量子光通信

量子光通信是以量子信息论和量子力学为理论基础的一种全光型通信，是正处于开发之中的现代光通信前沿．本文简明地介绍了量子光通信的基本概念与特征，阐明了在这种通信系统中一个光子可将无限的信息传递给无限个分支终端．量子光通信系统分为三个关键性部分，即亚泊松激光器、量子非破坏测量和光子计数器．本文对它们的工作原理、基本特性等分别作了介绍，指出了它们的现状和发展前景．     

高强混凝土弯压极限应变试验研究与计算

由于混凝土材料理化特性的差异,高强混凝土的弯压极限应变明显地小于普通混凝土,依据试验结果分析了高强混凝土的弯压极限应变变化规律,并给出了它的计算公式.     

具有微观应变纳米晶体铜的HRTEM研究

纳米晶体材料因具有许多不同于常规晶体材料的性能而受到广泛关注。已有研究表明 :纳米晶体材料的性能不仅与其晶粒尺寸有明显的依赖关系 ,而且会因纳米晶粒之间的晶界区结构的不同有非常明显的变化 ,即纳米晶体材料的晶粒及晶界微观结构对其性能产生重要的影响。近期在用Ｘ射线衍射对磁控溅射法制备的纳米晶体Ｃｕ的研究中发现[1] :制备态的纳米晶体Ｃｕ样品中存在着较大微观应变 (0 2 4 % ) ;经 110℃ 30ｍｉｎ退火后 ,样品的晶粒尺寸无明显长大 ,但微观应变明显减小 (0 14 % )。与制备态的纳米晶体Ｃｕ相比 ,退火态样品的热膨胀系数增…     

胶球研究现状

本文介绍了有关胶球研究的现状,重点介绍确认胶球的一些定性的判据以及实验上已发现的一些可能的胶球候选者.     

Realization of Greenberg-Horne-Zeilinger （GHZ） and W Entangled States with Multiple Superconducting Quantum-Interference Device Qubits in Cavity QED

An alternative scheme is proposed for generating the Greenberg-Horne-Zeilinger （GHZ） and W types of the entangled states with multiple superconducting quantum-interference device （SQUID） qubits in a single-mode microwave cavity field. In this scheme, there is no transfer of quantum information between the SQUIDs and the cavity, the cavity is always in the vacuum and thus the requirement on the quality of cavity is greatly loosened. In addition, during the process of the generation of the W entangled state, the present method does not involve a real excitation of intermediate levels. Thus, decoherence due to energy relaxation of intermediate levels is minimized.     

An Economical Magnetocardiogram System Based on High-To SQUIDs

An economical magnetocardiogram （MCG） system is built in our laboratory. It mainly consists of a MCG data acquisition stage equipped with two high-To superconducting quantum interference device （SQUID） magnetometers, a data processing stage with digital filtering and a one-layer μ-metal magnetically shielded room in conjunction with a high-Tc SQUID based active compensation. Experimental results show that a noise level of pico-tesla in MCG profiles, which is necessary for clinical applications, may be achieved with the system. Moreover, stable and convenient operations of the system are demonstrated with simulating MCG measurements.     

Controlled Bidirectional Quantum Direct Communication by Using a GHZ State

A controlled bidirectional quantum secret direct communication scheme is proposed by using a Greenberger- Horne-Zeilinger （GHZ） state. In the scheme, two users can exchange their secret messages simultaneously with a set of devices under the control of a third party. The security of the scheme is analysed and confirmed.     

多孔硅发光机制的分析

从量子力学的基本理论出发讨论了量子限制效应，推导出多孔硅有效禁带宽度增量并用量子限制效应和表面态及其物质在发光中作用的理论解释了ＰＳ光致发光的实验现象。     

CdTe／Cd_（1－x）Mn_xTe：In应变层量子阱的光荧光光谱

报道了ＭＢＥ生长的ＣｄＴｅ／Ｃｄ１－ｘＭｎｘＴｅ：Ｉｎ调制掺杂应变层多量子附材料的光荧光光谱，低温下观察到一个由多电子－单个空穴散射引起的很强的费密边奇异的发光现象，对应于费密边能量位置发光峰有一个很强的增加，使整个发光锋具有明显的非对称性．分析讨论了引起费密边奇异现象的物理机制，测量了７７Ｋ下ＣｄＴｅ／Ｃｄ１－ｘＭｎｘＴｅ：Ｉｎ样品的调制光谱，与荧光光谱进行了比较，结果进一步支持了本文的结论．还测量了费密迪奇异随温度的变化，结果表明此现象在Ⅱ—Ⅵ族半导体多量子附材料中比Ⅲ─Ｖ族材料强得多．