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Two-dimensional characterization of three-dimensional magnetic bubbles in Fe3Sn2 nanostructures

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National Science Review 2021年第6期8卷 188-194页

作者： Jin Tang Yaodong Wu Lingyao Kong Weiwei Wang Yutao Chen Yihao Wang Y.Soh Yimin Xiong Mingliang Tian Haifeng Du anhui province key laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory of the Chinese Academy of Sciencesand University of Science and Technology of China Universities Joint key laboratory of Photoelectric detection Science and technology in anhui province Hefei Normal University School of Physics and Materials Science Anhui University Institute of Physical Science and Information technology Anhui University Paul Scherrer Institute

We report differential phase contrast scanning transmission electron microscopy(TEM) of nanoscale magnetic objects in Kagome ferromagnet Fe3 Sn2 nanostructures. This technique can directly detect the deflection angle of a focused electron beam, thus allowing clear identification of the real magnetic structures of two magnetic objects including three-ring and complex arch-shaped vortices in Fe3 Sn2 by Lorentz-TEM imaging. Numerical calculations based on real material-specific parameters well reproduced the experimental results, showing that the magnetic objects can be attributed to integral magnetizations of two types of complex three-dimensional(3 D) magnetic bubbles with depth-modulated spin twisting. Magnetic configurations obtained using the high-resolution TEM are generally considered as two-dimensional(2 D)magnetic objects previously. Our results imply the importance of the integral magnetizations of underestimated 3 D magnetic structures in 2 D TEM magnetic characterizations.

关键词： skyrmion skyrmion bubbles three-dimensional magnetic structures differential phase contrast scanning transmission electron microscopy micromagnetics

A Sparsity Adaptive Greedy Iterative Algorithm for Compressed Sensing

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A Sparsity Adaptive Greedy Iterative Algorithm for Compresse...

Super-sensitive detection of quantum interferometer in atmospheric environment

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作者： Li Wang Lina Xun Dexiang Zhang Yi Xia College of Electrical Engineering and Automation Anhui University key laboratory of polarization imaging detection technology in anhui province

Aiming at the problem of signal reconstruction with unknown sparsity in compressed sensing, an improved iterative greedy algorithm is proposed to signal reconstruction from low sampling rate. Firstly, a sparsity estimation strategy is used to estimate the sparsity and the true support set of target signal, and then the residual is initialized with the estimated value. In order to optimize the estimated value, it is necessary to determine the direction of the iteration before the iteration begins. The proposed algorithm is associated with the ideas of adaptive, backtracking and greedy choice to iteratively refine. The simulation results show that the proposed algorithm performs better than that of OMP, CoSaMP and SAMP algorithms for both one-dimensional signal and two-dimensional image signal, and the algorithm has better practical application value.

关键词： Compressed sensing sparsity estimation reconstruction algorithm

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Science China(Information Sciences) 2017年第3期60卷 195-201页

作者： Yihua HU Shilong XU State key laboratory of Pulsed Power Laser Electronic Engineering Institute key laboratory of Electronic Restriction of anhui province

With squeezed states or entangled states being the source, quantum metrology, imaging and sensing can break the standard quantum limit(SQL), even reach the Heisenberg limit(HL), which is difficult to achieve by traditional methods. However, the photon loss or phase fluctuation caused by the atmospheric attenuation and turbulence cannot be ignored in the actual application. Atmospheric transmittance and phase fluctuation are related to the detection distance, and the phase sensitivity becomes worse as the distance increases. As the functions of distance, the photon loss and phase fluctuation are uniformly expressed according to the introduction of atmospheric attenuation coefficient, turbulence structure constant and receive aperture size in this *** density matrixes and phase sensitivities of N00 N states and M&M′ states in the atmospheric environment are proposed in terms of distance variables. Then the quantitative computation of super-sensitive distance is carried out. SQL-contour is proposed to describe the super-sensitive ability of the quantum interferometer for the affection from both photon loss and phase fluctuation. The simulation results show that, in atmospheric environment the super-sensitive distance can reach hundreds of meters. M&M′ states with less total photon number are more likely to reflect the advantage of super-sensitivity. SQL-contour can provide references for interferometric source choosing.

关键词： quantum interferometer standard quantum limit entangled states phase sensitivity atmospheric transmission

Efficient single-pixel imaging encrypted transmission based on 3D Arnold transformation

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Chinese Physics B 2024年第3期33卷 378-386页

作者：梁振宇王朝瑾王阳阳高皓琪朱东涛许颢砾杨星 State key laboratory of Pulsed Power Laser technology National University of Defense TechnologyHefei 230001China Advanced Laser technology laboratory of anhui province Hefei 230001China

Single-pixel imaging(SPI)can transform 2D or 3D image data into 1D light signals,which offers promising prospects for image compression and ***,during data communication these light signals in public channels will easily draw the attention of ***,we introduce an efficient encryption method for SPI data transmission that uses the 3D Arnold transformation to directly disrupt 1D single-pixel light signals and utilizes the elliptic curve encryption algorithm for key *** encryption scheme immediately employs Hadamard patterns to illuminate the scene and then utilizes the 3D Arnold transformation to permutate the 1D light signal of single-pixel *** the transformation parameters serve as the secret key,while the security of key exchange is guaranteed by an elliptic curve-based key exchange *** with existing encryption schemes,both computer simulations and optical experiments have been conducted to demonstrate that the proposed technique not only enhances the security of encryption but also eliminates the need for complicated pattern scrambling ***,this approach solves the problem of secure key transmission,thus ensuring the security of information and the quality of the decrypted images.

关键词： single-pixel imaging 3D Arnold transformation elliptic curve encryption image encryption

Molecular exchange and passivation at interface afford high-performing perovskite solar cells with efficiency over 24%

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Journal of Energy Chemistry 2023年第7期82卷 219-227,I0005页

作者： Jianjun Sun Wangchao Chen Yingke Ren Yunjuan Niu Zhiqian Yang Li'e Mo Yang Huang Zhaoqian Li Hong Zhang Linhua Hu key laboratory of Photovoltaic and Energy Conservation Materials Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031AnhuiChina School of Chemistry and Chemical Engineering Anhui Province Key Laboratory of Advanced Catalytic Materials and Reaction EngineeringHefei University of TechnologyHefei 230009AnhuiChina College of Science Hebei University of Science and TechnologyShijiazhuang 050018HebeiChina Hebei Computational Optical imaging and Photoelectric detection technology Innovation Center Hebei International Joint Research Center for Computational Optical Imaging and Intelligent SensingSchool of Mathematics and Physics Science and EngineeringHebei University of EngineeringHandan 056038HebeiChina University of Science and technology of Chin1 Anhui 230026HefeiChina

The interface is crucial for perovskite solar cells(PSCs).However,voids at interfaces induced by the trapped hygroscopic dimethyl sulfoxide(DMSO)can reduce charge extraction and accelerate the film degradation,seriously damaging the efficiency and *** this work,4,4’-dinonyl-2,2’-dipyridine(DN-DP),a Lewis base with long alkyl chains is introduced to solve this *** calculated and experimental results confirm that the dipyridyl group on DN-DP can more strongly coordinate with Pb^(2+)than that of the S=O group on *** strong coordination effect plays a crucial role in removing the DMSO-based adduct and reducing the formation of *** to the electron-donating properties of pyridine,the existence of DN-DP in the perovskite film can passivate the defects and optimize the energy level alignment of the perovskite *** open-circuit voltage(VOC)of the DN-DP-based PSC is improved from 1.107 V(control device)to 1.153 V,giving rise to a power conversion efficiency(PCE)of24.02%.Furthermore,benefiting from the moisture resistance stemming from the hydrophobic nonyl group,the PCE retains 90.4%of the initial performance after 1000 h of storage in the ambient condition.

关键词： Perovskite solar cell Anti-solvent 4 4′-Dinonyl-2 2′-dipyridine Optimized interfaceStability

Study on polarized optical flow algorithm for imaging bionic polarization navigation micro sensor

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Optoelectronics Letters 2018年第3期14卷 220-225页

作者： GUAN Le LlU Sheng LI Shi-qi LIN Wei ZHAI Li-yuan and CHU Jin-kui. key laboratory for Precision and Nona Traditional Machining Technology of Ministry of Education Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of Technology

At present,both the point source and the imaging polarization navigation devices only can output the angle information,which means that the velocity information of the carrier cannot be extracted from the polarization field pattern *** flow is an image-based method for calculating the velocity of pixel point movement in an ***,for ordinary optical flow,the difference in pixel value as well as the calculation accuracy can be reduced in weak *** imaging technology has the ability to improve both the detection accuracy and the recognition probability of the target because it can acquire the extra polarization multi-dimensional information of target radiation or *** this paper,combining the polarization imaging technique with the traditional optical flow algorithm,a polarization optical flow algorithm is proposed,and it is verified that the polarized optical flow algorithm has good adaptation in weak light and can improve the application range of polarization navigation *** research lays the foundation for day and night all-weather polarization navigation applications in future.

关键词： polarized optical flow algorithm imaging bionic polarization navigation micro sensor

Plasmon-enhanced fluorescence of gold nanoparticle/graphene quantum dots for detection of Cr^(3+)ions

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Photonics Research 2023年第10期11卷 1781-1790页

作者： YOU-LONG CHEN YI-HUA HU XING YANG YOU-LIN GU XIN-YU WANG YU-HAO XIA XIN-YUAN ZHANG YU-SHUANG ZHANG State key laboratory of Pulsed Power Laser technology National University of Defense TechnologyHefei 230037China key laboratory of Electronic Restriction of anhui province National University of Defense TechnologyHefei 230037China Advanced Laser technology laboratory of anhui province Hefei 230037China

Graphene quantum dots(GQDs),fascinating semiconductors with stable photoluminescence(PL),have important potential applications in the fields of biology,medicine,and new semiconductor ***,it is still challenging to overcome the weak PL ***,we report a strategy for selective resonance enhancement of GQD fluorescence using gold nanoparticles(AuNPs)as ***,the addition of low concentration AuNP makes AuNP/GQDs exhibit significant fluorescence enhancement of 2.67 times in the visible *** addition of high concentration AuNP leads to the formation of an excitation peak at 421 nm and selectively enhances certain radiation *** concluded that the main reason for the selective enhancement of PL intensity in high concentration AuNP is the transfer of generous hot electrons at high energy states from AuNP to GQD and relaxation to the ground *** electron resonance of low concentration AuNP transfers to GQD and relaxes to lower energy levels,exhibiting an overall enhancement of PL *** apply it for detection of the heavy metal ion Cr^(3+),and verify that it has a correlation coefficient of 97.36%.We believe AuNP/GQDs can be considered excellent candidates for heavy metal detection and high fluorescence bio-imaging.

关键词： quantum overcome excitation

Ultra-broadband,fast,and polarization-sensitive photoresponse of low-symmetry 2D NdSb_(2)

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Nano Research 2022年第6期15卷 5469-5475页

作者： Gang Li Hanlin Zhang Yong Li Shiqi Yin Xucai Kan Wensen Wei Haifeng Du Binghui Ge Chao An Mingliang Tian Feng Yan Sanjun Yang Tianyou Zhai Liang Li Institutes of Physical Science and Information technology Anhui UniversityHefei 230601China Engineering technology Research Center of Magnetic Materials School of Physics and Materials ScienceAnhui UniversityHefei 230601China anhui province key laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory of the Chinese Academy of ScienceHefei 230031China Department of Applied Physics The Hong Kong Polytechnic UniversityKowloonHong Kong 999077China State key laboratory of Materials Processing and Die and Mould technology School of Materials Science and EngineeringHuazhong University of Science and Technology(HUST)Wuhan 430074China

Broadband photodetectors with polarization-sensitive ability have received extraordinary attention for modern optoelectronic *** photodetectors should possess high responsivity,fast response,and good stability,which are rare to meet at the same time in one low-symmetric two-dimentional(2D)*** this work,neodymium diantimonides(RSb_(2)),a member of light rare-earth diantimonides RSb_(2)(R=La–Nd,Sm)with low-symmetry structure,is introduced as a fascinating highly anisotropic 2D material for broadband detection(532 nm to 4μm).The photodetector exhibits a responsivity of 0.49 mA·W^(−1)with 15μs response time at 532 nm and highly stable performance under ambient conditions over 8 ***,we identify the polarization-sensitive photoresponse of the detector and demonstrate a high anisotropic factor~*** addition,strong inplane anisotropy is revealed by anisotropic phonon response and the photodetection mechanism is investigated by scanning photocurrent microscopy *** pioneer work on RSb_(2)paves the way for further exploration of 2D RSb_(2)for high performance polarized photodetectors with fast photothermoelectric response.

关键词： ultra-broadband fast response polarization-sensitive photodetector RSb_(2)

Transverse Zeeman background correction method for air mercury measurement

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Chinese Physics B 2014年第10期23卷 458-463页

作者：李传新司福祺刘文清周海金江宇胡仁志 Department of Optics and Optical Engineering University of Science and Technology of China key laboratory of Environmental Optics and technology. anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences

By utilizing a natural mercury lamp, the transverse Zeeman background correction method, which is used for trace mercury measurement in air, is studied. In this paper, a natural mercury lamp is used as a light source, and is placed in a 1.78-T magnetic field. The lamp emits two linearly polarized light beams σ± and π of 253.65-nm resonance line, which are used as bias light and absorbing light, respectively. A polarization modulation system is used to allow σ± and π light beams to pass through alternately with a certain frequency. A multipath optical cell with 12-m optical path is used to increase optical distance. Based on the system described above, the influence caused by UV absorbing gases, such as NO2, SO2, acetone, benzene, and O3, is analyzed. The results show that it may reduce the detection limit when the concentrations of these gases exceed 83.4 ppm, 20.3 ppm, 142.3 ppm, 0.85 ppm, and 0.55 ppm, respectively. The detection limit of the system is calculated and can achieve up to 1.44 ng/m3 in 10 minutes. Measurements on mercury sample gas and air are carded out, and the measured data are compared with the data of RA-915 mercury analyzer （Russia）. The result shows that the correlation coefficient reaches up to 0.967. The experimental results indicate that the transverse Zeeman background correction method can be used to quantify trace mercury in air with high-precision.

关键词： transverse Zeeman background correction natural mercury lamp magnetic field multipath opticalcell