共查询到13条相似文献,搜索用时 0 毫秒
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研究了脉冲激发下单个半导体量子点中单光子发射的统计特性.在旋转波近似条件下,由系统粒子数演化主方程并结合量子回归理论推导了二阶相关函数的运动方程,利用此方程讨论了二阶相关函数随输入脉冲面积的关系.在窄脉冲宽度的脉冲激发下,单光子的发射概率p和效率η都随着强度的增强而产生振荡.研究表明,采用窄脉冲宽度,当输入脉冲面积在π附近时可以得到较高的单光子发射效率.
关键词:
半导体量子点
单光子发射
三能级系统 相似文献
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Zhang FaQing Li ZhengHong Yang JianLun Ye Fan Wang Zhen Xia GuangXin Ying ChunTong Liu GuangJun 《中国科学G辑(英文版)》2007,50(6):698-706
For a scintillating-fiber array fast-neutron radiography system, a point-spread- function computing model was introduced, and the simulation code was developed. The results of calculation show that fast-neutron radiographs vary with the size of fast neutron sources, the size of fiber cross-section and the imaging geometry. The results suggest that the following qualifications are helpful for a good point spread function: The cross-section of scintillating fibers not greater than 200μm×200μm, the size of neutron source as small as a few millimeters, the distance between the source and the scintillating fiber array greater than 1 m, and inspected samples placed as close as possible to the array. The results give suggestions not only to experiment considerations but also to the estimation of spatial resolution for a specific system. 相似文献
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用最近发展的产生函数(Generating Function)方法,研究了在连续激光场和射频场作用下存在固有偶极矩的 型三能级单分子体系发射光子的统计性质。主要讨论了不同激光场强度和不同射频场,激光场失谐频率对系统平均发射光子数 ,线型 和Mandel 参数的影响,以及射频场对系统发射光子等待时间分布 的影响等。结果表明:外加激光场和射频场对单分子发射光子都具有很好的调控作用,可以选择合适的激光场参数和射频场参数来操纵单分子发射光子。 相似文献
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An effective scatter correction method based on single scatter simulation for a 3D whole-body PET scanner 下载免费PDF全文
Hamamatsu SHR74000 is a newly designed full three-dimensional (3D) whole body
positron emission tomography (PET)
scanner with small crystal size and large field of view (FOV). With
the improvement of sensitivity, the scatter events increase
significantly at the same time, especially for large objects.
Monte Carlo simulations help us to understand the scatter phenomena and
provide good references for scatter correction. In this paper, we
introduce an effective scatter correction method based on single
scatter simulation for the new PET scanner, which accounts for the
full 3D scatter correction. With the results from Monte Carlo
simulations, we implement a new scale method with special
concentration on scatter events from outside the axial FOV and
multiple scatter events. The effects of scatter correction are
investigated and evaluated by phantom experiments; the results
show good improvements in quantitative accuracy and
contrast of the images, even for large objects. 相似文献
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为满足某地面实验中视觉测量系统的研制需求,研究了一种基于单幅图像的大尺寸实际平面上光点的定位方法。通过建立关于实际平面上光点3D坐标的数学模型,结合利用图像确定的通过光点的空间光束,实现了由单幅图像确定光点的3D坐标。依据具体特点,把实际平面分为高阶曲面型、分块平面型和分块曲面型3种类型,并分别给出了相应类型的光点定位方法。仿真实验验证了所提出方法的正确性,并比较分析了方法的精确性;实际试验数据表明,所提出方法可以满足尺寸为8000mm×8000mm的大型实际平面上光点的定位需求,定位误差小于1mm。 相似文献
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Hidekazu Takano Shigeki Konishi Takahisa Koyama Yoshiyuki Tsusaka Satoshi Ichimaru Tadayuki Ohchi Hisataka Takenaka Yasushi Kagoshima 《Journal of synchrotron radiation》2014,21(2):446-448
The experimental procedure for obtaining the point spread function (PSF) of a focusing beam generated using an X‐ray multilayer zone plate (MZP) with a narrow annular aperture has been developed. It was possible to reconstruct the PSF by applying the tomographic process to the measured dataset consisting of line spread functions (LSFs) in every radial direction on the focal plane. The LSFs were measured by a knife‐edge scanning method of detecting scattered intensity. In the experimental work, quasi‐monochromatic undulator radiation with a first harmonic energy of 20 keV was directly focused without a monochromator by the MZP, and the PSF was measured using this procedure. As a result, a near diffraction‐limited focused beam size of 46 nm full width at half‐maximum was obtained. 相似文献
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Derivation of two point spread functions PSFs suitable for infrared thermograms analysis is illustrated, based on two unique approaches, one based on depth decaying limit and one on diffusion limit. Experimental work using PMMA sample with back drilled holes and pulsed thermographic routine is utilized to show the effectiveness of deconvoluting pixel temperature transient history with suggested PSF’s. Synthetic second time derivative thermograms are utilized for comparison and the signal to noise ratio is used as a figure of merit for quantification. 相似文献
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Generation of countless embedded trumpet-shaped chaotic attractors in two opposite directions from a new three-dimensional system with no equilibrium point 下载免费PDF全文
A new three-dimensional(3D) continuous autonomous system with one parameter and three quadratic terms is presented firstly in this paper. Countless embedded trumpet-shaped chaotic attractors in two opposite directions are generated from the system as time goes on. The basic dynamical behaviors of the strange chaotic system are investigated. Another more complex 3D system with the same capability of generating countless embedded trumpet-shaped chaotic attractors is also put forward. 相似文献
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A novel methodology for constructing a multi-wing chaotic and hyperchaotic system with a unified step function switching control 下载免费PDF全文
This paper aims at developing a novel method of constructing a class of multi-wing chaotic and hyperchaotic system by introducing a unified step function. In order to overcome the essential difficulties in iteratively adjusting multiple parameters of conventional multi-parameter control, this paper introduces a unified step function controlled by a single parameter for constructing various multi-wing chaotic and hyperchaotic systems. In particular, to the best of the authors' knowledge, this is also the first time to find a non-equilibrium multi-wing hyperchaotic system by means of the unified step function control. According to the heteroclinic loop Shilnikov theorem, some properties for multi-wing attractors and its chaos mechanism are further discussed and analyzed. A circuit for multi-wing systems is designed and implemented for demonstration, which verifies the effectiveness of the proposed approach. 相似文献