共查询到20条相似文献,搜索用时 46 毫秒
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基于一维分子晶体系统的 Holstein 模型,采用压缩-相干态展开方法,计及电子-声子间量子关联和重整化平移修正,分析和研究电子-双声子相互作用对极化子-孤子系统基态性质和量子涨落的影响.推导了一维极化子-孤子系统的封闭形式非线性方程.应用非线性项展开方法,给出非线性方程的解析解和相关基态特性结果.研究表明,仅当电子-双声子耦合强度 g1<0时非线性方程才有孤波解,此时声子量子涨落效应随着压缩的增加,极化子-孤子系统基态能量变得更负,孤子局域减少,孤子态更加稳定;另一方面,电子密度涨落〈Δ2n〉和声子坐标-动量的不确定量〈Δ2p〉〈Δ2q〉比无声子压缩效应的大,极化子结合能变得更负.特别是,当g1<0时,双声子效应的量子涨落〈Δ2n〉与〈Δ2p〉〈Δ2q〉的值比单声子情况有明显增加.
关键词:
压缩-相干态展开
极化子-孤子态与量子涨落
电子-双声子相互作用
非线性薛定谔方程 相似文献
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对像散椭圆高斯光束, 传统的M2因子测量采用Mx2和My2来描述光束质量. 当光束绕z轴旋转, Mx2和My2会随之变化, 单纯采用Mx2和My2来评价激光光束质量并不唯一. 为此采用了像散椭圆高斯光束的M2因子矩阵, 理论推导出了在同一坐标系下光场绕z轴旋转不同角度后的M2因子矩阵, 找出了光场旋转前后的M2因子矩阵元的不变量关系. 数值模拟、 实验测量得到M2因子矩阵主对角元随光斑旋转角度的变化轨迹曲线, 及反对角元随旋转角度的变化规律. 理论推导与实验结果相符. 结果表明, 像散椭圆高斯光束在主方向上时Mx2与My2之和最小; 在其他方向上的Mx2, My2之和大于在主方向上的Mx2, My2之和; 反对角元随旋转角度呈周期变化, 在主方向上为零.
关键词:
M2因子矩阵')" href="#">M2因子矩阵
像散椭圆高斯光束
实验测量
矩阵光学 相似文献
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本文研究了不同能量(5—600keV)和不同剂量(1014-1016atom/cm2)下的P2+和P+注入〈100〉单晶硅后的损伤及退火行为。实验结果表明,P2+注入所产生的损伤总是大于P+注入所产生的损伤。由移位效率之比ND*(mol)/2ND*(atom)所表征的分子效应随入射能量的改变而变化并在100keV(P2+),50keV(P+)处达到极大值。P2+与P+注入的样品,退火后的载流子分布也有某些区别。我们认为,产生这些分子效应的基本原因是位移尖峰效应,但当入射离子的能量较高时,还应该考虑离子、靶原子之间的多体碰撞效应的贡献。
关键词: 相似文献
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在中国南部热带海域,基于超声风速仪阵列测量的大气三维风速可计算得到速度结构常数Cv2,结合折射率梯度可计算得到折射率结构常数Cn2,其中温度和湿度对Cn2的影响是通过折射率梯度体现。将超声单点虚温估算方法的计算结果作为标定,与本研究的超声风速仪阵列估算方法的144次计算结果进行相关性分析,得到平均相关系数为0.85,最高可达0.99,最低为0.71;通过误差分析,可得平均|Δlg Cn2|为0.3。研究表明:超声风速仪阵列能够捕捉高频光学湍流效应的变化情况,利用超声风速仪阵列估算近海面光学湍流强度可以从风速、湿度、温度等不同方面分析湍流效应,实现在无人值守情况下对光学湍流的连续、长期的全天候观测。 相似文献
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本文从广义协变的运动方程和麦克斯韦方程出发,导出了电子等离子体波各量的解析表达式。指出△ω=2ωp的等离子体波是完全简谐的。完全共振的条件由△ω=2ω(p0)[1+(e2(A2((1)2)+(A2((2)2))/(2m2c4)+(3e2A2(1)A2(2))/(m2c4)]-1/2 给出。
关键词: 相似文献
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在八个(111)面磁泡膜上,观察了施加面内(in-plane)磁场后在不同晶轴方向上条状畴的消失过程,测量了条畴消失场Hs*和磁畴消失场Hk*与面内磁场的方向的关系。本文计及立方磁晶各向异性,完善了面内磁场中条畴的稳定性理论。用该理论定性地解释了实验结果的主要特点。导出了Hs*与立方各向异性及面内场方向的两种近似的理论关系,它们分别适用于面内场方向靠近和不十分靠近〈110〉晶轴的情形。它们和实验结果是大致符合的。在〈110〉晶轴上,理论关系具有下列简单的形式:Hk*<110>=Hs*<110>=Hk{1+(k1/2Ku)-[al/h(4πMs/Hk)2]2/3},此式与实验结果符合得相当好。
关键词: 相似文献
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利用非波恩-奥本海默近似的三维含时量子波包法,理论研究了氢分子离子在强激光场中的解离动力学.通过分析H2+在不同的初始振动态(ν=0–9)和激光场强度下的解离核动能谱,得到了H2+的光解离机理及其随激光场的变化规律.研究结果表明:当激光场的强度I1=5.0×1013 W/cm2时,分子的解离来源于高振动态ν=5–9,其解离机理主要是通过键软化、键硬化和阈下解离过程.当激光场的强度I2=1.0×1014 W/cm2 时,H2+在低振动态ν=3–4上的阈上解离起主导作用,而高振动态的键软化、键硬化和阈下解离所占的比重明显地下降了.研究结果为后续的量子调控的实验研究提供了科学的理论预测和指导.
关键词:
光解离
氢分子离子
含时波包法
核动能谱 相似文献
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In classical physics a beam of light propagates in a perfectly straight line and this means that we can measure small displacements with unlimited accuracy. However, this is not correct for real laser beams when we take the quantum properties of light into account. Spatial measurements will be limited by quantum noise, similar to the limitations for optical communication and sensing. Here we derive the spatial quantum noise limit and show how to measure it. Next we demonstrate that we can use specially prepared light with quantum correlations, so-called squeezed light, to improve spatial measurements to below this quantum limit. In this way we prepare a beam which goes in a straighter line than the output of any conventional laser. 相似文献
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Measurement slight amounts of absorption of light with accuracy beyond the standard quantum limit has been experimentally demonstrated. The quantum-correlated twin beams used in the measurement were generated from a nondegenerate optical parametric oscillator including an alpha-cut KTiOPO(4) crystal pumped by an intracavity frequency-doubled Nd:YAG laser. The noise in the intensity difference between the twin beams was reduced by 88% below the standard quantum limit (SQL). The signal-to-noise ratio was improved by 7 dB with respect to the SQL of the total light employed in the experiment and by 4 dB with respect to that of the signal light. 相似文献
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Gh. Solookinejad M. Panahi E. Ahmadi Sangachin Seyyed Hossein Asadpour 《Chinese Journal of Physics (Taipei)》2017,55(1):96-104
In this letter, phase control of the Goos-Hänchen shifts of the reflected and transmitted probe light beams through a cavity containing four-level InGaN/GaN quantum dot nanostructure is theoretically discussed. In order to achieve the wave functions and their corresponding energy levels of the mentioned quantum dot nanostructure, Schrödinger and Poisson equations must be solved in a self consistent manner for carriers (here electron) in quantum dot. It is found that the coupling field, the pumping field as well as the cycling field can enhance the GH shifts of the reflected and transmitted probe beams. The effect of relative phase and the detuning of the probe light on the GH shifts of the reflected and transmitted probe beams are also investigated. We find that the GH shifts can be switched between the large positive and negative values by adjusting the controllable parameters. 相似文献
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E. Giacobino C. Fabre A. Heidmann R. Horowicz S. Reynaud D. Grandclément G. Grynberg M. Pinard 《Hyperfine Interactions》1987,37(1-4):109-124
It is shown that oscillators using nearly degenerate parametric conversion or four-wave mixing in the phase conjugation geometry
generate pairs of highly correlated photons. The intensity difference of the two corresponding light beams is then expected
to be below the shot noise limit. This property can be used to produce intensity stabilized light beams below the quantum
limit.
The phases of the twin beams also exhibit interesting correlation properties which will be discussed. Moreover, the combination
of the twin beams gives a squeezed state, which has been observed by other authors when the device is below the oscillation
threshold. We will describe preliminary results of experiments performedabove oscillation threshold. 相似文献
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利用谐振倍频产生纠缠光束 总被引:6,自引:2,他引:4
根据Anderson等近期的理论研究,简要介绍了Ⅱ类相位匹配倍频过程产生纠缠光的理论计算过程,得出了纠缠的类型、纠缠度与抽运功率的函数关系和纠缠度的理论值。利用Ⅱ类非临界相位匹配的KTP晶体作为倍频晶体,采用倍频腔结构为半整块的单端驻波腔(由于腔的入射光与反射光重合,无法直接取出纠缠光束,需要先将腔内的纠缠光束当作一对压缩的耦合模取出,再在50/50光学分束器上干涉恢复一对纠缠的本征模),在基频光波长获得了具有正交振幅负关联、正交相位正关联特征的量子纠缠光束对,它们的正交振幅和噪声低于散粒噪声基准0.2±0.1 dB,正交相位差噪声低于散粒噪声基准1±0.2 dB。最后分析了两个正交分量的纠缠度不平衡的原因。与目前常用的光学参变振荡器相比,此类纠缠产生源的装置具有便捷和结构简单的优点。 相似文献
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Yun Zhang 《Optics Communications》2006,266(2):598-603
A conditional quantum correlation transfer is demonstrated experimentally for continuous variables by employing two pairs of twin-beams states. In present paper, the quantum correlation of twin beams is indicated by loss coefficient or “gemellity”, which is the remaining noise on the intensity difference normalized to the shot noise level. The quantum correlation between two initial idler beams with loss coefficient of 0.4 was conditionally transferred from two pairs of initially independent twin beams with loss coefficient of 0.2. A theory of conditional quantum correlation transfer and comparison between experimental results and theoretical prediction are also presented. The experimental results agree with the theory well. 相似文献
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H.A. Bachor 《Applied physics. B, Lasers and optics》2005,80(7):889-896
The quantum properties of light play an ever increasing role in optics. Thanks to the ability to generate and use special
light with modified quantum noise and to the generation of optical entanglement, we can now avoid the conventional limits
imposed by the shot noise. In addition, we can create new quantum information protocols. This article concentrates on the
case of continuous laser beams, which are used in many precision measurements and applications. The article summarizes some
of the concepts, reviews the technical development, provides a simple and reliable model and shows some of the current directions
of using optical quantum correlations, such as for the storage of quantum information.
PACS 42.50.Dv 相似文献
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We have experimentally demonstrated how two beams of light separated by an octave in frequency can become entangled after their interaction in a chi;{(2)} nonlinear medium. The entangler was a nonlinear optical resonator that was strongly driven by coherent light at the fundamental and second-harmonic wavelengths. An interconversion between the fields created quantum correlations in the amplitude and phase quadratures, which were measured by two independent homodyne detectors. Analysis of the resulting correlation matrix revealed a wave function inseparability of 0.74(1)<1, thereby satisfying the criterion of entanglement. 相似文献
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We report the first direct experimental characterization of continuous variable quantum Stokes parameters. We generate a continuous wave light beam with more than 3 dB of simultaneous squeezing in three of the four Stokes parameters. The polarization squeezed beam is produced by mixing two quadrature squeezed beams on a polarizing beam splitter. Depending on the squeezed quadrature of these two beams the quantum uncertainty volume on the Poincaré sphere becomes a "cigarlike" or "pancakelike" ellipsoid. 相似文献