Unconventional geometric phase gate and multiqubit entanglement for hot ions with a frequency-modulated field

We present an alternative scheme for implementing the unconventional geometric two-qubit phase gate and preparing multiqubit entanglement by using a frequency-modulated laser field to simultaneously illuminate all ions. Selecting the index of modulation yields selective mechanisms for coupling and decoupling between the internal and the external states of the ions. By the selective mechanisms, we obtain the unconventional geometric two-qubit phase gate, multiparticle Greenberger--Horne--Zeilinger states and highly entangled cluster states. Our scheme is insensitive to the thermal motion of the ions.     

汕尾市品清湖沉积环境特征分析

汕尾市品清湖是我国目前最大的沿岸泻湖,作者首次对其进行了实地精确测量,面积为23.16km2,湖岸线长39.62km.前人对品清湖的研究认为品清湖潮汐类型属于混合潮中的不正规日潮型,本文测量计算潮汐系数F为1.1,认为该区域的潮汐类型属于混合潮中的不正规半日潮型,分析研究品清湖的沉积环境特征对研究我国沿岸泻湖的形成演化具有典型的示范意义.本文通过对品清湖水文动力、泥沙运移、沉积年代的研究,在对品清湖地质背景、形成演化过程、地形地貌特征、环境动力特征等分析的基础上,对47个表层沉积物样品进行了粒度组分等分析,全面了解品清湖沉积物的类型、粒度组成及特征,沉积物分布、分区及来源等沉积环境特征.分析结果显示品清湖沉积物主要由黏土、粉砂、砂以及砾石组成,沉积物类型可以分为黏土质粉砂、砂质粉砂、粉砂质砂、砾质砂、砂质砾、砂-粉砂-黏土以及砂等7个类型,其中黏土质粉砂是品清湖的主要底质类型.沉积物的来源有多源性或受多种动力因素影响,主要有4种来源,具有典型泻湖港湾沉积的特点,品清湖的底质分区可划分为6个区域,不同的区域反映了不同的物质来源和动力环境.     

粤东深澳湾养殖区域异养细菌和弧菌的动态分布

调查于2007年1月至2008年12月进行,对异养细菌和弧菌丰度的时间和空间分布开展了相关的研究,结果显示深澳养殖海湾水体中以上2种被调查菌类的丰度全年变化范围分别为1.20×105―1.27×108cfu·L-1和1.00×103―3.90×105cfu·L-1;底质中的丰度变化范围分别为2.73×104―4.06×107cfu·g-1和3.25×102―7.23×104cfu·g-1.从时间上来看,营养盐类与异养细菌的相关性要强于温度、盐度、pH值和溶氧等物理因素的相关性;而弧菌与物理因素的相关性要强于与营养盐类的相关性.从空间分布来看水体环境的变化要比底质的大,水体中经常出现异养细菌和弧菌丰度的剧烈变化,变化程度也远远高于底质中细菌的变化.而且不同的养殖活动也会很明显地影响异养细菌和弧菌的丰度:S3站位水体中异养细菌的丰度比底质中的高;S5站位的底质中异养细菌和弧菌的丰度都是较高的.龙须菜的养殖可以很明显地改善底质环境,特别是降低底质中对养殖和水质环境有很大负面影响的生物和非生物因子如硫化物和弧菌等.     

西太平洋暖池近3万年来的沉积序列及其环境特征-WP92-3柱样的REE记录

WP92-3柱样采自西太平洋暖池核心区。利用稀土元素(REE)特征参数研究了该柱样的沉积物来源和地层序列划分,并对其所揭示的环境变化特征进行了探讨。研究认为:样品的REE分布模式揭示了该海域的沉积物源主要为海相自生沉积;基于REE指标的垂向深度变化特征可将该柱样划分为3个地层序列;∑REE,LREE/HREE和δCe几个指标对环境的温度变化以及地磁场的极性变换均有良好的响应,∑REE高值段基本对应于δ18O和SST所揭示的暖池低温期,而地磁场极性转变的时间正好对应着稀土指标(∑REE,LREE/HREE和δCe)快速大幅波动的层位。REE特征参数较好地记录了暖池区近3万年来的沉积和环境变化信息,是一组对气候环境演化具有潜在良好指示作用的地球化学指标。     

利用上海台阵对常熟2001年2002年震群的精定位

2001年6月上海台阵正式运行,上海台阵的建立提高了上海及周边地区的地震监测能力.本文着重在定位方法和震相判读上,充分利用上海台阵整体观测系统的优势和台阵独特的数据处理方法,对常熟2001年和2002年二次小地震序列进行了精确定位.对精确定位的结果进行了对比与分析,并以此为基础,对常熟地区及周边的地质构造等进行了解释与推断.     

论直流激发极化法的视电阻率参数

直流激发极化法,计算视电阻率的一次场采集于供电方波的末端时间,从而包含了被激发形成的二次场。在高极化率地质体上,得到的视电阻率将削弱其低阻特性或放大高阻特性。为此,建议在野外工作中,应对所采集的一次场作适当的处理后,再计算视电阻率,以降低这种影响。     

A note on the deflection of a baroclinic current by a continental shelf

The deflection, at a step-shelf fronted coast, of a constant potential vorticity current in a reduced-gravity, inviscid model ocean is studied theoretically. The step shelf, with a depth smaller than the reservoir depth, forces the uplifting of the approaching current and causes water column foreshortening, leading to relative vorticity generation that enhances current deflection to the right (facing the coast). As a consequence, in comparison to the case of a vertical wall coast, the proportion of the transport to the right is increased. For normal incidence for a shelf-depth/reservoir-depth ratio of 0.3 and shelf width to deformation radius ratio of 1.5, more than 90% of the approaching current transport goes to the right and less than 10% to the left. In addition, the (barotropic) dynamic pressure at the coast is low to the right and high to the left (with the highest pressure at the stagnation point). In the vertical wall case, the wall pressures on the flank are equal. For oblique incidence from the left, the deflection to the left is drastically reduced. In fact, there is practically no steady-state flow diverted to the left (less than 2%) when the approach angle is greater than 60° to the left of normal. In the vertical wall case, the same angle would have to be 90° for the flow to the left to vanish, namely only when the approach current is parallel to the coast to the right.     

Calcite and aragonite precipitation from seawater solutions of various salinities: Precipitation rates and overgrowth compositions

The reaction rate and composition of calcite and aragonite overgrowths precipitated from seawater solutions of various salinities (i.e. S=5, 15, 25, 35, 44) were determined at 25°C and 10^−2.5-atm. CO₂ partial pressure using a constant disequilibrium seeded technique. The rate data were fitted to an empirical rate law of the form:

logR=n(ω_{c(or a)}-1)+logk

where n is the empirical reaction order; and k is the rate constant. Calcite precipitation rates in seawater solutions do not vary appreciably as a result of salinity variations over the range investigated, while those for aragonite show an increase in going from the higher (i.e. S=35, 44) to the lower (i.e. S=5, 15, 25) salinity range. This study also confirms previously published findings that above a given saturation state (i.e. Ω_c>/2.6) aragonite precipitates more rapidly than calcite at 25°C.

The incorporation of Sr²⁺ in aragonite and Mg²⁺ in calcite overgrowths are independent of the precipitation rate. The partition coefficient of Sr²⁺ in aragonite is approximately equal to unity and is unaffected by salinity variations between 5 and 44. However, the Mg²⁺ partition coefficient in calcite, increases with decreasing salinity of the parent seawater solutions, possibly as a result of variations in the sulfate content of the solutions and solids.

The experimental results were discussed in the context of a number of geological environments.     

青藏高原模式大气(暂用)

本文根据青藏高原地区高空温、压、湿的气候资料并参考中纬度与热带模式大气初步建立了青藏高原不同季节的模式大气,以供该地区辐射传输研究的需要。