高Tc氧化物超导体的性参数的研究

在高Ｔｃ氧化物超导体的研究中，引入分子平均电负性ＸＭＯ、单位氧原子上阳离子加合电离势∑ＩＭ和原子部分电荷δ０及δＭ的计算方法，并对ＹＢＣＯ、ＹＢＳＣＯ、ＢＩＳＣＣＯ、ＴＬＢＣＣＯ、ＴＩＲＥＣＣＯ、ＴＩＲＥＳＣＣＯ及ＲＥＢＣＯ等系列的Ｔｃ变化规律，进行了研究。     

玻色-爱因斯坦凝聚的实现及应用

 玻色－爱因斯坦凝聚（Ｂｏｓｅ－ＥｉｎｓｅｉｎＣｏｎｄｅｎｓａｔｉｏｎ,简称ＢＥＣ）是爱因斯坦于１９２５年预言的奇特的凝聚现象．７０年过去了,人们一直在寻找可能的ＢＥＣ候选者．近２０年来,随着碱金属原子的激光冷却和囚禁技术取得的巨大进展,高密度大数目产生超冷原子气体已成为可能,在此基础上,１９９５年,３个美国研究小组相继实验实现了碱金属原子气体ＢＥＣ,震惊了整个物理学界．ＢＥＣ是物理学家长期梦寐以求观察的物理现象,它的实现带来了广阔的应用前景．本文将对产生ＢＥＣ的物理条件,实验技术和研究历史作详细介绍,并简述ＢＥＣ研究的近期发展和重要应用──原子激光器．     

BEC实验研究新进展

玻色－爱因斯坦凝聚（ＢＥＣ）的实验实现,是近年来物理学领域中十分重要的一个进展．基于ＢＥＣ的形成继而实现的原子激射器［１］（ａｔｏｍｌａｓｅｒ）更展示了十分吸引人的应用前景,其在科学技术上的意义至今尚难以完全估计．目前,ＢＥＣ研究的核心仍然是ＢＥＣ的...     

诺贝尔奖得主的新贡献

20 0 1年度的诺贝尔物理奖被授予在原子气玻色 -爱因斯坦凝聚 (ＢＥＣ)领域作出贡献的三位美国科学家 :ＥｒｉｃＡ .Ｃｏｒｎｅｌｌ,ＷｏｌｆｇａｎｇＫｅｔｔｅｒｌｅ和ＣａｒｌＥ .Ｗｉｅｍａｎ .1995年 ,他们先后在87Ｒｂ蒸气和2 3 Ｎａ蒸气系统中实现了ＢＥＣ .今天 ,全世界已有 30多个研究小组开展了这一领域的实验研究 ,发表了 2 5 0 0 0多篇科学论文 .研究者们认为 ,通过实现ＢＥＣ可以提高原子钟的精度 ,并使卫星导航系统的定位精度提高到 10ｃｍ左右 .此外 ,这项研究也与凝聚态物理的超导涡旋、密切相关 ,与宇宙中天体之间以及天体…     

诺贝尔奖得主的新贡献

20 0 1年度的诺贝尔物理奖被授予在原子气玻色 -爱因斯坦凝聚 (ＢＥＣ)领域作出贡献的三位科学家 :ＥｒｉｃＡ .Ｃｏｒｎｅｌｌ,ＷｏｌｆｇａｎｇＫｅｔｔｅｒｌｅ和ＣａｒｌＥ .Ｗｉｅ ｍａｎ .1995年 ,他们先后在87Ｒｂ蒸气和2 3 Ｎａ蒸气系统中实现了ＢＥＣ .今天 ,全世界已有 30多个研究小组开展了这一领域的实验研究 ,发表了 2 5 0 0 0多篇科学论文 .研究者们认为 ,通过实现ＢＥＣ可以提高原子钟的精度 ,并使卫星导航系统的定位精度提高到10ｃｍ左右 .此外 ,这项研究也与凝聚态物理的超导涡旋、超流涡旋密切相关 ,与宇宙中天体之间以及…     

YBCO/CeO_2/LaAlO_3夹层膜的界面研究

用俄歇电子能谱（ＡＥＳ）结合透射电子显微镜（ＴＥＭ）对磁控溅射法制备的ＹＢＣＯ／ＣｅＯ２／ＬａＡｌＯ３夹层膜中的元素在各层间的扩散行为进行了研究．结果表明，ＣｅＯ２作为一种缓冲层，能够阻挡住基底ＬａＡｌＯ３中元素向ＹＢＣＯ膜的扩散和ＹＢＣＯ膜中元素向基底的扩散，其本身向ＹＢＣＯ膜中的扩散也不多．ＴＥＭ的分析表明，ＣｅＯ２能保持完好的晶格结构，在其上能得到结构完整的高质量ＹＢＣＯ膜     

THE MACQM CALCULATION OF THE TOTAL ENERGY CURVE OF THE BODY-CENTERED CUBIC STRUCTURE OF THE H_9~- CLUSTER

ＴＨＥＭＡＣＱＭＣＡＬＣＵＬＡＴＩＯＮＯＦＴＨＥＴＯＴＡＬＥＮＥＲＧＹＣＵＲＶＥＯＦＴＨＥＢＯＤＹ－ＣＥＮＴＥＲＥＤＣＵＢＩＣＳＴＲＵＣＴＵＲＥＯＦＴＨＥＨ－９ＣＬＵＳＴＥＲＧｏｕＱｉｎｇｑｕａｎＺｈａｎｇＪｉａｎｐｉｎｇＬｉＰｉｎｇＩｎｓｔｉｔｕ...     

CsMgX3：V^2＋（X=Cl,Br）中配体SO耦合对EPR参量的贡献

用双自旋－轨道耦合系数模型研究了晶体ＣｓＭｇＣｌ３和ＣｓＭｇＢｒ３中掺杂Ｖ２＋离子的ＥＰＲｇ因子和零场分裂Ｄ。计算中，用半经验方法确定了分子轨道系数。研究表明，对Ｂｒ－这类有强共价性和大ＳＯ耦合系数的配体，其ＳＯ耦合作用对络合物ＥＰＲ参量的贡献不可忽略。     

玻色-爱因斯坦凝聚的物理实现及其应用展望

综述了形成玻色－爱因斯坦凝聚的物理条件及其近年来的研究进展情况．叙述了实现ＢＥＣ的几种关键实验技术，并展望了ＢＥＣ的应用前景     

掺稀土离子的CaS：Bi荧光粉的发光性质

采用固相反应法合成了单掺和双掺稀土离子Ｔｍ３＋、Ｅｒ３＋的ＣａＳ：Ｂｉ荧光粉，测定了试样的荧光光谱和有效余辉。与ＣａＳ：Ｂｉ相比，掺入Ｔｍ３＋、Ｅｒ３＋的荧光粉，Ｂｉ３＋特征发射峰４４７ｎｍ增强，有效余辉延长。表明Ｔｍ３＋、Ｅｒ３＋对Ｂｉ３＋在ＣａＳ中的发光产生了敏化作用，Ｔｍ３＋、Ｅｒ３＋在基质晶格中造成了缺隙深能级，讨论了Ｔｍ３＋、Ｅｒ３＋对ＣａＳ：Ｂｉ发光敏化作用的大小和在基质中造成缺隙能级。的深浅。     

Quantum dynamics of an impurity-doped Bose-Einstein condensate system

We study the quantum dynamics of an impurity-doped Bose–Einstein condensate (BEC) system. We show how to generate the macroscopic quantum superposition states (MQSSs) of the BEC by the use of projective measurements on impurity atoms. It is found that the nonclassicality of MQSSs can be manipulated by changing the number of the impurities and their interaction with the BEC. It is shown that the BEC matter-wave field exhibits a collapse and revival phenomenon which reveals the quantum nature of the BEC matter-wave field. We investigate the micro-macro entanglement between the impurities and the BEC, and find enhancement of the micro-macro entanglement induced by the initial quantum coherence of the impurity atoms.     

The <Superscript>55</Superscript>Mn Spin Echo Test of Magnon BEC State in MnCO<Subscript>3</Subscript>

The coherent quantum state of magnons—Bose–Einstein condensate (BEC) has been observed in several types of antiferromagnets. According to the Bose statistics of magnons, BEC appears when the magnon density exceeds the critical density N _BEC and the magnon gas condenses to a quantum liquid. The BEC state is characterized by a coherent precession of the magnetization. In this paper, the first experiments showing the suppression of the spin echo signal by the magnon BEC is presented. These experiments confirm the coherence of magnetic excitations in the BEC state.     

外势场作用下的玻色-爱因斯坦凝聚啁啾孤子的演化与操控

提出了一种处理玻色-爱因斯坦凝聚啁啾孤子动力学的拓展变分方法,深入研究了玻色-爱因斯坦凝聚孤子在周期势与抛物势联合作用下的动力学演化,利用拓展变分法给出了解析处理,并和基于分步傅里叶变换的直接数值法进行比较,发现这种拓展变分方法能够充分揭示上述外势场中的玻色-爱因斯坦凝聚啁啾孤子的动力学行为和特征．同时给出了能支持多稳定晶格囚禁玻色-爱因斯坦凝聚啁啾孤子的周期势与抛物势强度比值的临界值和一种通过控制外势场可有选择地移动玻色-爱因斯坦凝聚啁啾孤子的操控方法,这为玻色-爱因斯坦凝聚的实验和应用研究提供了理论参 关键词： 玻色-爱因斯坦凝聚 Gross-Pitaevskii方程 啁啾孤子 操控     

玻色-爱因斯坦凝聚态的临界温度移动

从平均场理论出发,针对有限温度下的玻色-爱因斯坦凝聚态的特点,从正则系综的自由能函数变化的角度,推演并得出了临界温度移动的表达式。为同类实验提供了理论依据.     

An energy sum constraint of event mixing for Bose-Einstein correlations in reactions with ππX final states around 1 GeV

We present a new event mixing technique for measuring two-pion Bose-Einstein correlations(BEC)in reactions with only two identical bosons among three final state particles.This new mixing method contains a missing mass consistency(MMC)cut and an energy sum order(ESO)cut.Unlike the previous proposed pion energy cut,which abandons nearly half the original events,the ESO cut does not eliminate any original events and hence improves the statistics of both original events and mixed events.Numerical tests using theγp→π~0π~0p events around1 Ge V are carried out to verify the validity of the ESO cut.This cut is able to reproduce the relative momentum distribution of the original events in the absence of BEC effects.In addition,its ability to observe BEC effects is tested by an event sample in the presence of BEC effects.Simulation results show the BEC effects can be observed clearly as an enhancement in the correlation function,and the BEC parameters extracted by this event mixing cut are consistent with the input BEC parameters.     

Nonadiabatic effects on population transfer of two Bose－Einstein condensates induced by atomic interaction

We investigate the stimulated Raman adiabatic passage for Bose－Einstein condensate (BEC) states which are trapped in different potential wells or two ground states of BEC in the same trap. We consider that lasers are nearly resonant with the atomic transitions. The difference of population transfer processes between BEC atoms and usual atoms is that the atomic interaction of the BEC atoms can cause some nonadiabatic effects, which may degrade the process. But with suitable detunings of laser pulses, the effects can be remedied to some extent according to different atomic interactions.     

Band structures of a slowly rotating dipolar Bose-Einstein condensate with a quantized vortex along a one-dimensional optical lattice

We derive the effective Gross-Pitaevskii equation for a slowly rotating dipolar Bose-Einstein condensate (BEC) with a quantized vortex along a one-dimensional optical lattice and calculate its band structures. The band structure of a slowly rotating BEC in a lattice becomes interesting when dipole-dipole interaction (DDI) is involved. Under rotation, a dipolar rotating term emerges from the DDI potential. The dipolar rotating term makes a BEC with an attractive DDI more stable than one with a repulsive DDI. The dipolar rotating term changes and generalizes the definition for the type of BEC, which cannot be simply determined by an s-wave scattering length or an effective contact interaction term. The dipolar rotating term also makes the band structure fascinating and tunable. A so-called swallowtail band structure, i.e., a multi-valued solution due to nonlinear interaction, can either elongate or shrink as the band index increases, in contrast to a non-rotating dipolar BEC system with a monotonic dependence. With the dipolar rotating term, various band structures as well as an attractive BEC without collapse can be easily achieved. We demonstrate that a rotating dipolar BEC system subject to an optical lattice combines features of a crystal and a superfluid and promises wide applications.     

Localization of two-component Bose-Einstein condensates in optical lattices

We study nonlinear localization of a two-component Bose-Einstein condensate (BEC) in a one-dimensional optical lattice. Our theory shows that spin-dependent optical lattices can be used to effectively manipulate the nonlinear interactions between the BEC components, and to observe composite localized states of a BEC in both bands and gaps of the matter-wave spectrum.     

Stability of Bose-Einstein condensates of hot magnons in yttrium iron garnet films

We investigate the stability of the recently discovered room-temperature Bose-Einstein condensate (BEC) of magnons in yttrium iron garnet films. We show that magnon-magnon interactions depend strongly on the external field orientation, and that the BEC in current experiments is actually metastable-it only survives because of finite-size effects, and because the BEC density is very low. On the other hand a strong field applied perpendicular to the sample plane leads to a repulsive magnon-magnon interaction; we predict that a high-density room-temperature magnon BEC should then form in this perpendicular field geometry.     

相互作用原子玻色-爱因斯坦凝聚体诱导的光场压缩效应

给出了光场与二能级原子玻色-爱因斯坦凝聚体(BEC)相互作用系统的哈密顿量，研究了原子 间相互作用对压缩相干态光场与原子BEC相互作用系统中光场正交压缩特性的影响.结果表明 ：光场两正交分量的涨落均随时间按余弦规律周期性地变化，其压缩性质依赖于光场的初始 压缩因子和压缩方向角，而原子间的相互作用影响光场正交分量的涨落随时间变化的幅度和 周期. 关键词： 玻色-爱因斯坦凝聚 压缩相干态 光场的正交压缩