维生素A衍生物合成工艺的改进

维生素A衍生物合成工艺的改进;多双键烷基膦衍生物;Wittig-Horner反应     

Nonresonant and stochastic heating of ions by low-frequency wave

The present paper addresses the nonresonant and stochastic heating of minor ions by a low-frequency Alfvén wave in the solar wind. A new and whole physical mechanism that enables the heating of ions by a low-frequency parallel propagating wave with finite amplitude in a low beta plasma. The heating process has two stages: First, ions are picked up via low-frequency wave–ion nonresonant interaction and the ion energy gain depends on the ratio of the wave electric-field energy to background magnetic-field energy. Second, when the velocity approaches the threshold value, the stochastic heating is prominent. The stochastic heating of ions sustains until the average parallel speed is close to the wave velocity.     

Spin pumping at the Co2FeAl0.5Si0.5/Pt interface

Spin pumping at the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces has been studied by ferromagnetic resonance technology(FMR). The spin mixing conductance of the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces was determined to be 3.7×1019m 2and 2.1×1019m 2 by comparing the Gilbert damping in a Co2FeAl0.5Si0.5single film, Co2FeAl0.5Si0.5/Pt bilayer film and a Pt/Co2FeAl0.5Si0.5/Pt trilayer film. Spin pumping is more efficient in the Co2FeAl0.5Si0.5/Pt bilayer film than in permalloy/Pt bilayer film.     

等离子体增强化学气相沉积法制备含氢类金刚石膜的紫外Raman光谱和X射线光电子能谱研究

利用脉冲辉光放电的方法,在硅片上采用不同的沉积工艺制备了含氢类金刚石膜层,并采用Raman光谱和X射线光电子能谱(XPS)对膜层进行表征.用Raman光谱仪在波长为325 nm的紫外光源的激励下观察膜层的键结构.紫外Raman光谱对含氢类金刚石膜是非常有用的,它能有效避免可见光Raman光谱测量时的荧光干扰,清晰地得到膜层的D峰和G峰.同时利用XPS分析得到膜层的sp3键含量,并与Raman光谱所得数据进行比较.通过Raman光谱和XPS分析可以发现,在紫外光源的激励下,膜层的G峰峰位向高频移方向移动,G峰峰位、I(D)/I(G),G峰半高宽和sp3键含量之间存在一定的关系.     

Entanglement Swapping for Cluster-Class States and Its Applications in Quantum Information Processing

Entanglement swapping for four-qubit cluster-class states is studied. It is shown that a four-qubit cluster state (maximally entangled) can be obtained with a certain probability from two four-qubit cluster-class states by entanglement swapping. The probability is related to the smallest superposition coefficient of the cluster-class states (when all the moduli of amplitudes are equivalent, they are the usual cluster states and the probability hits to one). Two examples for the applications of the entanglement swapping are also presented. One is quantum teleportation of an arbitrary two-qubit state via a quantum repeater, in which the success probability can be improved by the entanglement swapping when the quantum channels are general cluster-class states (partially entangled). The other is quantum key distribution, in which a secret random sequence of bits (a “key”) can be efficiently established between two distant parties by the entanglement swapping of two groups of cluster states.     

Mechanical Properties and Electronic Structure of N and Ta Doped TiC: A First-Principles Study

The first principles calculations based on density functional theory (DFT) are employed to investigate the mechanical properties and electronic structure of N and Ta doped TiC. The result shows that the co-doping of nitrogen and tantalum dilates the lattice constant and improves the stability of TiC. Nitrogen and tantalum can significantly enhance the elastic constants and elastic moduli of TiC. The results of B/G and C₁₂-C₄₄ indicate tantalum can markedly increase the ductility of TiC. The electronic structure is calculated to describe the bonding characteristic, which revealed the strong hybridization between C-p and Ta-d and between N-p and Ti-d. The hardnessis is estimated by a semi-empirical model that is based on the Mulliken overlap population and bond length. While the weakest bond takes determinative role of the hardness of materials, the addition of Ta sharply reduces the hardness of TiC.     

Feasible schemes for quantum swap gates of optical qubits via cavity QED

Feasible schemes for implementing quantum swap gates of both coherent-state qubits and photonic qubits are proposed using a Λ-type atomic ensemble trapped in a bimodal optical cavity. In both protocols, the decoherence from atomic spontaneous emission is negligible due to the fact that the excited states of the atoms are adiabatically eliminated under large detuning condition and the swap gates can be created in a single step. In our schemes, the required atoms-cavity interaction time decreases with the increase of the number of atoms, which is very important in view of decoherence. The experimental feasibilities of the schemes are also discussed.     

Realization of Three-Qubit Controlled-Phase Gate Operation with Atoms in Cavity QED System

We propose a scheme for realization of three-qubit controlled-phase gate via passing two three-level atoms through a high-Q optical cavity in a cavity QED system. In the presented protocol, the two stable ground states of the atoms act as the two controlling qubits and the zero- and one-photon Fock states of the cavity-field form the target qubit, and no auxiliary state or any measurement is required. The numerical simulation shows that the gate fidelities remain at a high level under the influence of the atomic spontaneous emission, the decay of the cavity mode and deviation of the coupling strength. The experimental feasibility of our proposal is also discussed.     

帽状铜纳米粒子的制备及表面增强拉曼散射活性研究

采用真空热蒸发法在SiO₂纳米粒子自组装单层膜上沉积铜薄膜制备了帽状铜纳米粒子。用扫描电镜、原子力显微镜和紫外-可见-近红外分光光度计对帽状复合纳米粒子的表面形貌和光学性质进行了表征。以亚甲基蓝和吡啶-(2-偶氮-4)间苯二酚为探针分子,研究了该复合纳米粒子的表面增强拉曼散射(SERS)活性。通过比较吸附在不同基底上的吡啶-(2-偶氮-4)间苯二酚的谱峰强度,探讨了SERS效应与表面等离子体共振(SPR)的关系。     

碱石灰玻璃表面长方形银纳米颗粒的制备与表征

采用离子交换结合热处理的方法在碱石灰玻璃表面制备了银纳米颗粒。通过紫外-可见分光光度计、X射线衍射仪、扫描电子显微镜对样品进行了表征。结果表明:热处理时,银离子在玻璃表面成核并生长成近似长方形的纳米颗粒。吸收光谱在416nm附近出现明显的银纳米颗粒表面等离子体共振吸收特征峰。