Dynamics of remote entanglement in one-dimensional Ising chains with Dzyaloshinskii-Moriya interactions

With the introduction of Dzyaloshinskii-Moriya (DM) interaction, dynamics of the remote entanglement in one-dimensional Ising chains is investigated. It is found that the DM interaction can excite the remote entanglement from an initial Néel state. For a given strength of DM interaction, the concurrence between the end spins oscillates and decreases simultaneously with the increase of the chain’s length, and drops to zero at a critical length. For the chains with two and three spins, it is very interesting that the dynamics of the staggered magnetization (or the chiral parameter) can be used to qualitatively estimate the evolution of the remote concurrence between the end spins. At last, we discuss the generation of W state from the Ising chain with DM interactions, and it is obtained that W state can only be prepared in the three-qubit and four-qubit chains with a specific strength of DM interaction.     

Gradient Estimates for the Heat Kernels in Higher Dimensional Heisenberg Groups

The author obtains sharp gradient estimates for the heat kernels in two kinds of higher dimensional Heisenberg groups -- the non-isotropic Heisenberg group and the Heisenberg type group Hn,m. The method used here relies on the positive property of the Bakry-Emery curvature F2 on the radial functions and some associated semigroup technics.     

Study of Dynamics in Spin-1/2 Chain Using Adaptive Time-Dependent Density-Matrix Renormalization-Group Method

A numerical method of the adaptive time-dependent density-matrix renormalization-group (t-DMRG) is introduced to calculated one-dimensional quantum spin systems with next-nearest-neighbor interaction. The algorithm to study the local magnetization in spin-1/2 Heisenberg XX chain is checked. The analysis of error indicates that this method is efficient to study the spin-1/2 chain with next-nearest-neighbor interaction. By using of the method, the effects of the next-nearest-neighbor interaction on the dynamics of the local magnetization and entanglement entropy are studied.     

含有5-甲基-3-吡唑甲酸的铅(Ⅱ)配合物:合成、结构和荧光性质

在不同含N辅助配体的存在下,将5-甲基-3-吡唑甲酸(H_2MPCA)与相应的铅(Ⅱ)盐反应制得了2个新的配合物:[Pb(HMPCA)_2(H_2O)_2]·H_2O (1)和[Pb(HMPCA)_2(phen)]·H_2O (2)(phen=菲咯啉)。双核配合物1中双核[Pb(μ_2-HMPCA)]_2单元在一对Pb…O次级键的作用下形成了一维链状结构,这些一维链在氢键的作用下进一步自组装成2D超分子结构。而单核化合物2在Pb…O次级键的作用下形成了Pb_2O_2平面,它们在π…π和氢键作用下堆积形成3D超分子结构。考察了配合物1和2的热稳定性、荧光性能。     

MWCNTs复合物纳米流体的摩擦学性能

将油性剂油酸(OA)填充进多壁碳纳米管(MWCNTs)的空腔内制备复合物，再以复合物为添加剂制备一种纳米流体，考察了复合物的质量分数、MWCNTs的酸处理时间以及摩擦测试条件等对纳米流体摩擦学性能的影响，并分析了复合物的润滑机理. 结果表明:油酸被成功填充到经酸处理的MWCNTs管内，填充率约20%；摩擦过程中，复合物制备的纳米流体的摩擦系数有不断减小趋势，其减摩效果甚至优于同等含量的油酸乳化液；当复合物的质量分数为0.1%左右时，纳米流体可获得最佳的减摩、抗磨效果；随着酸化处理时间的增加，复合物制备的纳米流体的减摩、抗磨性能会有所提高. 摩擦过程中，复合物可释放出油酸并形成润滑膜，MWCNTs则能够在油酸形成的润滑膜上发挥“微轴承”的作用，从而使复合物获得更加优良的减摩、抗磨效果.      

超声动载荷下三维随机骨料混凝土的损伤

混凝土是一种由粗骨料与水泥砂浆组成的非均质复合材料。本研究利用APDL语言程序编写三维水泥混凝土骨料随机投放程序并导入ABAQUS中,同时赋予各相材料塑性损伤本构关系来研究混凝土动态加载下的破坏规律,运用超声波在混凝土破碎中的作用机理对混凝土动态损伤破坏过程进行模拟研究。结果表明:随着超声动态载荷的增大,粗骨料体积分数为40%的混凝土始终能够承受最大应力载荷;随着超声应力波幅值增大,混凝土在动载荷下的损伤值逐渐增大,且粗骨料体积分数为40%时,其抗损伤能力最优;当粗骨料最大粒径逐渐增大,或者当粗骨料最小粒径增大,混凝土级配不合理导致性能不稳定,更易损伤破坏。     

Heterobimetallic Cluster-Based Coordination Polymers: Assembly,Structures and Third-Order Nonlinear Optical Properties

Reactions of (NH₄)₂WS₄ with CuCN, CuCN/1,2-bis(4-pyridyl)propane (bppa) or [Cu(MeCN)₄]PF₆/bppa under different reaction conditions afforded a set of two- or three-dimensional W/Cu/S cluster-based coordination polymers including {[Et₄N]₂[WS₄Cu₄(μ-CN)₂(μ-I)₂]}_n ( 1 ), [WS₄Cu₄(μ-CN)₂(bppa)₂]_n ( 2 ) and {[WS₄Cu₄(bppa)₄](PF₆)₂}_n ( 3 ), respectively. Compound 2 can be readily formed from reaction of 1 with bppa under solvothermal conditions. Compounds 1 and 2 feature two-dimensional networks with a “sql” topology, while 3 possesses a two-fold interpenetrated three-dimensional net with a rare “reo” topology. Compounds 1 – 3 in DMF exhibited different third-order nonlinear optical responses, and they all showed a reverse saturable absorption while 2 held a strong self-focusing effect.     

Normality and attracting fixed points

Let k 2 be a fixed integer. We construct a non-normal familyof meromorphic functions in the unit disc with kth iteratesthat have no non-attracting fixed points in the unit disc. Wealso prove that a family of meromorphic functions in a planedomain is normal if all fixed points in the domain of the k-iteratesof all functions in the family are uniformly attracting.