Element base of quantum informatics II: Quantum communications with single photons

Quantum cryptography can provide almost complete security of the data transmitted in optical telecommunication systems by single photons based on the laws of quantum mechanics. The paper presents a brief overview of the element base and experimental investigations in the field of quantum cryptography and data transmission by single photons in atmospheric and optical fiber quantum communication lines. Two experimental setups for the single-photon quantum key distribution in the atmospheric and optical fiber quantum channels are described. The results of the quantum key distribution experiments performed on them are given.     

Cold atoms in optical lattices as qubits for a quantum computer

An overview is presented of qubit arrays in the form of cold neutral atoms trapped in an optical lattice. The current status and future direction of this qubit realization are discussed. A variant is considered that is based on the dipole-dipole interaction of atoms excited into Rydberg states. The results are presented of the first experiments on the observation of the dipole-dipole interaction between a small number of Rydberg atoms.     

Nanoelectromechanical diamond structures in quantum informatics. Part I

Techniques for fabricating nanomechanical diamond systems and their use in modern micro- and nanoelectronics are reviewed. The primary focus is the experimental techniques for controlling the quantum state of nitrogen-vacancy centers in diamond by mechanical actions. Optimization of the working characteristics of diamond resonators is discussed.     

Quantum dots in photonic molecules and quantum informatics. Part I

The main types, fabrication technologies, and physical characteristics of photonic molecules are reviewed. The spectra and spatial configurations of molecular eigenmodes are analyzed within the tight-binding model. Experimental methods for studying the properties of photonic molecules and controlling their states with the use of various external devices are described in detail.     

基于光电倍增管单光子脉冲幅度分布的多比特光量子随机源

提出并验证了一种基于光电倍增管单光子脉冲高 度分布的多比特光量子随机源。将紫外LED发出 的光衰减成离散的单光子序列,光电倍增管探测到的单光子后,输出脉冲幅度随机分布的单 光子脉冲,通 过数字化单光子脉冲的峰值作为熵源来提取随机数,实现了一个单光子事件产生多个随机比 特位。为减小 所提取原始随机数存在的偏差,提出并实现了基于FPGA的SHA-256后 处理方法。光量子随机源工作在 500kc/s时,平均每个探测光子可提取7bit随机位,获得了3.5Mbit/s的随机位产生速率。运用随机性 测试程序ENT和STS对所获的随机位序列进行测试,测试结果表明,序列的随机性满足真随机 数的标准。     

Wired and single sideband wireless service based on a single optical modulator

In order to provide more flexible and convenient service for users in the hybrid transmission network,a novel system using a single optical modulator to provide wired and single side band (SSB) wireless signal was proposed.By combining the application of dual-polarization binary phase shift keying modulator (DP-BPSK),phase shifter and other devices,wired and SSB wireless signals were directly generated to suppress the walk-off effect caused by dispersion,and the effective transmission of 5 Gbit/s SSB wireless signal carried on 40 GHz millimeter wave and 10 Gbit/s wired signal over 65 km single-mode fiber (SMF) were successfully achieved.The experiments show that the application of polarization multiplexing technology and optical subcarrier multiplexing technology can make the signal have a greater improvement in transmission rate and performance,and play an important role in the future broadband communication network.     

基于MATLAB的单光阱光镊中光阱力的分析

在几何光学近似下,对米氏球状粒子所受轴向光阱力进行了数值计算。仿真结果给出了轴向稳定捕获区域和光阱力与光镊系统主要参数的关系。分析表明,激光束束腰半径越小,势阱越深;相对折射率、激光波长、功率等参数对光阱力也有一定影响。数值仿真为实验中参数的选择提供了依据。     

基于全光纤M-Z干涉仪的单通道光开关研究

为了实现高性能的光开关器件,提出了在马赫-曾德尔干涉仪的一端连上光纤布喇格光栅构成单通道光开关器件的方法,并针对该器件进行了理论模拟研究和实验验证,得出了该器件在波长1550nm处的光开关输出谱。结果表明,该器件具有结构简单、易于实现和性能良好等优点。     

Investigation of deep traps in silicon–germanium epitaxial base bipolar transistors with a single polysilicon quasi self-aligned architecture

The electrical properties of Si/Si_1−xGe_x bipolar transistors have been analysed at temperatures ranging from 77 to 500 K. The investigated SiGe base transistors were fabricated using a BiCMOS single-polysilicon quasi self-aligned process, where base implant had been replaced by selective epitaxy on the base active area. At low temperature, static current–voltage measurements show a degradation of base current ideality, whereas collector current remains ideal over the whole temperature range. By studying forward and reverse currents at emitter–base and base–collector junctions, we have established that deep levels were involved in conduction phenomena at these junctions. Detailed measurements using capacitance transient spectroscopy (with different reverse and filling pulse voltages and different filling pulse durations) have revealed the presence of two deep levels along the periphery of the emitter. These deep levels have been found with identical characteristics at both junctions. It is demonstrated that these traps are most probably induced by the extrinsic base implantation.     

基于单片机的多功能温度测量仪表的设计

介绍了一种基于单片机控制的集测量与变送一体化的多功能数字温度测量仪表.该测温仪将热电偶和温度指示仪表以及变换发送单元集成在一起,采用便携式结构.它不仅可以就地安装,用作温度测量的指示与变送单元,而且,还可以随身携带,用作普通温度测量仪表.现详细介绍其软硬件组成和工作原理.     

双波泵浦量子阱子带共振跃迁的非线性光学性质

设计了组分为Al_(0.5)Ga_(0.5)As/GaAs/Al_(0.2)Ga_(0.8)As阶梯形量子阱结构,其导带子带能级可与中红外双波长CO_2激光器的泵浦光光子能量共振.计算了此量子阱对两束泵浦光的二阶非线性差频系数χ_(DFG)~((2))及三阶非线性系数χ_(ω1)~((3))和χ_(ω2)~((3))的表达式;在导带分别为抛物线形和非抛物线形两种条件下,对比研究了三个非线性系数随两束泵浦光波长的变化.χ_(DFG)~((2))、χ_(ω1)~((3))和χ_(ω2)~((3))随两束泵浦光波长λ_(p1)和λ_(p2),都是呈现出先增大后减小的变化趋势,对应不同泵浦波长,存在一个峰值;相比于导带为抛物线形,在非抛物线条件下三个非线性系数随短波长的泵浦光λ_(p1)的变化出现"红移"现象,而随长波长的泵浦光λ_(p2)的变化峰值位置基本相同;由量子限制效应导致的两种导带情况下子带能级变化,即与泵浦光光子共振条件发生变化,是出现"红移"的原因;而峰值数值上的差异,主要由量子阱子带能级间的跃迁矩阵元和两种导带条件下不同的能级差决定.     

Analytic results for the base region of bipolar transistors based on computer simulations

Empirical formulae for effective base Gummel number (including dopant dependent mobility and band-gap reduction effects), effective mobility (with integrated band-gap narrowing) and transit time as functions of the accessible parameters of pinched base sheet resistance and junction depths are studied. The results are verified using numerical analysis on a range of actual fabricated devices.     

Improving optical properties of CdTe quantum dots by a new multidentae biopolymer based on salep

In this work, we have successfully modified aqueous CdTe quantum dots (QDs) by a biopolymer based on poly (2-hydroxyethyl methacrylate) grafted onto salep via a facile method at room temperature. The obtained QDs were characterized using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TG), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The size of the prepared QDs was estimated around 1.5 nm by TEM and XRD. Optical properties of modified QDs were monitored by absorption and fluorescence spectrophotometers. It was found that the fluorescence intensity of CdTe QDs was enhanced after coating by biopolymer. Finally, the fluorescence intensity of CdTe QDs was investigated at different temperatures and times.     

Experimental analysis of a photovoltaic concentrator based on a single reflective stage immersed in an optical fluid

This article reviews all the experimental tests carried out to analyze the performance of a FluidReflex photovoltaic concentrator. This novel concentrator concept consists of a single reflective stage immersed in an optical fluid. The presence of the fluid entails significant advantages. It not only allows a high system optical efficiency and increases the attainable concentration but also enhances the heat dissipation from the cell. In addition, the electrical insulation is improved, and the problem of water vapor condensation inside the module is avoided. A complete characterization is addressed in this paper. Among the experimental results, a measured optical efficiency of 83.5% for a concentration of 1035× stands out. Copyright © 2013 John Wiley & Sons, Ltd.     

Research of all-optical ultra-wideband triplet signal source based on a single semiconductor optical amplifier

A novel scheme for all-optical ultra-wideband triplet signal pulse generation based on the cross-gain modulation (XGM) in a single semiconductor optical amplifier (SOA) is demonstrated. In this scheme, only one optical source and one SOA are needed, so the configuration is simple. Due to only one wavelength is included in the generated triplet pulse, no time difference between output signal light and probe light is introduced during the transmission process. By using the software of Optisystem 7.0, the impacts of the input signal width, the optical power and the wavelength of the optical source on the generated triplet pulse are numerically simulated and studied. The results show that the proposed scheme has better triplet signal pulse when the input signal pulse width is larger, and it is insensitive to the wavelength change within a certain range.     

基于FPGA的计算机多媒体光纤传输设计与实现

为了满足计算机主机和外设在电磁屏蔽环境中电磁隔离的要求,提出了一种基于FPGA的光纤传输系统的设计方案.在ISE12.3开发环境下,采用Verilog语言,结合数字化技术与光纤传输技术,在四层PCB板上实现了计算机多媒体信号(VGA视频、音频等信号)在光纤中远距离低损耗的高速实时传输.     

基于单光子探测的目标光学散射特性研究

研究了目标物体的单光子散射回波特性,基于红外单光子探测器和皮秒激光器搭建了目标光学散射特性测量系统,以回波光子数作为单光子条件下目标光学散射特性的表征。实验研究了不同形状（球体、立方体、圆柱体、圆锥体）目标物体的单光子散射特性,并利用双向反射分布函数模型对实验结果进行拟合,理论拟合结果与实验测量结果能够很好地吻合。进一步对不同材质（瓷砖、木材、外墙砖）目标物体的单光子散射特性进行了研究,并将实验结果与传统波动散射特性进行了对比分析。该研究为单光子激光雷达远距离目标识别与探测的相关工作提供了参考。