共查询到20条相似文献,搜索用时 140 毫秒
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大角度巴巴散射和双μ产生的研究与亮度测量 总被引:1,自引:0,他引:1
利用北京谱仪(BES)在S=4.03GeV下正负电子对撞数据,研究了巴巴和双μ事例的QED过程.结果表明,实验数据在误差范围内同QED预言较好地一致,且从e+e-和μ+μ-末态测出的两亮度值在4%范围内相互一致.计算给出:BES在该能区获取数据的总积分亮度为23.1pb-1. 相似文献
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利用北京谱仪(BES)在北京正负电子对撞机(BEPC)e+e-对撞质心系能量为4.03GeV处收集的积分亮度为22.3pb-1的数据,测量了带电及中性D介子的单举半轻子(电子)衰变的分支比.分析中采用了“联合D0和D+单双标记”的方法,测得D-和D0单举半轻子(电子)衰变的分支比分别为BF(D-→e-X)=(21.8±8.5±4.2)%,BF(D0→e-X)=(8.9±3.0±1.6)%,其相对比值为BF(D-→e-X)BF(D0→e-X)=2.4±1.7±0.8. 相似文献
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研究了北京谱仪(BES)Ⅱ带电径迹测量误差矩阵的修正,使运动学拟合TELESIS方法在BESⅡ物理数据分析中得到应用.1)在BESⅡ数据重建程序中,加入了适当的MDC重建单丝分辨率(250μm)和Q修正.2)在TELESIS程序中,放入了BESⅡ有效物质量对BESⅡ误差矩阵进行多次库仑散射和dE/dX能损效应的修正.3)在此基础上,通过J/ψ→μ+μ-的数据样本分析,完成了BESⅡ24×106J/ψ事例RUN-by-RUN的误差矩阵刻度,同时对BESⅡMC数据也作了相应的刻度.经上述误差矩阵修正后,BESⅡ的TELESIS可以较好地满足BESⅡ数据分析工作的要求. 相似文献
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分析北京谱仪(BES)收集的4.03GeV质心系能量下e+e-对撞数据,选出e+e-→τ±τ+→e±X+v′S事例,X±可以为μ±,τ±,ρ±,拟合τ→ev′s中电子的能谱,得到τ→ev′s中Michel参数为ρτ→e=0.705,此结果与标准模型的预言相符合. 相似文献
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Measurements of the lepton polarization and forward-backward polarization asymmetry near the Z resonance using the OPAL detector are described. The measurements are based on analyses of and decays from a sample of 144,810 candidates corresponding to an integrated luminosity of 151 pb. Assuming that the lepton decays according to V–A theory, we measure the average polarization near to be and the polarization forward-backward asymmetry to be , where the first error is statistical and the second systematic. Taking into account the small effects of the photon propagator,
photon-Z interference and photonic radiative corrections, these results can be expressed in terms of the lepton neutral current asymmetry
parameters:
These measurements are consistent with the hypothesis of lepton universality and combine to give . Within the context of the Standard Model this combined result corresponds to . Combing these results with those from the other OPAL neutral current measurements yields a value of .
Received: 5 March 2001 / Published online: 6 July 2001 相似文献
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A. E. Afanasiev P. N. Melentiev A. A. Kuzin A. Yu. Kalatskiy V. I. Balykin 《Journal of Experimental and Theoretical Physics》2017,125(3):372-383
The localization and transport of a photon through a subwavelength hole with the help of a neutral atom are studied. A method proposed and realized in the study is based on the absorption of a photon by a neutral atom directly in front of a subwavelength hole, the flight of the atom through the hole, and photon emission on the other side of the screen. The influence of the interaction of the excited atom flying through the subwavelength channel with the screen material is estimated. The estimate showed that the atomic excitation can be quenched in holes with diameters smaller than 200 nm, which affects the photon transport efficiency. 相似文献
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We propose a new system of quantum bits generation using a soliton pulse within a micro ring resonator. A quantum gate can be formed using a polarization control unit incorporating into the system. The random signal and idler pairs can be formed within the photon correlation bandwidth, which can be generated and randomly formed the packet quantum bits, i.e. quantum packet codes. Each random code (logic) can be performed by combining the signal and idler of each entangled photon pair via the quantum gate. Results obtained have shown that the packet of quantum logic bits can be generated using the entangled photon pairs generated by the proposed system. The quantum bits transmission fidelity and error corrections are also described. 相似文献
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采用两路光子时间到达点构建光纤式光子计数伪随机码深度获取系统.为了研究降低深度误差的方法,以高斯函数为激光回波脉冲,计算瞬时概率密度函数,引入"时间行走"效应数学模型,推导深度误差克拉美罗下限.随着激光回波能量的增大,深度误差先降低再增大,并且码长越长,深度误差越小.采用理论推导的累积分布函数,生成光子时间到达点,蒙特卡洛仿真伪随机序列光子探测过程,结果大于理论数值模拟,符合克拉美罗下界原理.17组标定实验表明:由于目标表面特性的不同而导致探测到激光回波中光子数的浮动,该浮动引发光子"时间行走"效应,并带来伪随机码深度获取系统的互相关函数的整体偏移.采用数值拟合方程拟合不同光子计数比例值下的深度误差,测量得到的光子计数比例值,代入拟合的矫正方程,矫正后的深度均方误差下降至1cm. 相似文献
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A new diagnostic method using both techniques of neutral beam probing and laser-induced fluorescence (LIF) is proposed to measure electron density (1011-1013 cm-3) and electron temperature (1-100 eV) of a boundary layer plasma in devices like tokamaks. The local electron density can be obtained by measuring the photon flux of the resonance line produced by electron impact excitation of an injected neutral Li-beam which is produced by laser-induced evaporation (LIE). The density of the neutral Li-beam which is necessary for the determination of the electron density is measured by LIF. The local electron temperature can be obtained by determining the attenuation of two neutral beams (Li, and Al or Ti) produced by LIE, of which the measurements are carried out by means of LIF. The applicability of this method to the TEXTOR tokamak is discussed in detail. 相似文献
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Accuracy analysis of centroid calculated by a modified center detection algorithm for Shack-Hartmann wavefront sensor 总被引:1,自引:0,他引:1
The accuracy of the Shack-Hartmann wavefront sensor for measuring the wavefront distortion is mainly dependent upon the measuring accuracy of the centroid of each spot. A modified center detection algorithm, which uses some power from the photon events of each pixel instead of photon events themselves, is analyzed theoretically and the computer simulations are given. The results show that photon noise error and sampling error increases as the power value goes up; and to some powers, the readout noise and background noise error decrease. An experiment is described through which the optimum power can be obtained. 相似文献
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单光子的衰减特性及其易受干扰的缺点限制了纯单光子量子系统的传输码率及距离.弱相干光脉冲(WCP)光源和准单光子源(HSPS)则具有更高的实用价值.本文将这两种光源和诱发态方案相结合并采用Lütkenhaus和Gottesman-Lo- Lütkenhaus-Preskill (GLLP)两种数据后处理方法进行性能分析.仿真结果表明:HSPS在传输距离上要优于WCP,对应相同传输距离时系统量子误码率(QBER)要小些,但相对密钥生成率低.
关键词:
量子密钥分配
诱发态
WCP光源
HSPS光源 相似文献
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为实现Solar Blind(日盲紫外)滤光片光密度在可见光谱段的高精度连续测试,搭建了以氙灯配合单色仪作为光源、使用单光子计数器作为探测器的测试系统,并对该系统的误差进行分析。系统主要装置有氙灯与单色仪组合的光源,标准衰减装置和单光子计数器;以替代法为基础进行测试,将由单光子计数器探测到的衰减后的计数值作为参考计数值替代光源的初始计数值,通过运算得到滤光片的可见光谱段光密度;该测试系统将滤光片光密度的测试动态范围扩展到0~-11OD,实现了可见光谱段内进行连续光谱测量的功能,且降低了系统的测试误差。与使用窄带LED作为光源的测试系统相比,测试不确定度由2%降低至0.5%,相对重复性误差由0.2% 降低至0.13%。 相似文献
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Peng Wang Zheng Zhang Chang-Qi Yu Rui-Yang Yuan Fang-Fang Du Bao-Cang Ren 《Annalen der Physik》2023,535(4):2200505
The information content of a photon system can be extended by hyperentanglement, but the quality of hyperentanglement will be decreased by the complicated transmission loss and channel noise in quantum information processing. Here, an efficient measurement-based hyperentanglement distillation protocol (MB-HDP) is presented for depressing the effects of complicated transmission loss and channel noise on hyperentanglement. In the MB-HDP, the nonlocal lossy and distortion photon states are coupled to local hyperentangled Greenberger–Horne–Zeilinger (GHZ) states using parity measurement and qubit amplification device, and the decoherence caused by bit-flip (phase-flip) error, diverse transmission coefficients and transmission loss can be depressed by the successful measurement results, which can increase the quality of nonlocal hyperentangled photon state. This MB-HDP broadens the application scope of hyperentanglement distillation to nonlocal lossy and distortion photon state with a lower degree of entanglement. In addition, the MB-HDP can further improve the quality of nonlocal hyperentangled photon state by coupling multiple copies of lossy and distortion hyperentangled photon state with local hyperentangled GHZ states. This work demonstrates the ability of measurement-based method for ensuring the quality of nonlocal hyperentanglement, which can improve the integrity and capacity of long-distance quantum information processing. 相似文献