Three-qubit Phase Gate in a Five-level Tripod Atomic System

We propose a scheme for the realization of three-qubit phase gate in a five-level tripod atomic system, based on the cross phase modulation among three weak fields under the condition of electromagnetically induced transparency （EIT）. Three weak fields are coupling three ground states to the lower excited state, while a strong control field is acting on the transition between the lower and upper excited states, forming three adjacent Ladder configurations. This scheme can be realized in s7 Rb atoms confined in a vapor cell or magneto-optical trap. The enhanced fifth order optical nonlinearity with negligible absorption is obtained by slightly disturbing the exact two-photon resonance condition yet remaining within the EIT window. The generated large nonlinearity can produce nonlinear phase shifts of order or, which can be used to realize three-qubit polarization phase gate. The proposed three-qubit phase gate should have potential applications in quantum information processing.     

高Al组分AlGaN多量子阱结构材料发光机制探讨

紫外LED的发光功率和效率还远不能令人们满意,波长短于300 nm的深紫外LED的发光效率普遍较低。厘清高Al组分Al Ga N多量子阱结构的发光机制将有利于探索改善深紫外LED的发光效率的新途径、新方法。为此,本文通过金属有机气相外延技术外延生长了表面平整、界面清晰可辨且陡峭的高Al组分AlGa N多量子阱结构材料,并对其进行变温光致发光谱测试,结合数值计算,深入探讨了Al Ga N量子阱的发光机制。研究表明,量子阱中具有很强的局域化效应,其发光和局域激子的跳跃息息相关,而发光的猝灭则与局域激子的解局域以及位错引起的非辐射复合有关。     

热脱附-气相色谱-质谱法同时测定工作场所空气中10种醇类和醚类化合物的含量北大核心CSCD

通过对比填充不同吸附剂的不锈钢吸附管对10种醇类和醚类化合物的吸附能力,优化热脱附条件,考察不同色谱柱和样品保存时间对测定结果的影响,提出了热脱附-气相色谱-质谱法同时测定工作场所空气中10种醇类和醚类化合物含量的方法。用填装Tenax GR的吸附管采集气体样品,采集完成后将吸附管两端封好,设置一次热脱附温度为220℃,二次热脱附温度为240℃,吹扫时间为4 min,进样时间为50 s,在上述条件下进行热脱附,脱附的气体进入气相色谱仪,采用DB-624毛细管色谱柱分离目标物,并用配电子轰击离子源的质谱仪在选择离子监测模式下检测。结果显示:10种醇类和醚类化合物的质量在10~300 ng内与其对应的峰面积呈线性关系,检出限(3.143s)为0.5~1.9 ng;对空白样品进行3个浓度水平的加标回收试验,回收率为70.5%~125%,测定值的相对标准偏差(n=6)为1.0%~20%;方法用于实际样品分析,正丁醇、异丁醇和仲丁醇被检出,检出量依次为0.013,0.007,0.008 mg·m^(-3)。     

AlGaN-Based Deep-Ultraviolet Light Emitting Diodes Fabricated on AlN/sapphire Template

We report on the growth and fabrication of deep ultraviolet （DUV） light emitting diodes （LEDs） on an AIN template which was grown on a pulsed atomic-layer epitaxial buffer layer. Threading dislocation densities in the AlN layer are greatly decreased with the introduction of this buffer layer. The crystalline quality of the AlGaN epilayer is further improved by using a low-temperature GaN interlayer between AlGaN and AlN. Electroluminescences of different DUV-LED devices at a wavelength of between 262 and 317nm are demonstrated. To improve the hole concentration of p-type AlGaN, Mg-doping with trimethylindium assistance approach is performed. It is found that the serial resistance of DUV-LED decreases and the performance of DUV-LED such as EL properties is improved.     

碳纳米管/Nafion-吡啶钌修饰电极电化学发光法测定激动素

实验发现激动素对固定于碳纳米管/Nafion复合膜修饰电极上的吡啶钌弱电化学发光信号有强的增敏作用,基于此建立了一种高灵敏的电化学发光直接测定激动素的新方法.在优化的实验条件下,本方法测定激动素的线性范围为5.0×10-8～4.0×10-5g/L;检出限为2.0×10-8 g/L;相对标准偏差(RSD)为5.8% (n=11, c=5×10-6 g/L);方法操作简单方便,灵敏度高.     

二介质激光放大器工作特性的数值模拟

从简明的物理模型出发，首次从理论上模拟了二介质激光放大器的工作特性，表明它能够同时满足输出高能量，超短脉冲放大的要求。对实验中可能遇到的问题进行了模拟，并提出了解决的方法。     

软X射线分光晶体琥珀酸氢十四酯的合成及结晶习性研究

本文合成了软X射线分光晶体琥珀酸氢十四酯(THS).通过红外光谱、差示量热扫描等手段对所合成样品进行表征和鉴定.对THS在苯、甲苯、二甲苯、异丙醇等溶剂中的自发成核和结晶形态进行了研究,结果表明THS在苯、甲苯和二甲苯中表现出良好的结晶习性.采用平衡法测定了THS在苯、甲苯和二甲苯中的溶解度曲线.综合考虑结晶习性和溶解度情况,可选择甲苯作为晶体生长的溶剂进行单晶生长实验.     

高血压病患者的左房室构型与功能变化

目的：探讨高血压病患者左房室及功能变化的相互关系。方法：采用超声多普勒技术研究３４０例高血压病患者的左房室构型及心功能变化。结果：高血压病患者左房室按正常构型、单纯左房增大、向心性左室重构、向心性左室肥厚、离心性左室肥厚分型。其所占比例集资为６３．５３％、５．８８％、３．２４％、１４．４１％、１２．９４％。构型改变多出现在５年以上病程患者,且与病程呈正相关,收缩功能减退出现在左室肥厚的后期,而舒张     

施太可治疗心律失常的剂量探讨

目的：探索国人应用施太可（索他洛尔）治疗心律失常的疗效和合适剂量。方法：对５３例非心肌梗塞的心律失常患者采用施太可治疗,分别不同剂量（４０～２４０ｍｇ／ｄ）,观察疗效及不良反应,用临床及动态心电图进行评定。结果：（１）栓部５３例患者应用施太可治疗后,总有效３９例,总有效率达７３．５８％。（２）３９例有效病例平均剂量为９３．５７ｍｇ／ｄ。（３）应用小剂量施太可后ＱＴｃ延长及心率减慢均有显著差异,但对