共查询到20条相似文献,搜索用时 0 毫秒
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JIANG Yunkun Li Jian SHI Baosen FAN Xiaofeng GUO Guangcan 《Chinese Journal of Lasers》2000,9(5):464-468
1 Introduction Inquantumcommunicationandquantumcompution ,two statesystemshavebeenusedtoencodeaquantumbitinformationandwetraditionallyrepresentthetwoquantumstatesby 0〉and 1〉 ,respectively .A quantumbitcanberepresentedbyasingle particlesystem ,andtwoquantumb… 相似文献
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By using phase space method, we theoretically investigate the quantum statistical properties and quantum interference of optical parametric amplification of single photon. The statistical properties, such as the Wigner function (WF), average photon number, photon number distribution and parity, are derived analytically for the fields of the two output ports. The results indicate that the fields in the output ports are multiphoton states rather than single photon state due to the amplification of the optical parametric amplifiers (OPA). In addition, the phase sensitivity is also examined by using the detection scheme of parity measurement. 相似文献
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Single photon detection (SPD) with high quantum efficiency has been widely used for measurement of different quantum states with different photon distributions.Based on the direct single SPD and double-SPD of HBT configuration, we discuss the effect of a real SPD on the photon statistics measurement and it shows that the measured photon distributions for different quantum states are corrected in different forms.The results are confirmed by experiment with the strongly attenuated coherent light and thermal light.This system can be used to characterize the photon statistics of the fluorescence light from single atom or single molecular. 相似文献
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基于0.18μm CMOS工艺技术,制作了单光子雪崩二极管,可对650~950nm波段的微弱光进行有效探测.该器件采用P~+/N阱结构,P~+层深度较深,以提高对长光波的光子探测效率与响应度;采用低掺杂深N阱增大耗尽层厚度,可以提高探测灵敏度;深N阱与衬底形成的PN结可有效隔离衬底,降低衬底噪声;采用P阱保护环结构以预防过早边缘击穿现象.通过理论分析确定器件的基本结构参数及工艺参数,并对器件性能进行优化设计.实验结果表明,单光子雪崩二极管的窗口直径为10μm,器件的反向击穿电压为18.4V左右.用光强为0.001 W/cm~2的光照射,650nm处达到0.495A/W的响应度峰值;在2V的过偏压下,650~950nm波段范围内光子探测效率均高于30%,随着反向偏压的适当增大,探测效率有所提升. 相似文献
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A. Drezet 《Foundations of Physics Letters》2006,19(5):459-470
In the paper with the above title [1] (but without the question mark), it is claimed that quantum nonlocality can be revealed
in a simple interferometry experiment using only single particle. A critical analysis of the concept of hidden variable used
by the authors of [1] shows that the reasoning is not correct. 相似文献
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Polarization properties of single photons emitted by optical pumping from a single quantum dot ( QD) are studied by using a four-level system model. The model is capable of explaining the polarization uncertainty observed in single photon emission experiments. It is found that the dependence of photon emission efficiency and polarization visibility on pump power are opposite in general cases. By employing QDs with small size and strong carrier confinement, the photon polarization visibility under high pump power can be improved. In addition, embedding a QD into a well designed microcavity is also found to be favourable, whereas the trade-off between high polarization visibility and multi-photon emission is noted. 相似文献
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高探测效率CMOS单光子雪崩二极管器件 总被引:1,自引:0,他引:1
基于标准0.35μm CMOS工艺设计了一种单光子雪崩二极管器件.采用p+n阱型二极管结构,同时引进保护环与深n阱结构以提高单光子雪崩二极管性能;研究了扩散n阱保护环宽度对雪崩击穿特性的影响;对器件的电场分布、击穿特性、光子探测效率、频率响应等特性进行了分析.仿真结果表明:所设计的单光子雪崩二极管器件结构直径为10μm,扩散n阱保护环宽度为1μm时,雪崩击穿电压为13.2 V,3 dB带宽可达1.6 GHz;过偏压为1 V、2 V时最大探测效率分别高达52%和55%;在波长500~800 nm之间器件响应度较好,波长为680 nm时单位响应度峰值高达0.45 A/W. 相似文献
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In this talk, the interaction of a single photon injected to a single atom is studied, for which initially the photon is uncorrelated with the atom. The spontaneous emitted photon will then evolve to be entangled with the atom on their continuous kinetic variables (momentum) in the process of resonant scattering. We find the relations between the entanglement and their physical control parameters (such as the linewidth of the injected photon wave packet, and that of the atomic wave packet, etc. ), which indicates that high entanglement can be reached by broadening the scale of the atomic wave or squeezing the linewidth of the incident single-photon pulse. 相似文献
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基于相对论流体力学,指出了新近报道的首次实测的纯光子谱虽然具有线性,但并不意味着极端相对论性原子核碰撞后的系统在整体上达到了热平衡. 运用动态相变机制的计算结果可以预言,若强子化相变是一级相变,当碰撞能量高于200GeV/u时,纯光子谱将呈现凹形曲线,可以用作诊断夸克-胶子等离子体是否存在的信号. 相似文献
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We propose an experimental scheme to realize the four-dimensional projective measurements tor a single photon. The photon polarization and time-energy provide the four-dimensional Hilbert space. Based on this scheme, we suggest an experiment to test the violation of Bell inequalities of four-dimensional systems. In addition, by virtue of a maximally entangled biphoton state, we also show that it is possible to construct a quantum key distribution channel that can provide two-bit key with one pair of entangled photons. 相似文献
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《中国物理快报》2016,(8)
Increasing the detection efficiency(DE)is a hot issue in the development of the superconducting nanowire single photon detector(SNSPD).In this work,a cavity-integrated structure coupled to the SNSPD is used to enhance the light absorption of nanowire.Ultra-thin Nb films are successfully prepared by magnetron sputtering,which are used to fabricate Nb/Al SNSPD with the curve of 100 nm and the square area of 4×4μm~2 by sputtering and the lift-off method.To characterize the optical and electrical performance of the cavity-integrated SNSPD,a reliable cryogenic research system is built up based on a He~3 system.To satisfy the need of light coupling,a packaging structure with collimator is conducted.Both DE and the dark count rates increase with I_b.It is also found that the DE of SNSPD with cavities can be up to 0.17% at the temperature of 0.7 K under the infrared light of 1550 nm,which is obviously higher than that of the SNSPD directly fabricated upon silicon without any cavity structure. 相似文献
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Nonlocal character of entangled photon pairs generated in spontaneous parametric downconversion is demonstrated. One photon from a pair propagates through a Mach-Zehnder interferometer and is detected in coincidence-count measurement with its twin. Width of the coincidence-count interference pattern (measured for various values of path difference in the Mach-Zehnder interferometer) depends on spectral width of the twin as a result of entanglement of photons in a pair. The experimental setup is analyzed for a Gaussian spectral filter and a Fabry-Perot resonator. It is shown that nonlocal interference is much stronger for cw pumping in comparison with femtosecond pulsed pumping for values of parameters commonly used in spontaneous parametric downconversion experiments. 相似文献
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Inspired by results of interfering signal and idler from a nondegenerate parametric amplifier we investigate the photon statistics of the resulting field after interference of two components subjected to double-mode two-photon absorption. This absorption process leads to a strong correlation of the participating modes, which can be used to generate fields with photon antibunching in interference experiments. In addition the photon number can be made small, which produces enhanced antibunching. 相似文献