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The distributions of limit cycles of cubic vector fields (P2, Q3) are considered in this paper, where P2 and Q3 are polynomials of x and y of order two and three, respectively. It is possibly seven different distributions of limit cycles given in [1]. We now prove that in which three kinds of distributions are impossible and other four kinds all can be realized by concrete vector fields of (P2,Q3). Some related results are also given. 相似文献
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电荷转移器件(CTD_s)在原子发射光谱中的应用(Ⅰ) 总被引:1,自引:0,他引:1
本文分三部分对国内外原子发射光谱的固态光学多道检测系统特别是电荷转移器件(CTD_s)检测器近10年来的发展进行了综合评介。集中讨论了CTD_S的工作原理、性能特征及其在原子发射光谱中应用的几个具体方面。共引用文献108篇。本篇为其中的第一部分,主要讨论CTD_s的工作原理及性能特征。 相似文献
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在包含三能级原子的环形腔的输出光场中, 观察到了由电磁感应透明(EIT) 效应导致的动态非稳及混沌. 该动态非稳及向混沌的过渡可以通过耦合光场而加以很好地控制. 同时, 由三能级EIT导致的原子相干改变了系统的吸收、色散及非线性效应, 从而极大地增强了系统的动态非稳和混沌过渡特性. 建立了一个理论模型来定量地解释观察到的现象. 相似文献
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半导体量子点主要包括在真空中外延生长的自组织量子点和在溶液中采用化学方法合成的胶体量子点,由于量子限制效应所导致的分立能级结构使得它们通常被称为“人工原子”。和自然原子不同,半导体量子点的能级结构强烈依赖于其尺寸和形状,这样就提供了更为灵活的方法来控制固体材料中的光与材料的相互作用。近年来,许多类原子的量子光学现象(包括量子干涉、Rabi振荡和Mollow荧光)都已经在单个的自组织量子点中揭示出来。与此形成对比的是,上述所有的类原子量子光学特性目前还没有在单个的胶体量子点中观察得到。在本文中,我们将侧重于介绍我们科研组以及我们和别的科研组合作对单个自组织量子点的单量子态在光学探测和相干控制方面完成的一系列工作。对单个的胶体量子点,我们认为量子相干特性的测量和控制将在新近合成的非荧光闪烁或荧光闪烁得到抑制的材料体系中得以实现. 相似文献
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In blind quantum computation (BQC), a client with weak quantum computation capabilities is allowed to delegate its quantum computation tasks to a server with powerful quantum computation capabilities, and the inputs, algorithms and outputs of the quantum computation are confidential to the server. Verifiability refers to the ability of the client to verify with a certain probability whether the server has executed the protocol correctly and can be realized by introducing trap qubits into the computation graph state to detect server deception. The existing verifiable universal BQC protocols are analyzed and compared in detail. The XTH protocol (proposed by Xu Q S, Tan X Q, Huang R in 2020), a recent improvement protocol of verifiable universal BQC, uses a sandglass-like graph state to further decrease resource expenditure and enhance verification capability. However, the XTH protocol has two shortcomings: limitations in the coloring scheme and a high probability of accepting an incorrect computation result. In this paper, we present an improved version of the XTH protocol, which revises the limitations of the original coloring scheme and further improves the verification ability. The analysis demonstrates that the resource expenditure is the same as for the XTH protocol, while the probability of accepting the wrong computation result is reduced from the original minimum (0.866)d* to (0.819)d*, where d* is the number of repeated executions of the protocol. 相似文献
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在包含三能级原子的环形腔的输出光场中,观察到了由电磁感应透明(EIT)效应导致的动态非稳及混沌.该动态非稳及向混沌的过渡可以通过耦合光场而加以很好地控制.同时,由三能级EIT导致的原子相干改变了系统的吸收、色散及非线性效应,从而极大地增强了系统的动态非稳和混沌过渡特性.建立了一个理论模型来定量地解释观察到的现象. 相似文献
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Quantum metrology holds the promise of improving the measurement precision beyond the limit of classical approaches.To achieve such enhancement in performance requires the development of quantum estimation theories as well as novel experimental techniques.In this article,we provide a brief review of some recent results in the field of quantum metrology.We emphasize that the unambiguous demonstration of the quantum-enhanced precision needs a careful analysis of the resources involved.In particular,the implementation of quantum metrology in practice requires us to take into account the experimental imperfections included,for example,particle loss and dephasing noise.For a detailed introduction to the experimental demonstrations of quantum metrology,we refer the reader to another article’Quantum metrology’in the same issue. 相似文献
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选取我院收治的乳腺癌(BC)患者82例设为研究组,同期乳腺良性肿瘤患者82例设为对照组,探讨了超声参数联合血清骨桥蛋白(OPN)、白细胞介素-1β(IL-1β)对BC的诊断价值.结果显示,研究组患者病灶处的RI值、PI值和血清OPN、IL-1β水平均高于对照组(P<0.05);PI值、RI值、血清OPN、IL-1β水平... 相似文献