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1.
Detecting multipartite quantum coherence usually requires quantum state reconstruction, which is quite inefficient for large-scale quantum systems. Along this line of research, several efficient procedures have been proposed to detect multipartite quantum coherence without quantum state reconstruction, among which the spectrum-estimation-based method is suitable for various coherence measures. Here, we first generalize the spectrum-estimation-based method for the geometric measure of coherence. Then, we investigate the tightness of the estimated lower bound of various coherence measures, including the geometric measure of coherence, the -norm of coherence, the robustness of coherence, and some convex roof quantifiers of coherence multiqubit GHZ states and linear cluster states. Finally, we demonstrate the spectrum-estimation-based method as well as the other two efficient methods. We observe that the spectrum-estimation-based method outperforms other methods in various coherence measures, which significantly enhances the accuracy of estimation. 相似文献
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Abstract Recently pulses of the electromagnetic cosmic radiation of varies frequency ranges were detected by means of space flight equipment [1]. But so far the physical nature of the sources of these pulses are not well known. Since the generators of these pulses are at far distances obviously, the latters should have considerable power. But in this case we are forced to accepte that that the radiation is generated not only by the surface but also by the bulk mass of the distant object. It is also reasonable to propose that the objects are superdense ones [2]. In the Latter case the electromagnetic radiation cann't difused up to the surface of a superdense object from the centre and so no electromagnetic and acoustic processes can give radiation from the bulk mass of an object. On the contrary gravitational and neutrino radiation may be generated by the bulk mass of a massive object and at the surface of these objects these radiations tightly bounded to matter may be partly transformed into electromagnetic radiation [3]. And we can suppose that namely this very small part of the whole radiational energy is at time registrated at the earth and space laboratories. The mauy ask why all of the remaining purt of teh rediated energy has not been detected yet? There where made some attempts to performe neutrino astronony equipment out no solar neuttinos have been detected yet. As to the camical gravitational radiation it is pregently inveutigated only at low frequencles and no distinet conclucion about its occurence in been reached in the lilorature. 相似文献
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The dynamics of an electron accelerated by laser radiation with the help of a scheme based on the interference of three relativistically intense electromagnetic pulses with titled amplitude fronts is analyzed. It is shown that, starting at the center of the interference pattern, the electron moves along a spiral trajectory with the axis perpendicular to the wave vectors of the laser beams, gaining considerable kinetic energy in the process. The impact of radiation reaction under the arrangement is simulated numerically in the framework of various approaches intended to take into account the energy loss resulting from the effect. The energy loss by the electron is shown to depend strongly on its initial energy and on whether the electron and the laser pulse initially travel in the same or opposite directions. The relation between small energy losses due to radiation reaction and the electron capture by the optical field is established. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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LUO Deyuan ZHOU Jian TAN Yushan 《Chinese Journal of Lasers》1997,6(6):489-498
ResearchforSignalPowerSpectrumDistributioninLaserDopplerRotationalSpedMeasurementLUODeyuanZHOUJianTANYushan(LaserandInfraredI... 相似文献
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OUYANGBi-Yao ZHANXian-Geng 《理论物理通讯》2001,35(3):360-364
In this paper,we study the dynamic behavior and quasi-energy spectrum of multiband superlattics Bloch electrons in quantum kicked potential.We show analytically and numerically the avoided crossing and band suppression about the quasi-energy spectrum.The dynamic nonlocalization,and the electron oscillation behavior between two bands. 相似文献
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CoherenceTimeMeasurementofPicosecondPulsesUsingReverseSaturableAbsorptioninLeadPhthalocyanineLIFengSONGYinglinYANGKunLUIShuti... 相似文献
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用970CRT荧光分光光度计分别采集了不同pH值下番茄红素-丙酮溶液的荧光光谱,并测量了这些溶液的荧光强度随时间的变化情况。通过对数据的分析得出:与没有经过酸碱滴定的番茄红素-丙酮溶液相比,酸性条件下,荧光强度相对较小,而在碱性条件下,其荧光强度相对较大;pH=1时,番茄红素-丙酮溶液的荧光峰位发生了红移,而pH=11和pH=13时,其荧光峰位又有不同程度的蓝移;在强酸和强碱环境中番茄红素不稳定,其荧光峰强度下降较快,这是因为在强酸环境下重原子效应的影响,和强碱环境下番茄红素参加了阴离子聚合反应;番茄红素在有机溶剂和弱碱环境下比较稳定,其荧光强度下降较慢。 相似文献
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A.M. Tyryshkin S.A. Lyon T. Schenkel J. Bokor J. Chu W. Jantsch F. Schffler J.L. Truitt S.N. Coppersmith M.A. Eriksson 《Physica E: Low-dimensional Systems and Nanostructures》2006,35(2):257
We discuss pulsed electron spin resonance measurements of electrons in Si and determine the spin coherence from the decay of the spin echo signals. Tightly bound donor electrons in isotopically enriched 28Si are found to have exceptionally long spin coherence. Placing the donors near a surface or interface is found to decrease the spin coherence time, but it is still in the range of milliseconds. Unbound two-dimensional electrons have shorter coherence times of a few microseconds, though still long compared to the Zeeman frequency or the typical time to manipulate a spin with microwave pulses. Longer spin coherence is expected in two-dimensional systems patterned into quantum dots, but relatively small dots will be required. Data from dots with a lithographic size of 400 nm do not yet show longer spin coherence. 相似文献
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Phase control of group-velocity-based biexciton coherence in a multiple quantum well nanostructure 下载免费PDF全文
A double cascade-type four-level multiple-quantum-well-based exciton-biexciton transitions are proposed. The study is carried out on a 4.8-rim ZnSe single-quantum well which is embedded into ZnMgSSe cladding layers and pseudomor- phically grown by molecular beam epitaxy on a (0 0 1) GaAs substrate. It is displayed that the exciton spin relaxation and relative phases between applied fields can influence the transient and steady-state behaviors of absorption, dispersion, and group velocity of two weak probe and signal fields. Also, transient behaviors of electron population of different levels are discussed. It is found that the probe or signal amplification occurs in the absence of population inversion. 相似文献
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文章阐明微扰色动力学在π介子虚Compton散射过程中的应用性问题.在此过程中,量子色动力学耦合常数除了端点奇点之外还有中心区域的奇点.于是引进一套简单的技术来判断这些奇点的贡献,并认为这些贡献在一定能标上不妨碍微扰色动力学的应用.提出“工作点”判断法来论证微扰色动力学何时对某个遍举过程是适用的.不同的π介子分布振幅的适用性被详细的考察.得到10 GeV2时微扰量子色动力学开始工作;如果放宽限制,工作点将只有4 GeV2. 相似文献
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采用有机金属化学气相沉积技术在Si(111)衬底上生长蓝光多量子阱发光二极管(LED) 结构, 通过在量子阱下方分别插入两组不同厚度的InGaN/GaN超晶格, 比较了超晶格厚度对LED光电性能的影响. 结果显示: 随超晶格厚度增加, 样品的反向漏电流加剧; 300 K下电致发光仪测得随着电流增加, LED发光光谱峰值的蓝移量随超晶格厚度增加而减少, 但不同超晶格厚度的两个样品在300 K下的电致发光强度几乎无差异. 结合高分辨X射线衍射仪、扫描电子显微镜、透射电子显微镜对样品的位错密度和V形坑特征分析, 明确了两样品反向漏电流产生巨大差异的原因是由于超晶格厚度大的样品具有更大的V形坑和V形坑密度, 而V形坑可作为载流子的优先通道, 使超晶格更厚的样品反向漏电流加剧. 通过对样品非对称(105)面附近的X射线衍射倒易空间图分析, 算得超晶格厚度大的样品其InGaN量子阱在GaN上的弛豫度也大, 即超晶格厚度增加有利于减小InGaN量子阱所受的应力. 综合以上影响LED发光效率的消长因素, 导致两样品最终的发光强度相近. 相似文献
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E.C. Reynhardt L. Latanowicz 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,130(2):195-208
Equations for the temperature dependence of proton and deuteron spin–lattice relaxation rates and second moments due to a complex motion consisting of classical jumps over a potential barrier and quantum mechanical tunneling through the barrier have been derived. Asymmetric double and triple potential wells are considered. These equations have been employed to analyze proton spin–lattice relaxation data for solid naphthazarin in the laboratory and rotating frames as a function of temperature. It is shown that tunneling plays an important role in the proton transfer dynamics of this compound. 相似文献
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The dynamic characteristics of a semiconductor laser with optical feedback are strongly dependent on the injection current and the reflectivity and position of the external feedback reflector. We investigated the relaxation oscillation enhancement and coherence collapse state of the laser oscillation based on the laser rate equations. It is well known that laser output power jumps with increase of the injection current due to external mode transition. But here for the first we time demonstrate the existence of a chaotic scenario within successive laser power jumps. The results calculated by numerical simulations based on the rate equations are compared with those of the experiments and good coincidence between them is found. 相似文献
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Barney L. Bales Miroslav Peric Maria Teresa Lamy-Freund 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,132(2):279-286
A simple expression is derived to compute the total Gaussian linewidth of a Voigt line that is broadened by sinusoidal magnetic-field modulation as follows: ΔHGpp(Hm)2= ΔHGpp(0)2+ κ2H2m, where ΔHGpp(Hm) is the Gaussian linewidth observed with an modulation amplitudeHm/2 and ΔHGpp(0) is the Gaussian linewidth in the limit of zero modulation. The field modulation contributes an additional Gaussian broadening of κHm, where κ is a constant, which adds in quadrature to ΔHGpp(0) to give the total Gaussian linewidth. Denoting the overall linewidth of the Voigt line in the absence of modulation broadening by ΔH0pp(0), it is shown, both by analytical means and by spectral simulation, that the constant κ is equal to 1/2 in the limit ofHm ΔH0pp(0); however, using values ofHmas large as ΔH0pp(0) leads to only minor departures from κ = 1/2. The formulation is valid both for Lorentzian and Voigt lines and is tested for 2,2,5,5-tetramethylpyrrolidin-1-oxyl-3-carboxylic acid (3-carboxy proxyl) in CCl4and in aqueous buffer. This spin probe was studied because the proxyl group is the only major spin-probe moiety whose Gaussian linewidth had not been characterized in the literature. For 3-carboxy proxyl, it is found that ΔHGpp(0) = 1.04 ± 0.01 G independent of solvent polarity. Precision values of the14N hyperfine coupling constant for 3-carboxy proxyl at 9.5°C are as follows: 14.128 ± 0.001 G in CCl4and 16.230 ± 0.002 G in aqueous buffer. The temperature dependence of ΔHGpp(0) and the14N hyperfine coupling constant are reported as empirical equations. Results of the present work taken together with previously published data permits accurate correction for the effects of inhomogeneous broadening due to unresolved hyperfine structure and modulation broadening for the majority of spin probes in common use. 相似文献
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Yoshihiro Ohtsuka 《Optical Review》1995,2(5):347-351
This paper describes invariance of the normalized optical spectrum for a particular class of optical fields propagated in the far zone from a secondary, spatially, partially coherent source. The optical field across the secondary planar source is inhomogeneous to give the complex degree of spectral coherence such that μ = h(αω(ρ1–ρ2))exp(iɛω(ρ12–ρ22)), where α, ɛ are constants, ω is optical frequency, and ρ1, ρ2 denote two points in the secondary source. This expression for μ is the same as obtained in the Fresnel zone from a primary, spatially incoherent source. The invariance law does not hold for the spectrum of the light propagated from the primary source. 相似文献
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methodology for bremsstrahlung (BS) background correction to extract a true Compton profile in high-energy Compton scattering
experiments is presented. The BS background profiles for Hg, computed within the Born approximation, are estimated for different
values of incident energy. It is seen for the first time that the BS background contribution in high-energy Compton profile
experiments like those employing third generation synchrotron radiation sources comes out to be significant and non-linear.
Further, it is found that the incorporation of BS correction in data reduction of such an experiment performed on Hg at 662
keV energy helps in reconciliation of theory and experiment. 相似文献
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光源功率谱对白光干涉测量的影响 总被引:1,自引:0,他引:1
本文从理论上分析了白光干涉测量中光源功率谱宽、包络函数、纵模形状和间隔等与干涉峰宽度、周期间的关系,从而讨论了空间干涉法在保偏光纤参数测量和传感应用中光源功率谱参数对测量分辨率、动态范围等的影响。 相似文献