量子关联成像及其雷达应用研究

介绍了量子关联成像的物理原理,阐述了量子关联成像灵敏度高、抗干扰能力强、信息获取效率高、能够实现单像素探测成像和无透镜成像的技术特点;探讨了量子关联成像雷达的运动物体成像问题和大气影响应对问题,指出可通过提高采样频率、升级跟踪手段、优化成像策略等方式提升量子关联成像雷达的应用性能;展望了量子关联成像雷达在侦察、预警等领域的发展方向,提出未来通过发展极弱光条件下的成像技术、优化设计照明方式、建立多基站协同体系、发展人工智能算法和多维信息智能融合算法等方式,进一步提升量子关联成像雷达的发现概率、跟踪精度、判别准确度、有效作用距离。     

太赫兹波计算鬼成像:原理和展望

本文立足于太赫兹波成像领域近年来备受关注的研究热点—太赫兹波计算鬼成像,首先回顾了鬼成像从量子到经典再到计算的历史过程,然后阐述了计算鬼成像的数学原理,随后综述了计算鬼成像在太赫兹波段的发展历程,及其在超衍射分辨成像、石墨烯光电导成像、太赫兹光谱成像等方面的应用,并在最后展望了太赫兹波计算鬼成像的发展前景:计算鬼成像作为一种成像手段,可以绕开在太赫兹频段缺乏经济高效的焦面阵列式探测器的难题,但目前的成像帧率还难以满足快速成像的应用需求,相信在未来随着器件性能的提升和成像算法的优化,其成像帧率可以得到大幅提升。     

18.2nm正入射显微成像系统滤光片的研究

18．2nm正人射显微成像系统用多层膜可极大地提高18．2nm的反射率，但它对紫外、可见和红外光也产生很高的反射。显微成像系统用的激光等离子体光源会在红外到敦X射线产生大量的辐射，18．2nm正入射显微系统用的胶片对所有光谱都十分敏感。因此，182nm正人射显微成像系统需要用滤光片滤除不需要的光辐射并对18．2nm的软X射线有较大的透射比，这样才能获得18．2nm的软X射线像。本文讨论了18．2nm正入射显微成像系统用滤光片的设计、制作及其特性。为了去除滤光片膜中的应力，用交替蒸镀Al和C多层膜的方法来制备法光片，铝和碳膜是用磁控溅射法制备的。针孔透过率和成像实验表明，所制备的滤光片满足了18．2nm正入射显微成像系统对滤光片的要求，并且为进一步制备其他薄膜滤光片打下了基础。     

生物分子吸附膜层的图像显示——光学椭偏显微成像技术应用之一

本文采用以扩展平行光为光源的椭偏显微成像技术以图像形式显示吸附于固体表面上的蛋白单分子膜层的几何厚度分布。此测量技术为表面检测和超薄膜研究提供了手段。．     

环形LED多波段光源成像系统的研制及应用

目的：研究显现、提取现场潜在物证的新设备及其应用。方法：研制环形LED多波段光源;以该光源为基础,集成红紫外相机、载物台等设备组成相关的成像系统;研究该系统在显现、提取现场潜在物证方面的应用。结果：成功研制出环形LED多波段光源成像系统;该系统在实际案件中得到了成功应用。结论：环形LED多波段光源成像系统为显现、提取现场潜在物证提供了一种新设备,该设备集成了多波段光源和成像系统,提高了对现场潜在物证的提取能力。     

基于显微光学成像的微细纤维测量识别系统光源优化研究

显微光学成像的纤维识别系统的照明光源,对成像质量有很大影响。由于单个LED光源发光功率有限,且在照射面的光分布不均,导致系统采集到的微纳米级纤维(单丝平均直径15～40μm)图像模糊,影响测量与识别结果的准确性。根据LED的光学特性,对系统的照明光源进行优化设计,设计了3种不同的LED平面光源阵列,并根据LED阵列光源在照射面上的照度表达式,仿真模拟给出LED阵列的照度分布,并以实验进行验证,对系统实际检测的图像进行图像识别处理和图像参数峰值信噪比评价,给出优化结果。研究结果表明,优化后的LED平面光源阵列有效地解决了照度不均导致的微细纤维图像模糊识别不清的问题,优化后得到的纤维样品图像边缘清晰,有效提高了系统检测纤维样品的图像质量,为微细纤维测量识别与研究提供了新的途径。     

相干光对共聚焦显微镜轴向强度响应的影响

在共聚焦显微镜中,光源和探测器是有限大小的,成像过程是部分相干的,有必要分析光源对系统分辨能力的影响。首次利用部分相干成像理论分析了共聚焦显微镜成像过程,得到在相干光是点光源、均匀光源和高斯光源的情况下系统轴向光强。给出模拟结果,发现当光源和探测器都小于会聚透镜的艾利斑,且它在样品空间的数值孔径增大时,系统轴向分辨能力会提高且不受光源大小及光强分布的影响。     

中国科大等实现最高效量子态层析测量

正近日,中科院院士、中国科学技术大学教授郭光灿团队与复旦大学、北京理工大学、南京邮电大学研究者合作,提出基于光子量子行走的确定性集体测量方法,实现了目前国际上最高效的量子态层析测量。相关成果在线发表于《自然—通讯》。探索量子测量能力和局限性对许多量子物理基本问题及量子计量、量子成像、引力波探测等应用具有重要意义。研究发现,虽然这些相同量子系统之间没有纠缠,甚至没有经典关联,但是对他们进行集体测量却比现有的对每份量子系统单独测量能提取更多的信息,从而更高效、更精确地完     

量子点在细胞以及体内生物中成像的研究进展

量子点是一种荧光半导体纳米材料,与生物分子结合成一种高亮度而稳定的荧光探针应用于生物成像。通过生物成像可观察量子点标记分子与其靶标的相互作用,实时观测其在活细胞及活体中的运行轨迹,实现对细胞水平及在活体层次的研究。利用这种生物成像技术还可以研究疾病的发生发展过程。介绍了量子点的光学特性,重点综述了量子点在细胞、体内生物成像中的应用,并展望了其发展前景。     

基于QR码的多图像关联成像算法光学加密机理研究

目的研究解决多图像的关联成像加密问题。方法采用双重QR编码处理,将多图像的关联成像加密问题转变为单个QR码图像的关联成像问题。结果 QR码作为关联成像的成像物体,能在远低于传统关联成像采样率的条件下重构出清晰的图像,实现信息的高质量恢复。结论在保证图像质量的情况下,该算法的安全性较高,能有效抵抗一定的噪声攻击和统计分析攻击,并极大地减少了加密系统对多图像的加密成本。     

Quantum noise analysis in correlated two-photon imaging

The theoretical analysis of quantum noise is presented in a correlated two-photon imaging system with entangled photons. The noise is strongly influenced by the size and the entanglement degree of the source. An increase of the source size results in a remarkable decrease of the amplitude of the noise when the size is much smaller than the aperture of the lens, whereas the change will not be obvious if the size is close to the aperture. The difference of the effects from the source between correlated imaging formed with entangled photons and with partially coherent light is also discussed.     

Two-photon interferometry for high-resolution imaging

This paper discusses the advantages of using non-classical states of light for two aspects of optical imaging: the creation of microscopic images on photosensitive substrates, which constitutes the foundation for optical lithography, and the imaging of microscopic objects. In both cases, the classical resolution limit given by the Rayleigh criterion is approximately half of the optical wavelength. It has been shown, however, that by using multi-photon quantum states of the light field, and a multi-photon sensitive material or detector, this limit can be surpassed. A rigorous quantum mechanical treatment of this problem is given, some particularly widespread misconceptions are addressed, and turning quantum imaging into a practical technology is discussed.     

Quantum theory for 1D X-ray free electron laser

Abstract

Classical 1D X-ray Free Electron Laser (X-ray FEL) theory has stood the test of time by guiding FEL design and development prior to any full-scale analysis. Future X-ray FELs and inverse-Compton sources, where photon recoil approaches an electron energy spread value, push the classical theory to its limits of applicability. After substantial efforts by the community to find what those limits are, there is no universally agreed upon quantum approach to design and development of future X-ray sources. We offer a new approach to formulate the quantum theory for 1D X-ray FELs that has an obvious connection to the classical theory, which allows for immediate transfer of knowledge between the two regimes. We exploit this connection in order to draw quantum mechanical conclusions about the quantum nature of electrons and generated radiation in terms of FEL variables.     

High-stability time-domain balanced homodyne detector for ultrafast optical pulse applications

Abstract

Low-noise, efficient, phase-sensitive time-domain optical detection is essential for foundational tests of quantum physics based on optical quantum states and the realization of numerous applications ranging from quantum key distribution to coherent classical telecommunications. Stability, bandwidth, efficiency, and signal-to-noise ratio are crucial performance parameters for effective detector operation. Here we present a high-bandwidth, low-noise, ultra-stable time-domain coherent measurement scheme based on balanced homodyne detection ideally suited to characterization of quantum and classical light fields in well-defined ultrashort optical pulse modes.     

Green-emissive carbon quantum dots with high fluorescence quantum yield: Preparation and cell imaging

High fluorescence quantum yield (QY), excellent fluorescence stability, and low toxicity are essential for a good cellular imaging fluorescent probe. Green-emissive carbon quantum dots (CQDs) with many advantages, such as unique fluorescence properties, anti-photobleaching, low toxicity, fine biocompatibility and high penetration depth in tissues, have been considered as a potential candidate in cell imaging fluorescent probes. Herein, N, S-codoped green-emissive CQDs (QY= 64.03%) were synthesized by the one-step hydrothermal method, with m-phenylenediamine as the carbon and nitrogen source, and L-cysteine as the nitrogen and sulfur dopant, under the optimum condition of 200 °C reaction for 2 h. Their luminescence was found to originate from the surface state. In light of the satisfactory photobleaching resistance and the low cytotoxicity, CQDs were used as a cell imaging probe for HeLa cell imaging. The results clearly indicate that cells can be labeled with CQDs, which can not only enter the cytoplasm, but also enter the nucleus through the nuclear pore, showing their broad application prospect in the field of cell imaging.     

Towards time-efficient ghost imaging

Reducing the time necessary to acquire information is highly desirable in almost every context. Ghost imaging is no exception, which is very time consuming due to its scanning nature and low light levels innate to quantum experiments. This work aimed to reduce the time required to reconstruct the image whilst maintaining quality. In doing so, we followed two complementary approaches: one varying the experimental parameters, and another implementing computational processing. We defined a performance measure based on the image reconstruction time and its resemblance to the original object, and determined that the use of image processing and recognition algorithms offers major improvements in temporal efficiency. Importantly, if the main purpose of imaging is solely object recognition, low resolution mask patterns give better results, whereas higher resolution patterns yield better resolved images, at the expense of time. We believe this work will pique interest in the ghost and single-pixel imaging communities.     

Cloaking and illusion of quantum imaging with entangled photon pairs

Quantum ghost imaging is a nonlocal imaging technique in which the image or diffraction pattern of an object illuminated by photon pairs can be observed through the correlation measurement. This study theoretically demonstrates the cloaking effect of such a quantum imaging. Quantum ghost imaging completely offsets two objects that are placed at proper positions in the interferometer. Furthermore, illusion of quantum imaging, where an object transforms into another object, has also been observed. This phenomenon can be understood by quantum interferences in the correlation measurement.     

Decay of two-qubit correlation in correlated stochastic dephasing

Time evolutions of quantum correlation, classical correlation and total correlation of two qubits are investigated when the two qubits are placed under the influence of classical phase fluctuations with correlation. Stochastic variables that describe the phase fluctuations are correlated and subject to the stationary Gauss–Markov process. The model includes the local and global dephasing models. It is shown that the quantum correlation measured by the quantum discord is increased by the correlation between the stochastic variables in the initial time region while the classical correlation and the total correlation are not. Furthermore the entanglement, the optimal fidelity of the quantum teleportation and the violation of the Bell inequality are investigated.