大N近似下玻色-爱因斯坦凝聚体中单个涡旋态的解

给出了大N近似下轴对称、扁椭球状玻色-爱因斯坦凝聚体在轴对 称各向异性谐振子势阱中单个涡旋态的一个近似解析波函数，并利用能量泛函变分的方法确 定了待定参数C与凝聚体总粒子数N和凝聚体形状因子λ的关系.C随N(或λ)的变化非常缓慢，在N和λ很大时，C趋于稳定值0.321646. 关键词： 玻色-爱因斯坦凝聚 GP泛函 涡旋态     

2维SU(NC)格点规范理论中夸克真空凝聚

用改进的Wilson夸克格点哈密顿量和变分法研究2维SU(N_C)规范场中夸克真空凝聚〈ψψ〉与夸克质量m_q和Wilson参数r的依赖关系. 结果表明: 对于给定的r, 当N_C=2,3,4,5,6,7,时, 〈ψψ〉_suba/(gN_C^3/2)的值随m_q的增大而减小. 对于较大的N_C(如N_C>3), 当m_q很小时, 〈ψψ〉_suba(gN_C^3/2)对r的依赖性很小, 但随着m_q的增大, 〈ψψ〉_suba/(gN_C^3/2)对r的依赖性增大, 且〈ψψ〉_suba/(gN_C^3/2)的值随r的增大而增大; 特别是, 当m_q→0时, 本文的格点结果与Zhitnitsky的连续理论分析结果(在弱耦合相中)很好地一致, 这意味着本文在m_q≠0时所得到的结果是可靠的.     

Transport behaviour of a Bose Einstein condensate in a bichromatic optical lattice

We investigate the Bloch and dipole oscillations of a Bose Einstein condensate (BEC) in an optical superlattice. We show that, as the effective mass increases in an optical superlattice, the BEC is localized in accordance with recent experimental observations [J.E. Lye et. al. Phys. Rev. A 75, 061603 (2007)]. In addition, we find that the secondary optical lattice is a useful additional tool to manipulate the dynamics of the atoms.      

对称双势阱玻色-爱因斯坦凝聚系统在周期驱动下的动力学相变及其量子纠缠熵表示

研究了在对称双势阱玻色-爱因斯坦凝聚体系粒子间相互作用项上外加周期调制而引起的系统动力学相变，特别地研究了该系统通向混沌的相变过程.发现在一定驱动参数下，当外加调制频率与系统固有频率达到共振时，相平面会出现不稳定性现象，即混沌.在混沌区域，粒子在各量子态随机分布，平均布居数差在零附近波动.特别地，研究表明，混沌现象的出现可以用量子纠缠熵来表征，混沌现象出现时，两种平均纠缠熵都趋于它们的最大值.     

扫描磁场中玻色-爱因斯坦凝聚体系的奇异自旋隧穿

用平均场的方法，研究了线性扫描磁场中自旋-1玻色-爱因斯坦凝聚体系的自旋隧穿.集中考虑⁸⁷Rb这种典型的碱金属原子凝聚体，根据外磁场扫描率的不同，研究了它的隧穿动力学.在慢扫描(即绝热条件)和快扫描条件下，体系无隧穿现象.对中等大小的扫描率，发现隧穿现象，且这个隧穿动力学对磁场扫描率非常的敏感，表现为看似混沌的隧穿区的存在.然而，把这个看似混沌的区域放大，发现在扫描率精度为10^-8T/s的量级上，隧穿率对磁场扫描率的关系实际是有规律的类周期结构.此外，还发现，实     

Controlling the amplitude of soliton in agrowing Bose--Einstein condensate by means of Feshbach resonance

By using Darboux transformation, this paper studies analytically the nonlinear dynamics of a one-dimensional growing Bose-Einstein condensate （BEC）. It is shown that the growing model has an important effect on the amplitude of the soliton in the condensates. In the absence of the growing model, there exhibits the stable alternate bright solitons in the condensates. In the presence of the growing model, the obtained results show that the amplitude of the bright soliton decreases （increases） for the BEC growing coefficient Ω 〈 0 （Ω 〉 0）. Furthermore, we propose experimental protocols to manipulate the amplitude of the bright soliton by varying the scattering length via the Feshbach resonance in the future experiment.     

Analogue model for an expanding universe

Over the last few years numerous papers concerning analogue models of (and for) gravity have been published. It has been shown that the dynamical equations for several condensed matter systems, (e.g., simple fluids, superfluids, Bose–Einstein condensates with a sink or a vortex) permit perturbations that are governed by the same type of wave equation as light in a curved spacetime—the curved-space d'Alembertian equation. More recently, several papers have been released which use analogue models to simulate the expanding universe. In this article the de Sitter universe will be simulated using a freely expanding three-dimensional Bose–Einstein condensate with spherical symmetry. Initially the condensate is in a harmonic trap, which is then suddenly switched off. At the same time a small perturbation is injected in the center of the condensate cloud. The motion of this perturbation in the expanding condensate will be discussed, and (after some transformations) the similarity of this system to an expanding universe will be exhibited. Finally, we briefly discuss questions of experimental observability of these effects. Presented at the 4th Australasian conference on General Relativity and Cosmology, Monash University, Melbourne, 7–9 January 2004     

Determination of carboxylic acids and phenols in water by extractive alkylation using pentafluorobenzylation,glass capillary GC and electron capture detection

A method is presented for the simultaneous determination of a wide range of carboxylic acids and phenols in water. Extractive alkylation is used with the tetrabutylammonium ion as counter ion and pentafluorobenzylbromide as alkylating agent. Extracts are analyzed by glass capillary gas chromatography and electron capture detection. Using one ml of water sample, the detection limit lies in the range of 1–10 μg/l. Application has been made to the analysis of steam condensate and domestic sewage effluent.     

Meson Effects on the Chiral Condensate at Finite Density

Meson corrections on the chiral condensate up to next-to-leading order in a 1/N_c expansion at finite density are investigated in the NJL model with explicit chiral symmetry breaking. Compared with mean-field results, the chiral phase transition is still of the first order while the properties near the critical density for chiral phase transition are found to change significantly.