Generation of four-photon W state via cavity QED

This paper proposes an alternative scheme for generating four-photon W state via cavity QED. The scheme bases on the resonant interaction of a A-type three level atom with two bimodal cavities. The detection of atom collapses the cavity to the desired state. Comparing with previous schemes, the advantage of this scheme is that the interaction time can be greatly shortened since it uses the resonant interaction between atom and cavities. Moreover, the proposed scheme is more experimentally feasible than the previous ones.     

Absolute small-angle measurement based on optical feedback interferometry

We present a simple but effective method for small-angle measurement based on optical feedback interferometry （or laser self-mixing interferometry）. The absolute zero angle can be defined at the biggest fringe amplitude point, so this method can also achieve absolute angle measurement. In order to verify the method, we construct an angle measurement system. The Fourier-transform method is used to analysis the interference signal. Rotation angles are experimentally measured with a resolution of 10^-6 rad and a measurement range of approximately from -0.0007 to ＋0.0007 rad.     

低能量氦─氖激光静脉内照射血液综合治疗颅脑损伤

对２５例不同程度颅脑损伤患者进行低能量氦—氖激光静脉内照射血液综合治疗结果表明，低能量激光血管内照射血液（ＩＬＩＢ）具有显著疗效。作者还讨论了该疗法可能作用的机制。     

ZnS∶Sm,Y_2O_3∶Eu 和ZnS∶Mn红色交流电致发光薄膜材料和器件的研究

交流驱动的 ZnS:Mn(橙黄色)和 ZnS:TbF_3(绿色)电致发光薄膜(ACELTF)器件已实现商品化生产,目前研制发射红光和蓝光的 ACELTF 材料和器件是平板显示研究领域的前沿课题,其目的是实现彩色和多色 ACELTF 平板显示。ZnS:Sm 和CaS:Eu 两种红色ACELTF 已经进行了比较深入的研究,但由于 ZnS:Sm 色纯度差,亮度低,而 CaS:Eu 虽然     

新版HyperCard具有文本转换成语音及24位功能

上星期公布了苹果计算机有限公司推出的HyperCard 2.3,它所具有的自动功能使新手也可以很容易地进行多媒体开发。 HyperCard是一种多媒体开发工具,用来开发和连接信息库。目前具有自动键任务,24位彩色绘图工具和文本到语音功能。     

噪声门

任何信号中都有噪声,或者说噪声无所不在。当信号很强时,噪声被信号所淹没。当信号很弱时,噪声就现出来了。对音频信号而言,语言和音乐都经常有间歇或停顿。这时噪声就突出出来。噪声门可抑制信号很弱或停顿时的信源背景噪声。可用于吉他或其他乐器的演凑,也可以用于其他场合。 噪声门的电路很简单(见图1),它由一个集成双运放BC548B组成。其中一半ICla组成受信号控制的可变增益放大器,另一半IClb组成控制放大器。二级管D4,D5对IClb放大后的信号进行整流。整流后的电压控制晶     

改进考試方法,发揮学生在学习上的主动性

(一) 怎样引起改进的我们是根据考试的目的来改进考试方法的。对考试目的的认识,我们是有一个过程的。过去,把考试当作推动学生学习的法宝,认为学生学不好,就要考,把它当成强迫学生学习的一种手段,同时,把考试作为检查学生学习质量的唯一手段,认为考试越突然,就越能看出学生的真正水平。基于这些错误认识,伴随而来的就是考试多,采取突然袭击,其结果造成学生过分紧张与畏惧的情绪,造成精神上的沉重负担,学     

光电直读发射光谱的某些新进展

引言自火焰分析法问世一百多年以来,仪器分析,尤其是原子发射光谱分析(AES),虽然几经波折,但得到了突飞猛进的发展,对促进科学技术的开发,做出了积极的贡献。而科学技术的发展,又推进了发射光谱分析技术的不断创新。实用光谱分析仪器中,在看谱镜、摄谱仪和照相测光方法的基础上,Hasler于     

Strongly Correlated Effect in TiS2

The thermoelectric compound TiS2 is studied by using the full-potential linearized augmented plane-wave method on the density functional theory with the generalized gradient approximation （GGA） as well as the on-site Coulomb interaction correction （＋U）. The Seebeck coefficient of TiS2 is calculated based on the electronic structure obtained within the GGA under the consideration of the on-site Coulomb interaction. The calculated Seebeck coefficient at 300K shows that Coulomb interaction U in the range of 4.97-5.42eV is important to reproduce the experimental data. The obtained energy gap Eg around 0.05 eV indicates that TiS2 is an indirect narrow-gap semiconductor.