Λ型三能级原子诱导光机械系统的稳态纠缠

为了研究原子对光机械系统的影响,将原子引入到一个双模动腔系统中,本文提出了一个由Λ型三能级原子去纠缠两个介观镜以及双模腔场的理论方案。由于原子的介入,使得腔场与移动的镜子之间发生相互作用。利用量子朗之万方程,结合激光的线性近似理论,求出此系统的稳态解。同时,采用西蒙判据,对系统的稳态纠缠进行了数值模拟。研究结果表明,纠缠是由原子的相干态诱导的,即使对于机械品质因子较低的坏腔,当腔场与原子之间的耦合系数取值恰当时,两个移动的镜子,两模腔场以及腔场与较远镜子之间都会产生纠缠。并且得出,耦合系数越大,纠缠越大,即入射率越大,纠缠越大。由于在此混合系统中,任何两体之间都是纠缠的,得出此系统中存在多体纠缠现象。     

多声子系统的多光机械诱导透明

提出了一个光学腔中包含三个可移动镜子的混合腔光机械系统的理论方案,这个光学腔被一束较强的耦合场和一束较弱的探测场驱动与三个机械振子线性耦合.利用平均场近似理论,得到系统的稳态解,并数值模拟了系统输出的探测场随失谐的变化关系.分析与数值结果显示,当三个机械振子的振动频率互不相等时,该系统出现三个透明窗口,当三个振子的振动频率两两相等、或三个都相等时,三透明就变成了双透明或单一透明窗口;同时发现,在所选取的参数范围内,腔场与振子之间的有效耦合系数及腔场的衰减率能够调控透明窗口的宽度,有效耦合系数越大或衰减率越小,透明窗口越宽;如果腔中存在N个机械振子,当N个机械振子的频率互不相等时,此系统会出现N透明现象,否则,透明窗口的个数会有所减少.     

级联原子诱导的腔光力系统的稳态纠缠特性

本文提出了一个由三能级级联原子束去纠缠双模腔场的理论方案。利用量子朗之万方程,结合激光的线性近似理论,求出此系统的稳态解。同时,采用Negativity作为纠缠判据,对系统的稳态纠缠进行了数值模拟。研究结果表明,纠缠是由原子的相干态诱导的,即使对于机械品质因子较低的坏腔,当参数取值恰当时,两模腔场以及腔场与镜子之间也都会产生纠缠。并且得出,入射率越大,纠缠越大。     

基于多模腔光力系统的纠缠研究

基于由3个机械振子模和单模腔场组成的四模腔光力系统提出实现任意两个玻色模间稳态纠缠的理论方案.利用光学腔模和腔内3个机械振子模相互作用,通过调制驱动腔模的光场,获得系统类分束器相互作用有效哈密顿量,进而实现对非定域Bogoliubov模的冷却,并获得任意双模间的稳态纠缠.利用数值模拟方法系统讨论了振子频率、振子耗散、外驱动场对稳态纠缠的影响,结果表明:振子间频率适当的失谐有利于增强彼此间的纠缠,与压缩效应相比冷却效应起主导作用,这和三模腔光力系统中冷却效应和压缩效应相互竞争不同.     

基于三腔光力系统的单向放大器

单向放大器是经典和量子信息处理中非常重要的非互易性器件.提出了一种基于三腔光力系统实现单向放大器的方案,其中3个不同的腔场通过辐射压力分别耦合于1个共同的机械振子,并且有2个腔直接耦合起来便于实现非互易性传输.通过求解线性化的量子郎之万方程,解析地给出了实现单向放大的条件,并详细研究了不同腔模之间传输的透射率随入射信号的频率以及有效光力耦合强度的大小和相位差等物理量变化的情况.研究发现,该系统在机械振子的增益和量子相干效应的共同作用下可以实现信号的单向放大.     

三能级原子—双模动腔系统的纠缠输出

本文考虑了一个三能级原子与双模动腔系统相互作用的理论方案.通过量子朗之万方程给出了系统的稳态解,并得出入射率(耦合系数)增大,光子数变少;利用输入输出理论,数值模拟了两模腔场之间的纠缠压缩谱.研究表明原子的入射率及镜子的振动频率影响双模场的输出压缩谱.     

三能级原子与双模动腔系统的稳态求解

在原子与双模动腔共同存在的量子系统中,原子、腔场以及移动的镜子之间都会发生相互作用.考虑了一个三能级原子与双模动腔所组成的光机械系统,应用量子朗之万方程,讨论了由V型三能级原子束与双模动腔组成的系统中稳态解的求解方法.由所求的结果可看出,原子介质的存在能影响光子的有效衰减率以及腔场和两个镜子之间的辐射压.     

基于光机械系统的质量探测器

光机械系统在精密测量方面的应用关键是基于纳米机械振子与高品质光学腔之间的强耦合.利用光学腔耦合纳米机械振子的同时通过库伦力耦合另外的一个带电纳米机械振子,并利用双模光力诱导透明等量子特性,发现第二个纳米机械振子随着附加质量的不断增加,两个透明窗口之间的距离(透射光频率之差)不断减小,根据此关系可精密测量附加在第二个纳米机械振子上微小物体质量.     

耗散准模腔场与激子相互作用的量子统计性质

研究了耗散准模腔场与激子相互作用的量子统计特性 ,给出了当腔场初始处于真空态而激子处于真空态与粒子数态大于 2的叠加态时的腔场与激子能量交换的表达式。研究结果表明 ,激子和腔场可以呈现亚泊松分布状态 ,激子与腔场之间的关联是经典的 ,不存在Cauchy Schwartz不等式的偏离现象。     

双模SU(2)相干态场与一个Λ型三能级原子共振相互作用系统的光场反聚束效应

采用全量子理论和数值计算方法,研究了初始处于SU(2)相干态的双模腔场与一个人型三能级原子共振相互作用系统的光场反聚束效应.讨论了在没有对原子进行态选择测量和直接对原子进行态选择测量的两种情况下,两个腔模总光子数、配分参量、耦合系数和原子初态对光场反聚束效应的影响.结果表明:当两个腔模的耦合系数相同时,光场的两个模都呈现反聚束效应;原子初始处于低能级或直接对原子进行态选择测量,α模的反聚束效应明显增强;减少两个腔模的总光子数M,光场的反聚束效应明显增强;当两个腔模的耦合系数相同并对原子进行态选择测量时,光场的反聚束效应不随时间改变.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to