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231.
We study the fluctuation-activated transition process in a system of two coupled forced bistable oscillators with a mismatch σ in the force constants. As the coupling strength μ is increased, the transition pathway undergoes four stages changes from a two-step process with two candidate pathways to a mixture of a two-step pathway and a one-step pathway to a one-step process with also two candidate pathways and then to a one-step process with a single pathway.Interestingly, we find that the total transition rate depends nonmonotonically on σ in the weak coupling: a maximal rate appears in an intermediate magnitude of σ. Moreover, the rate also exhibits an unexpected maximum as a function ofμ. The results are in an excellent agreement with our numerical simulations by forward flux sampling. 相似文献
232.
In this paper, a scheme for generating various multiatom entangled graph states via resonant interactions is proposed. We investigate the generation of various four-atom graph states first in the ideal case and then in the case in which the cavity decay and atomic spontaneous emission are taken into consideration in the process of interaction. More importantly, we improve the possible distortion of the graph states coming from cavity decay and atomic spontaneous emission by performing appropriate unitary transforms on atoms. The generation of multiatom entangled graph states is very important for constructing quantum one-way computer in a fault-tolerant manner. The resonant interaction time is very short, which is important in the sense of decoherence. Our scheme is easy and feasible within the reach of current experimental technology. 相似文献
233.
基于具有两个近似简并基态(|g〉,|e〉)和一个激发态(|r〉)的三能级原子的两基态为静态量子比特,光子数态为飞行量子比特.两对非最大原子纠缠对中各有一个原子被分别囚禁在两个泄露腔中,在大失谐极限和激发态自发辐射系数γ远小于失谐量Δ的情况下,利用经典激光脉冲激发和与量子化腔场耦合作用后,通过对从腔中泄露出来的光子进行探测,可以将两对未知非最大原子纠缠态以一定的概率浓缩成最大纠缠态.充分考虑并且利用了腔的衰减,增强了实验的可行性和进行远距离的纠缠态浓缩的实现. 相似文献
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236.
The novel water-soluble poly(vinyl alcohol) with pendant rhodamine B moiety as colorimetric and fluorescene chemosensor for Hg2+ ions was prepared by grafting poly(vinyl alcohol) using rhodamine B hydrazide and hexamethylenediisocyanate as fluorescent dye and coupling agent, respectively. Because of their good water-solubility, the polymers binding rhodamine B can be used as chemosensors in aqueous media. With the addition of Hg2+ ions into the aqueous solution, visual color changes and fluorescence enhancements were detected. In addition, we also noticed that other metal ions such as Ag+, Cd2+, Co2+, Cu2+, K+, Mg2+, Ba2+, Fe2+, Ni2+, Pb2+, Cr3+, Fe3+ and Zn2+ cannot induce obvious changes to the fluorescence spectra of the polymer chemosensors. The combination of water solubility and positive fluorescence response as well as color change are hence particularly promising for the practical utility of the sensors. 相似文献
237.
多铁性材料CdCr2S4在磁相变温度附近的介电异常现象,为一定温度区间内共存的弛豫铁电性和铁磁性提供了磁电耦合的依据.基于Heisenberg模型,我们计算出了最近邻磁自旋对关联,最近邻磁自旋对关联通过磁电耦合修正阻碍极化翻转的激活能大小,使得被冻结在某一特定方向上的极化又能够在其它的可能取向上进行热翻转,改变了极化弛豫时间的分布,从而导致了介电性质在磁相变温度附近发生介电异常.同时,考虑温度、测量频率和磁场对介电性质的影响,得出的结果和实验数据很好吻合. 相似文献
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239.
Two new alkaline earth metal coordination polymers constructed from the deriva-tive of 1,2,4-triazole are presented herein,namely,{[Sr(AmTAZAc)2(H2O)]}(1) and {[Ba(AmTAZAc)2(H2O)]}(2)(AmTAZAc = 3-amino-1H-1,2,4-triazole-5-carboxylate),which have been synthesized by using the layering method and structurally characterized by elemental analysis,IR,and single-crystal X-ray diffraction.Complexes 1 and 2 are isostructural,and both crystallize in the orthorhombic system,space group Fdd2.X-ray structural analysis shows that 1 or 2 has an intriguing 3-D infinite network of(318.438.510) topology based on a 2-D sheet structure of(4,4) net.The result shows that noncovalent interactions play an important role in strengthening the whole structures of the compounds. 相似文献
240.
A novel coordination complex [Zn(bipy)2(H2O)4]·L·3H2O (1, bipy = 4,4'-bipyridine, LHNa = aniline-2,5-disulfonic acid monosodium salt) has been synthesized from LHNa by using hydrothermal method and structurally characterized. The result indicates that complex 1 belongs to the monoclinic system, space group P21/c with a = 20.392(3), b = 7.4052(12), c = 23.843(3) , β = 116.253(10)°, V = 3.2291(8) 3, Z = 4, Dc = 1.553 g·cm-3, μ = 0.962 mm-1, F(000) = 1568, and the final R = 0.0497 and wR = 0.1290. The complex 1 has a 0-D discrete structure, and generates an infinite 3-D network with the aid of O–H…O hydrogen bonds and π-π interactions. 相似文献