Memory-assisted measurement device-independent quantum key distribution with parametric down-conversion sources

The memory-assisted measurement device-independent quantum key distribution (MDI-QKD), which requires less stringent conditions on the memory modules than that of quantum repeaters scheme, offers a practical mid-term solution to long-distance quantum key distribution. In this paper, considering the high cost and the high multi-photon probability, respectively, of single-photon source (SPS) and weak coherent source (WCS), we present schemes on implementing the parametric down-conversion sources, including the heralded single-photon source (HSPS) and single-photon-added coherent source (SPACS), in the memory-assisted MDI-QKD. By numerical simulations, we show that HSPS and SPACS scheme have apparent superiorities both in the key generation rate and the required minimal coherence time of quantum memory compared to WCS scheme. Moreover, we find that the robustness of SPACS against intensity fluctuations is better than WCS, but still worse than HSPS.     

面向对象技术在纤维图像处理中的应用

利用面向对象程序设计（OOP）技术创建了纤维图像专用类CFDib，给出了该类的详细定义，由于该类具有良好的兼容性和可扩充性，因而具有实际推广的价值。     

Methods for characterizing CRT displays

Computer-controlled CRT displays can be described by a two-stage model. The first stage consists of a linear transformation matrix relating radiometric scalars of each channel with either spectral radiance or tristimulus values. The second stage is non-linear and relates digital counts with the radiometric scalars for each channel. The term system gamm, Γ, is introduced to define the non-linear stage. Γ can be characterized by either direct measurement or using a theoretical model with gain, k_g, offset, k_o, and exponential, γ, parameters. Techniques and recommendations are given both to determine the transformation matrix coefficients and estimate Γ using several methods. Special attention is given to Macintosh imaging systems. Key issues include channel and spatial independence tests, including optical flare due to internal reflections, and problems arising from preset video look-up table entries.     

Deriving Spectral, Reflectance Functions of Computer-Simulated Object Colours

A method is presented which, given the RGB values of a colour stimulus displayed on a given cathode ray tube (to which a CIE XYZ triple corresponds), makes it possible to find a spectral reflectance function characterizing an object colour. Such an object when “illuminated” by a given illuminant produces a metameric spectral power distribution, that is, one with the same XYZ tristimulus values. The method is useful in the colorimetric matching of colours on different media or supports.     

设备无关量子通信综述(英文)

Quantum communications helps us to enhance the security and efficiency of communications and to deepen our understanding of quantum physics. Its rapid development in recent years has attracted the interest of researchers from diverse fields such as physics, mathematics, and computer science. We review the background and current state of quantum communications technology, with an emphasis on quantum key distribution, quantum random number generation, and a relatively hot topic: device independent protocols.     

数码喷射印花中的色彩管理

阐述了数字喷射印花的色彩管理,分析了色彩管理中的颜色空间,包括与设备有关的RGB颜色空间和CMYK颜色空间,以及与设备无关的L*a*b*颜色空间;分析了色彩管理的原理以及ICC色彩管理系统;并对描述设备颜色特征的设备Profile文件的建立方法作了一定的介绍。通过本文可以看到色彩管理是数字喷墨印花中一个重要的印前环节。     

Mach的I／O系统

ＭａｃｈＩ／Ｏ系统采用了和ＵＮＩＸ完全不同的概念和结构。Ｍａｃｈ设备管理围绕端口和存储对象这两个Ｍａｃｈ基本概念进行,提供了方便的ＰＲＣ用户界面。Ｍａｃｈ３．０的Ｉ／Ｏ系统新进展将Ｉ／Ｏ管理作为用户Ｓｅｒｖｅｒ对待。本文介绍了Ｍａｃｈ设备管理机制、“设备独立”的驱动程序的构造原理及其例子、在用户空间对设备的直接控制方法和引进新概念后设备管理的性能情况。