利用自电离探测技术研究Sm原子Rydberg态光谱

采用孤立实激发与自电离探测技术相结合的方法对Sm原子偶宇称高激发态进行了系统研究.按照不同的自电离通道将所测数据进行了分类和比较,并进行了详细讨论.不仅报道了许多收敛于不同电离限的Rydberg态的能级位置和跃迁的相对强度等信息,而且还把处于同一能域内的Rydberg态和价态进行了辨识.另外,不但提供了一种有效识别不同类型的高激发态的鉴别技术,而且还对处于41800 cm^-1到43800 cm^-1能域内的Rydberg态和价态的光谱特性进行了详细分析和讨论. 关键词： 自电离探测 Rydberg态 Sm原子     

Study on the relations of sensitivity with energy properties for HMX and HMX-based PBXs by molecular dynamics simulation

Molecular dynamics simulation was applied to study the structure and energy properties of β-HMX (β-cyclotetramethylene tetranitramine) crystal and its composite PBXs (polymer-bonded explosives) with F₂₃₁₁ as a polymer binder under different temperatures and F₂₃₁₁ concentrations. The interface interaction energy of HMX and F₂₃₁₁, the interaction energy E_N–N between N atoms in N–NO₂ trigger bond in HMX molecules, and the cohesive energy density (CED) are presented and analyzed. A meaningful finding is that there exists correlation between E_N–N and the sensitivity of β-HMX and its composites, i.e. the less the E_N–N is, the larger the sensitivity is. Additionally, molecular interactions are inherently disclosed by using pair correlation function (PCF) to analyze the interfacial structure between (1 0 0)HMX crystal surface and F₂₃₁₁ molecular chain.     

非马尔可夫环境下经典场驱动Jaynes-Cummings模型中原子的熵压缩

运用非马尔可夫量子理论与熵压缩理论,研究了非马尔可夫环境下经典场驱动Jaynes-Cummings模型中原子的熵压缩,考察了非马尔可夫效应、经典场驱动、体系失谐量对原子熵压缩的影响.用非马尔可夫过程的记忆效应解释了原子熵压缩的动力学行为.结果表明:非马尔可夫效应和经典场驱动的共同作用有利于原子熵压缩的产生与维持.在非马尔可夫环境下,通过选择适当的系统参数,可以产生压缩度大、压缩持续时间长的原子熵压缩态.研究结果为利用光场-原子相互作用制备压缩度大、压缩持续时间长的最佳原子压缩态提供了可能途径.     

Noisy teleportation of qubit states via the Greenberger-Horne-Zeilinger state or the W state

The effects of distributing entanglement through the amplitude damping channel or the phase damping channel on the teleportation of a single-qubit state via the Greenberger--Horne--Zeilinger state and the W state are discussed. It is found that the average fidelity of teleportation depends on the type and rate of the damping in the channel. For the one-qubit affected case, the Greenberger--Horne--Zeilinger state is as robust as the W state, i.e., the same quantum information is preserved through teleportation. For the two-qubit affected case, the W state is more robust when the entanglement is distributed via the amplitude damping channel; if the entanglement is distributed via the phase damping channel, the W state is more robust when the noisy parameter is small while the Greenberger--Horne--Zeilinger state becomes more robust when it is large. For the three-qubit affected case, the Greenberger--Horne--Zeilinger state is more robust than the W state.     

Core-level photoemission of the Si(1 1 1)– -Ag surface using synchrotron radiation

The evolution of Si 2p core-level photoemission during a structural conversion from the Si (1 1 1)– -Ag to the Si(1 1 1)– -Ag superstructures induced by Ag adatoms adsorption at 140 K was studied using synchrotron radiation. The component from the top-layer Si-trimer atoms on the former surface was found to split into two components in the latter surface. The result is discussed in terms of a relaxation in some of the Si trimers induced by Ag adatoms sitting on the nearby Ag triangles of the -Ag substrate. The intensity ratio between the split components is a key to exclude some structure models proposed so far for the phases.     

Electromagnetically—induced transparency in a multi—V—type system in cesium atomic vapour

Electromagnetically-induced transparency is observed in a three-level multi-V-type system in cesium vapour at room temperature.The absorption property is measured and the hyperfine structures of atomic states can be datermined.The results of the experiment agree with the theoretical analysis.     

Direct measurement of the photon statistics of a triggered single photon source

We studied intensity fluctuations of a single photon source relying on the pulsed excitation of the fluorescence of a single molecule at room temperature. We directly measured the Mandel parameter Q(T) over 4 orders of magnitude of observation time scale T by recording every photocount. On time scale of a few excitation periods, sub-Poissonian statistics is clearly observed and the probablility of two-photons events is 10 times smaller than Poissonian pulses. On longer times, blinking in the fluorescence, due to the molecular triplet state, produces an excess of noise.     

微型热管传热极限的研究

热管技术已在电子设备散热领域得到广泛应用。热管的传热能力虽然很大,但不能无限加大热负荷。文中讨论了热管的主要极限如沸腾极限、毛细极限、粘性极限、声速极限、携带极限等的理论表达式,就一种实验用微槽平板热管进行了理论计算,得出了毛细极限是实验热管主要传热极限的结论。     

Atomic force microscopy investigation of growth process of organic TCNQ aggregates on SiO2 and mica substrates

<正>Deposition patterns of tetracyanoquinodimethane(TCNQ) molecules on different surfaces are investigated by atomic force microscopy.A homemade physical vapour deposition system allows the better control of molecule deposition. Taking advantage of this system,we investigate TCNQ thin film growth on both SiO_2 and mica surfaces.It is found that dense island patterns form at a high deposition rate,and a unique seahorse-like pattern forms at a low deposition rate.Growth patterns on different substrates suggest that the fractal pattern formation is dominated by molecule-molecule interaction.Finally,a phenomenal "two-branch" model is proposed to simulate the growth process of the seahorse pattern.     

Photonic true-time delay unit for broadband adaptive nulling in antenna arrays

An Opto-VLSI-based (VLSI: very-large-scale-integration) tunable true-time delay (TTD) generation unit used for adaptive null steering in phased array antennas is presented. The system is based on continuous tunable optical TTD technique. Arbitrary multiple true-time delays to generate multiple broadband nulls can simultaneously be synthesised for each antenna element. The proposed structured are characterised both theoretically and experimentally. Experimental results demonstrating the principle of the true-time delay for null generations are presented. The maximum time delay measured for a wavelength tuning from 1530 to 1560 nm is 9.5 ns.