The Quantum Coherence Effects in Degenerate Two-level Atomic System

The quantum coherence effects of the transition Fe = 2←→Fg = 3 depending on the polarization of the coupling and probe beam are observed in a Cs vapor cell. The splitting of electromagnetically induced transparency （EIT） window is observed when the degeneracy of two-level system is broken using a magnetic field. It is also shown that the splitted transparency points of two of three windows are shifted with the intensity of magnetic field （ i. e. Zeeman splitting in the upper and lower levels ） increasing. On the contrary, when we fix the intensity of magnetic field, and increase the Rabi frequency of the coupling beam, the splitted transparency peaks become wider. A qualitative agreement between experiment and theory is found.     

需求变化的多阶段EOQ订购策略

多阶段库存管理是供应链研究的重要课题,其中独立需求的订购策略问题,现有文献一般设定计划期内各阶段需求且计划执行过程中需求不再变化,给出了相应的算法.本文选择EOQ模型作为基本订购策略,研究下面一类需求变化的多阶段订购策略问题：给定费用参数（物资单价、一次订货费用、单位库存保管费用）的情况下,在订购计划执行过程中,在阶段i（1＜i＜m）需要调整阶段m的需求,而其它阶段的需求不变,订购策略如何调整,使得库存总费用最低.     

Au/SiO2纳米多层薄膜的制备及其性质表征

利用多靶磁控溅射技术制备了Au/SiO2纳米颗粒分散氧化物多层复合薄膜.研究了在保持Au单层颗粒膜沉积时间一定时薄膜厚度一定、变化SiO2的沉积时间及SiO2的沉积时间一定而改变薄膜厚度时,多层薄膜在薄膜厚度方向的微观结构对吸收光谱的影响.研究结果表明:具有纳米层状结构的Au/SiO2多层薄膜在560nm波长附近有明显的表面等离子共振吸收峰,吸收峰的强度随Au颗粒的浓度增加而增强,在Au颗粒浓度相同的情况下,复合薄膜光学吸收强度随薄膜厚度的增加而增强.但当金属颗粒的浓度增加到一定程度时,金属颗粒相互接触,没有观察到纳米层状结构,薄膜不显示共振吸收峰特征.用修正后的M-G(Maxwell-Garnett)理论对吸收光谱进行了模拟,得到了与实验一致的结果.     

可集成量子计算中的非近邻相互作用

我们研究一维自旋1／2链中的非近邻相互作用的影响。和近邻相互作用相比，非近邻的相互作用强度一般会较弱，因而在以前的许多方案中，这种长程的相互作用被忽略了。本文首先估计由被忽略的非近邻相互作用所引起的量子逻辑门的误差。我们得到的结果是，这项误差不仅和非近邻相互作用的强度有关，更依赖于一维自旋链所包含的粒子数，忽略非近邻相互作用有可能会对可集成量子计算造成影响。我们进一步研究如何消除或者压缩这种长程的相互作用所造成的影响。我们提出了一个量子计算方案。在这种方案中，次近邻的相互作用的影响被完全消除，从而我们可以使量子逻辑门的精度得以提高。我们也讨论了这种方案在超导量子计算体系里面的物理实现问题。     

Realization of the Fredkin Gate by Three transition Pulses in a Nuclear Magnetic Resonance Quantum Information Processor

We have experimentally realized the Fredkin gate with only three transition pulses in a solution of alanine.It appears that no experimental realization of the Fredkin gate with fewer pulses has been reported yet.In addition,the simple structure of our scheme makes it easy to implement in experiments.     

量子力学创始人海森伯生平简介

 2001年12月5日是量子力学创始人之一海森伯诞辰100周年纪念日。这一天在海森伯成长和工作多年的慕尼黑市组织了有多位世界著名物理学家参加的纪念活动。     

Micro-Photoluminescence Investigation of Single Quantum Dot and its Molecule of CdSe/ZnSe

The single and a few coupled quantum dots are important for future quantum information sciences and their investigation is also a big challenge in physics. We investigate here the electronic and exciton states and their interaction with each other via micro photoluminescence. The luminescence for single and a few dots as well as a dot molecule of CdSe/ZnSe are measured with very high resolution, under liquid He temperature and magnetic fields and with different polarization of excitation laser. The observed sharp spectral lines are attributed to the atomlike transitions of exciton, trion, biexciton… in the investigated single QD or QD molecule. Band filling, Zeeman splitting, spin transition and their relaxation are observed and investigated＇from the spectra and compared with those of same material in different dimensions, and compared with the primary calculation as well. In addition, quite a few new phenomena, which can not be understood based on our present model and knowledge, are also observed; and some very interesting problems are left for further investigation.     

Theoretical Research on a Kind of Quantum Left-handed Metamaterial

Recently, research on left-handed materials （LHMs） has attracted considerable attentions. The LHMs are a kind of metameterial which have negative permittivity and negative permeability, which lead to negative refractive index in a frequency range. The LHMs that have been available so far are in the microwave range and are usually composed of classical particles, such as split-ring resonators. Some quantum phenomena such as spontaneous emission of atoms in the LHMs which are considered to be ＇classical background＇ have also been investigated. Many potential applications of LHMs have been proposed, such as superlenses which, in principle, can achieve arbitrary subwavelength resolution.     

量子位Heisenberg XX开链中边界量子位之间的纠缠

Heisenberg 开链对研究量子态在自旋链上的传递有重要的意义.本文研究了五量子位Heisenberg XX 开链中边界量子位之间的纠缠，在该系统中引入了磁杂质和系统杂质且它们之间满足线性关系时，该系统可以精确求解，此时边界量子位之间存在纠缠.选择合适的杂质参数和磁场参数，该边界纠缠的最大值可达到0.5. 关键词： Heisenberg XX开链 边界纠缠 杂质     

带干扰的多险种风险模型

由于保险公司风险经营规模不断扩大,用单一险种的模型来描述风险过程存在局限性,本文讨论了带干扰多险种风险模型,应用鞅论方法,得出伦德伯格不等式和最终破产概率公式。