单分散性SiO2小球的制备及表征

以四乙氧基硅烷为原料,以氨水为催化剂,采用Sol-gel反应合成了单分散性SiO_2小球。结果表明,通过控制原料及氨水的浓度,可以对小球的粒径(70～1 000 nm可调)进行控制;采用红外光谱、固体核磁共振、X射线衍射、扫描电镜及透射电镜等分析手段对小球的结构和形貌进行了表征。结果表明小球具有较为致密的实心结构,基本实现了无机化,并且具有较好的热稳定性能。     

采用双模压缩态的光子纠缠光纤陀螺仪研究CSCD

对采用双模压缩态的光子纠缠光纤陀螺仪进行了理论研究,采用角动量理论首次推导了双模压缩态输入的光子纠缠光纤陀螺仪的相位检测灵敏度,并证明了当光子数足够大时,可以达到海森堡极限。针对采用双模压缩态的光子纠缠光纤陀螺仪的二阶符合计数探测方案远未达到海森堡极限的情况,通过考察光子纠缠光纤陀螺仪各输出态的二阶符合计数对总的二阶相关光强的贡献,发现二阶符合计数探测方案存在量子增强信息的抵消,也即其中一个接收端光子数为偶数的输出态和光子数为奇数的输出态的二阶符合计数形成互补的倍频干涉条纹,进而相互抵消。因此,需要优化探测方案,提取完整的量子增强信息,才能实现海森堡极限的相位检测灵敏度。     

Laser time transfer and its application in the Galileo programme

We are presenting the new instrument, new technology available and new measurement technique proposal for the Galileo programme – optical detector for the laser time transfer and one way laser ranging ground to space.     

基于量子纠缠的空间信息传输系统研究

量子通信是一种无条件安全的信息传输方式. 提出了一种基于量子纠缠的空间信息系统. 该系统以平流层平台和地球同步卫星为量子中继站, 分发纠缠光子对. 利用量子纠缠在发信者与收信者之间建立通信链路, 使用量子隐形传态进行量子信息传输. 讨论了该空间信息系统的特性, 并对其信息传输性能进行了数值分析. 结果表明该系统能够安全有效地传输空间信息.      

多通道高计数率单光子计数系统的设计与实现

光子计数探测具有极高的探测灵敏度，已成为大气探测激光雷达的主流探测手段。设计了一种基于FPGA的8通道高计数率单光子计数系统，提出了一种基于多相时钟过采样的光子脉冲检测方法，实现了2 ns的光子脉宽分辨率、200 MCPS的光子计数率、无死时间的连续多通道同步计数，具有高计数率、高实时性、高集成度的特点。系统已装备于北京遥测技术研究所研制的多波长拉曼偏振大气探测激光雷达中，在激光雷达大气遥感中发挥了重要作用。     

Mission analysis and performance comparison for an Advanced Solar Photon Thruster

The so-called “compound solar sail”, also known as “Solar Photon Thruster” (SPT), is a design concept, for which the two basic functions of the solar sail, namely light collection and thrust direction, are uncoupled. In this paper, we introduce a novel SPT concept, termed the Advanced Solar Photon Thruster (ASPT), which does not suffer from the simplified assumptions that have been made for the analysis of compound solar sails in previous studies. After having presented the equations that describe the force on the ASPT and after having performed a detailed design analysis, the performance of the ASPT with respect to the conventional flat solar sail (FSS) is investigated for three interplanetary mission scenarios: an Earth–Venus rendezvous, where the solar sail has to spiral towards the Sun, an Earth–Mars rendezvous, where the solar sail has to spiral away from the Sun, and an Earth-NEA rendezvous (to near-Earth asteroid 1996FG3), where a large change in orbital eccentricity is required. The investigated solar sails have realistic near-term characteristic accelerations between 0.1 and 0.2 mm/s². Our results show that an SPT is not superior to the flat solar sail unless very idealistic assumptions are made.     

量子光谱成像技术及其在对地观测中的应用前景

综述了量子光谱成像技术的发展概况,简述了量子光谱成像原理的理论,详细介绍了纠缠双光子源的鬼成像,亚波长干涉以及热光的无透镜成像和热光的非定域双缝干涉实验及其原理。最后对量子光谱成像技术在未来的军用和民用对地观测的应用方面做出了展望。     

Photon counting detector for space debris laser tracking and lunar laser ranging

We are reporting on a design, construction and performance of solid state photon counting detector package which has been designed for laser tracking of space debris. The detector has been optimized for top photon detection efficiency and detection delay stability. The active area of the commercially available avalanche photodiode manufactured on Si (SAP500 supplied by Laser Components, Inc.) is circular with a diameter of 500 μm. The newly designed control circuit enables to operate the detection sensor at a broad range of biases 5–50 V above its breakdown voltage of 125 V. This permits to select a right trade-off between photon detection efficiency, timing resolution and dark count rate. The photon detection efficiency exceeds 70% at the wavelength of 532 nm. This is the highest photon detection efficiency ever reported for such a device. The timing properties of the detector have been investigated in detail. The timing resolution is better than 80 ps r.m.s, the detection delay is stable within units of picoseconds over several hours of operation. The detection delay stability in a sense of time deviation of 800 fs has been achieved. The temperature change of the detection delay is 0.5 ps/K. The detector has been tested as an echo signal detector in laser tracking of space debris at the satellite laser station in Graz, Austria. Its application in lunar laser ranging is under consideration by several laser stations.     

Dispersion-free quantum clock synchronization via fiber link

We proposed a fiber-based quantum clock synchronization protocol by employing the dispersion cancellation feature of the frequency anti-correlated entangled source under the quantum interference measurement. It is shown that, the accuracy of the synchronization is mainly dependent on the bandwidth of the frequency entangled biphoton spectrum and on the temperature variation induced fluctuations in both the reference fiber coiling and the fiber link. With this proposal, synchronization between two clocks at a distance of ten kilometers can be implemented with an accuracy below a picosecond.     

Lorentz Symmetry breaking studies with photons from astrophysical observations

Lorentz Invariance Violation (LIV) may be a good observational window on Quantum Gravity physics. Within last few years, all major gamma-ray experiments have published results from the search for LIV with variable astrophysical sources: gamma-ray bursts with detectors on-board satellites and Active Galactic Nuclei with ground-based experiments. In this paper, the recent time-of-flight studies with unpolarized photons published from the space and ground based observations are reviewed. Various methods used in the time delay searches are described, and their performance discussed. Since no significant time-lag value was found within experimental precision of the measurements, the present results consist of 95% confidence level limits on the Quantum Gravity scale on the linear and quadratic terms in the standard photon dispersion relations.