量子纠缠是执行量子计算和构建量子通信网络的关键资源,制备与操控纠缠态光场是实现量子信息处理的基础要素.本文提出了利用双端光学腔倍频产生四组份纠缠态的理论模型,从耦合波方程出发得到Ⅱ类倍频过程的传输矩阵,通过腔内自再现方程...量子纠缠是执行量子计算和构建量子通信网络的关键资源,制备与操控纠缠态光场是实现量子信息处理的基础要素.本文提出了利用双端光学腔倍频产生四组份纠缠态的理论模型,从耦合波方程出发得到Ⅱ类倍频过程的传输矩阵,通过腔内自再现方程和输入输出传输矩阵理论研究了输出的两束倍频光的噪声特性;对于两束倍频光和两束基频泵浦场,利用多组份纠缠光场的充分必要判据PPT方法(positivity under partial transposition criterion)分析了最小辛本征值与泵浦功率及分析频率之间的关系,研究结果表明基频泵浦光与倍频光之间存在四组份纠缠.展开更多
Simple and efficient surface acoustic wave （SAW） two-port resonators with low insertion loss and high Q-values on ST-X quartz substrate using a corrosion-proof A1/Au-stripe electrode structure are developed for gas ...Simple and efficient surface acoustic wave （SAW） two-port resonators with low insertion loss and high Q-values on ST-X quartz substrate using a corrosion-proof A1/Au-stripe electrode structure are developed for gas sensing. It was composed of two shorted grating reflectors and adjacent intedigital transducers （IDT）, and an active metal film in the cavity between the IDTs for the sensitive film coating. The devices are expected to provide good protection towards metal electrode for gas sensors application in chemically reactive environments. Excellent device performance as low insertion loss, high Q factor and single-mode are achieved by carefully selecting the metallic electrode thickness, cavity length and acoustic aperture. Prior to fabrication, the coupling of modes （COM） model was performed for device simulation to determine the optimal design parameters. The fabricated single-mode SAW resonator at operation frequency of 300 MHz range exhibits matched insertion loss of ~6.5 dB and loaded Q factor in the 3000 range. Using the fabricated resonator as the feedback element, a duaresonator-oscillator with excellent frequency stability （0.1 ppm） was developed and evaluated experimentally, and it is significant for performance improvement of SAW gas sensor.展开更多
为实现能源多梯度利用并减少环境污染,气-电耦合的综合能源系统(integrated energy system,IES)逐渐占据全球能源结构的重要部分。为明晰系统运行特性并充分挖掘能源子网调度潜力,综合能源系统动态仿真研究逐渐深入。天然气网中,管道传...为实现能源多梯度利用并减少环境污染,气-电耦合的综合能源系统(integrated energy system,IES)逐渐占据全球能源结构的重要部分。为明晰系统运行特性并充分挖掘能源子网调度潜力,综合能源系统动态仿真研究逐渐深入。天然气网中,管道传输过程深刻影响着其动态过程。然而现有管道传输过程时域仿真算法存在着精度与效率的两难。为解决上述问题,提出一种基于时域二端口模型的综合能源系统气网动态仿真算法。首先基于特征线法,构建气网源荷节点关系矩阵,进一步给出时域二端口模型;随后参考特征线法数值格式,构建状态量空间分布矩阵,用于获取气网状态量分布,并提出基于时域二端口模型和分布矩阵的气网动态仿真算法。算例结果表明,所提出的方法具有高效率和高精度两大优势,适合于气-电耦合的综合能源系统的较长时间仿真。展开更多
THE low-noise preamplifier, as one of the major circuits in signal detection system, consists ofthe low noise amplifier and the feedback network. The low noise amplifier design aims both tocalculate the optimal source...THE low-noise preamplifier, as one of the major circuits in signal detection system, consists ofthe low noise amplifier and the feedback network. The low noise amplifier design aims both tocalculate the optimal source impedance and minimum noise figure, and to compare the noiseperformance and other characteristics of variant circuits and components. The conventional ap-proach to noise analysis of an electronic circuit is to calculate the output noise power of the展开更多
The startup process of a thermoacoustic engine is a self-excited oscillation process generated in inhomogeneous acoustic media. To reveal these coupling relations between various influential factors is an important ta...The startup process of a thermoacoustic engine is a self-excited oscillation process generated in inhomogeneous acoustic media. To reveal these coupling relations between various influential factors is an important task of basic research on thermoacoustics. In this paper thermoacoustic engines are regarded as thermoacoustic oscillators consisting of the active network and the passive network. Accordingly, the two-port Y-parameter for relevant component is derived, and standing wave and traveling wave thermoacoustic engine are described by the negative-resistance and feedback model, respectively. The relevant two-port network topology is given as well. The startup criteria for thermoacoustic oscillators are obtained by using Nyquist instability criterion. The model prediction of startup parameters, particularly, startup frequency and mode characteristic are in agreement with that of experimental results reported in the literature. Moreover, with topological graphs it is verified that standing wave engines would start up in a negative-resistance state and there would exist high frequency modes in thermoacoustic-Stirling engines. By investigating into the frequency response of thermoacoustic system, this method proposed can achieve such an objective that these effects of operating and structural parameters of engine on startup modes and startup temperature can be revealed in an analytical way. Thus this approach to test and check thermal stability can be provided in a design phase, instead of using empirical frequency to design thermoacoustic systems.展开更多
文摘量子纠缠是执行量子计算和构建量子通信网络的关键资源,制备与操控纠缠态光场是实现量子信息处理的基础要素.本文提出了利用双端光学腔倍频产生四组份纠缠态的理论模型,从耦合波方程出发得到Ⅱ类倍频过程的传输矩阵,通过腔内自再现方程和输入输出传输矩阵理论研究了输出的两束倍频光的噪声特性;对于两束倍频光和两束基频泵浦场,利用多组份纠缠光场的充分必要判据PPT方法(positivity under partial transposition criterion)分析了最小辛本征值与泵浦功率及分析频率之间的关系,研究结果表明基频泵浦光与倍频光之间存在四组份纠缠.
基金supported by the National Nature Science Foundation of China(11074268,10834010)
文摘Simple and efficient surface acoustic wave （SAW） two-port resonators with low insertion loss and high Q-values on ST-X quartz substrate using a corrosion-proof A1/Au-stripe electrode structure are developed for gas sensing. It was composed of two shorted grating reflectors and adjacent intedigital transducers （IDT）, and an active metal film in the cavity between the IDTs for the sensitive film coating. The devices are expected to provide good protection towards metal electrode for gas sensors application in chemically reactive environments. Excellent device performance as low insertion loss, high Q factor and single-mode are achieved by carefully selecting the metallic electrode thickness, cavity length and acoustic aperture. Prior to fabrication, the coupling of modes （COM） model was performed for device simulation to determine the optimal design parameters. The fabricated single-mode SAW resonator at operation frequency of 300 MHz range exhibits matched insertion loss of ~6.5 dB and loaded Q factor in the 3000 range. Using the fabricated resonator as the feedback element, a duaresonator-oscillator with excellent frequency stability （0.1 ppm） was developed and evaluated experimentally, and it is significant for performance improvement of SAW gas sensor.
文摘为实现能源多梯度利用并减少环境污染,气-电耦合的综合能源系统(integrated energy system,IES)逐渐占据全球能源结构的重要部分。为明晰系统运行特性并充分挖掘能源子网调度潜力,综合能源系统动态仿真研究逐渐深入。天然气网中,管道传输过程深刻影响着其动态过程。然而现有管道传输过程时域仿真算法存在着精度与效率的两难。为解决上述问题,提出一种基于时域二端口模型的综合能源系统气网动态仿真算法。首先基于特征线法,构建气网源荷节点关系矩阵,进一步给出时域二端口模型;随后参考特征线法数值格式,构建状态量空间分布矩阵,用于获取气网状态量分布,并提出基于时域二端口模型和分布矩阵的气网动态仿真算法。算例结果表明,所提出的方法具有高效率和高精度两大优势,适合于气-电耦合的综合能源系统的较长时间仿真。
文摘THE low-noise preamplifier, as one of the major circuits in signal detection system, consists ofthe low noise amplifier and the feedback network. The low noise amplifier design aims both tocalculate the optimal source impedance and minimum noise figure, and to compare the noiseperformance and other characteristics of variant circuits and components. The conventional ap-proach to noise analysis of an electronic circuit is to calculate the output noise power of the
基金Supported by National Natural Science Foundation of China (Grant Nos. 50576024 and 51076013)
文摘The startup process of a thermoacoustic engine is a self-excited oscillation process generated in inhomogeneous acoustic media. To reveal these coupling relations between various influential factors is an important task of basic research on thermoacoustics. In this paper thermoacoustic engines are regarded as thermoacoustic oscillators consisting of the active network and the passive network. Accordingly, the two-port Y-parameter for relevant component is derived, and standing wave and traveling wave thermoacoustic engine are described by the negative-resistance and feedback model, respectively. The relevant two-port network topology is given as well. The startup criteria for thermoacoustic oscillators are obtained by using Nyquist instability criterion. The model prediction of startup parameters, particularly, startup frequency and mode characteristic are in agreement with that of experimental results reported in the literature. Moreover, with topological graphs it is verified that standing wave engines would start up in a negative-resistance state and there would exist high frequency modes in thermoacoustic-Stirling engines. By investigating into the frequency response of thermoacoustic system, this method proposed can achieve such an objective that these effects of operating and structural parameters of engine on startup modes and startup temperature can be revealed in an analytical way. Thus this approach to test and check thermal stability can be provided in a design phase, instead of using empirical frequency to design thermoacoustic systems.
