点实验室,湖北 武汉 430071
2 中国科学院武汉物理与数学研究所原子频标重点实验室,湖北 武汉 430071
3 中国科学院大学,北京 100049
玻色-爱因斯坦凝聚体在一维光晶格中的相位涨落是研究量子相变的重要参量。 在实验和理论上分别获得了凝聚体从光晶格中释放后的密度分布,通过分析比较两者干 涉峰的对比度提取凝聚体在光晶格中的相位涨落。应用这一方法,测量了不同光晶格阱深下凝聚 体的相位涨落。当光晶格阱深从最小值5.6ER变化到30.7ER时,相位涨落从0.29π上升 到0.69π。
量子光学 一维光晶格 玻色-爱因斯坦凝聚 相位涨落 quantum optics optical lattice Bose-Einstein condensates phase fluctuation
Author Affiliations
Abstract
We theoretically investigate quantum transport of a two-component quantum gas in a disordered potential and predict a unique disorder-induced splitting of a matter wavepacket. We also demonstrate that the splitting of the mobile component originates from the inter-component interaction and the disordered potential on the localized component.
020.0020 Atomic and molecular physics 020.1475 Bose-Einstein condensates Chinese Optics Letters
2012, 10(s2): S20201
Author Affiliations
Abstract
A method that uses radio frequency (RF) spectroscopy to evaluate the alignment of an optical lattice is proposed and demonstrated. A one-dimensional (1D) optical lattice is applied along the long axis of a cigar-shaped Bose-Einstein condensate (BEC) in a magnetic trap. The RF spectra of condensates with and without the optical lattice are analyzed, measured, and compared with the condition in which the lattice is misaligned with the BEC. The proposed method greatly optimizes the optical alignments of the lattices.
020.1475 Bose-Einstein condensates 020.7490 Zeeman effect 300.6370 Spectroscopy, microwave Chinese Optics Letters
2012, 10(9): 090201
Author Affiliations
Abstract
School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
A laser power feedback control system that features fast response, large-scale performance, low noise, and excellent stability is presented. Some essential points used for optimization are described. Primary optical lattice experiments are given as examples to show the performance of this system. With these performance characteristics, the power control system is useful for applications in cold atom physics and precision measurements.
激光功率 反馈控制 大范围 快速响应 光晶格 140.3425 Laser stabilization 020.1475 Bose-Einstein condensates 000.3110 Instruments, apparatus, and components common to the sciences Chinese Optics Letters
2011, 9(9): 091403
