Decoherence Induced by Spin Chain Environment

We study the decoherence process of an exact solvable model that consists of a central spin-1/2 coupling to the surrounding anisotropy spin-1/2 chain in transverse fields. The Loschrnidt echo is calculated to study the character of decoherence with different degree of anisotropy. Our results show that the degree of anisotropy γ greatly affects the decoherence process of the central spin-system when the spin chain is in weak transverse fields, but it gives weak effect in the strong transverse field. The decoherence process of the central system changed dramatically along the line of the critical points, and this may be explained as the reflection of quantum phase transitions.     

双奇核188Au的准粒子带结构研究

利用在束γ谱学实验技术, 通过¹⁷³Yb(¹⁹F,4nγ)反应 布居了¹⁸⁸Au的高自旋态, 并对其准粒子带结构进行了研究. 基于实验测量结果, 对原有的双奇核¹⁸⁸Au能级纲图做了较大的修改. 通过系统性比较, 对15⁺以上的能级结构进行了讨论.     

146Ce核的八级形变带和准γ带

通过测量²⁵²Cf自发裂变所产生的瞬发γ射线, 对¹⁴⁶Ce核的高自旋结构进行了重新研究, 结果更新了以前报道的能级纲图, 把八级形变集体带扩展到更高的自旋, 并且重新构建了可能的准γ带结构. 此外, 用反射不对称壳模型(RASM)对¹⁴⁶Ce核的八级形变带进行了计算, 低自旋处的计算结果与实验数据符合得很好.     

Single Qubit and Its Universal Logic Gate Made of a Heisenberg Spin Cluster with Five Particles

We investigate an anisotropic Heisenberg spin cluster with five particles controlled by a time-dependent magnetic field. With the algebraic dynamical method, we obtain the exact analytical solution to the time dependent Schr6dinger equation. Based on the analytical solution, it is shown that the system can be used as a universal single qubit logic gate controlled by the strength and frequency of the magnetic field, and the six special single qubit logic gates can be realized physically. We also discuss the anti-decoherence property of the qubit and its logic gates resulted from particle coupling effect and collectivity of the cluster.     

S[a,b]类中边界Nevanlinna-Pick插值(Ⅱ)

继续作者最近的研究,用所谓的Hankel向量方法建立S[a,b]函数类中带边界插值数据的Nevanlinna-Pick插值问题与[a,b]上的某种带约束条件的Hausdorff矩量问题之间解集之间明确的一一对应关系.通过N[a,b]函数类与S[a,b]函数类之间的联系,从而由BNP(N[a,b])问题的可解性准则和解的参数化描述获得BNP(S[a,b)问题的可解性准则和解的参数化表示.     

Li(AlxCo1-x)O2晶体中Co3+电子态的变化及对结构演化的影响

研究了应用于锂二次电池正极的新型高能量密度存贮材料Li(AlxCo1-x)O2 (x=01—05)的磁性.发现Al3+的掺杂可导致Co3+中d电子自旋态发生变化，即有部分d电子进入高自旋态.伴随Co3+中电子状态的改变，材料结构演化也发生了相应变化，表现为c/a比增大明显减缓，较好地解释了材料结构对Vegard定律的正偏离.这对材料的微观结构与性能设计具有重要意义. 关键词： 锂电池材料 Li（AlxCo1-x）O2 磁性 自旋态 结构演化     

141Nd激发态的在束γ谱学研究

通过130Te(16O,5nγ)141Nd反应布居了141Nd的高自旋态能级. 对反应产生的在束γ射线进行了γ射线单谱和γ-γ符合测量. 建立了激发能达7614.5keV的141Nd能级纲图,新发现了12条γ射线和15个能级. 基于实验测量的γ跃迁各向异性,建议了141Nd部分能级的自旋值. 用一个h11/2价中子空穴与142Nd核芯晕态的耦合可以定性地解释141Nd的能级结构.     

怀念核物理学家虞福春教授

回顾了虞福春教授一生的业绩，他是一位杰出的实验物理学家，1950年，他最早发现核磁共振谱线的化学位移，为核磁共振技术在化学领域的应用打开了大门，他测定了许多原子核的自旋和磁矩，为检验核壳结构模型作出了重要贡献，他又是一位优秀的教育家，培养了一大批物理人才，他的教学思想已经影响了几代学生。     

等电荷态离子与He原子碰撞中的转移电离过程研究

采用位置灵敏探测和飞行时间技术测量了等电荷态离子C^q 、N^q 、O^q 、Ne^q (q=4，5，6，7)与He原子碰撞中，转移电离截面与单电子俘获截面的比值Ro研究了相同q入射的情况下，R与入射离子核电荷数Z的依赖关系。在统计蒸发模型的基础上对实验结果进行了解释。     

Feynman propagator for an arbitrary half-integral spin

Based on the solution to Bargmann-Wigner equation for a particle with arbitrary half-integral spin, a direct derivation of the projection operator and propagator for a particle with arbitrary half-integral spin is worked out. The projection operator constructed by Behrends and Fronsdal is re-deduced and confirmed and simplified, the general commutation rules and Feynman propagator with additional non-covariant terms for a free particle with arbitrary half-inteRzal spin are derived, and explicit expressions for the propagators for spins 3/2, 5/2 and 7/2 are provided.