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Enhancement of spatial resolution of ghost imaging via localizing and thresholding

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Chinese Physics B 2019年第4期28卷 190-195页

作者： Yunlong Wang Yingnan Zhou Shaoxiong Wang Feiran Wang Ruifeng Liu Hong Gao Pei Zhang Fuli Li Shaanxi Provincial key laboratory for quantum information and quantum Optoelectronic Devices and Department of Applied PhysicsSchool of Science Xi'an Jiaotong University

In ghost imaging, an illumination light is split into test and reference beams which pass through two different optical systems respectively and an image is constructed with the second-order correlation between the two light beams. Since both light beams are diffracted when passing through the optical systems, the spatial resolution of ghost imaging is in general lower than that of a corresponding conventional imaging system. When Gaussian-shaped light spots are used to illuminate an object, randomly scanning across the object plane, in the ghost imaging scheme, we show th√at by localizing central positions of the spots of the reference light beam, the resolution can be increased by a factor of 2^(1/2) same as that of the corresponding conventional imaging system. We also find that the resolution can be further enhanced by setting an appropriate threshold to the bucket measurement of ghost imaging.

关键词： ghost imaging localization thresholding post-selection resolution enhancement

Security analysis of satellite-to-ground reference-frame-independent quantum key distribution with beam wandering

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Chinese Physics B 2024年第8期33卷 192-201页

作者：周淳赵燕美杨晓亮陆宜飞周雨姜晓磊汪海涛汪洋李家骥江木生汪翔张海龙李宏伟鲍皖苏 Henan key laboratory of quantum information and Cryptography SSF IEUZhengzhou 450001China Synergetic Innovation Centre of quantum information and quantum Physics University of Science and Technology of ChinaHefei 230026China

The reference-frame-independent(RFI)quantum key distribution(QKD)is suitable for satellite-based links by removing the active alignment on the reference ***,how the beam wandering influences the performance of RFI-QKD remains a pending issue in satellite-to-ground *** this paper,based on the mathematical model for characterizing beam wandering,we present the security analysis for satellite-to-ground RFI-QKD and analytically derive formulas for calculating the secret key rate with beam *** simulation results show that the performance of RFI-QKD is better than the Bennett–Brassard 1984(BB84)QKD with beam wandering in asymptotic ***,the degree of influences of beam wandering is specifically presented for satellite-to-ground RFI-QKD when statistical fluctuations are taken into *** work can provide theoretical support for the realization of RFI-QKD using satellite-to-ground links and have implications for the construction of large-scale satellite-based quantum networks.

关键词： quantum key distribution satellite-to-ground beam wandering

Collapse–revival of squeezing of two atoms in dissipative cavities

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Chinese Physics B 2016年第7期25卷 145-150页

作者：邹红梅方卯发 key laboratory of Low-dimensional quantum Structures and quantum Control of Ministry of Education College of Physics and Information Science Hunan Normal University

Based on the time-convolutionless master-equation approach, we investigate the squeezing dynamics of two atoms in dissipative cavities. We find that the atomic squeezing is related to initial atomic states, atom–cavity couplings, nonMarkovian effects and resonant frequencies of an atom and its cavity. The results show that a collapse–revival phenomenon will occur in the atomic squeezing and this process is accompanied by the buildup and decay of entanglement between two atoms. Enhancing the atom–cavity coupling can increase the frequency of the collapse–revival of the atomic *** stronger the non-Markovian effect is, the more obvious the collapse–revival phenomenon is. In particular, if the atom–cavity coupling or the non-Markovian effect is very strong, the atomic squeezing will tend to a stably periodic oscillation in a long time. The oscillatory frequency of the atomic squeezing is dependent on the resonant frequency of the atom and its cavity.

关键词： collapse–revival atomic squeezing atom–cavity coupling non-Markovian effect

Population dynamics of excited atoms in non-Markovian environments at zero and finite temperature

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Chinese Physics B 2015年第8期24卷 177-182页

作者：邹红梅方卯发 key laboratory of Low-dimensional quantum Structures and quantum Control of Ministry of Education College of Physics and Information Science Hunan Normal University

The population dynamics of a two-atom system, which is in two independent Lorentzian reservoirs or in two independent Ohmic reservoirs respectively, where the reservoirs are at zero temperature or finite temperature, is studied by using the time-convolutionless master-equation method. The influences of the characteristics and temperature of a non-Markovian environment on the population of the excited atoms are analyzed. We find that the population trapping of the excited atoms is related to the characteristics and the temperature of the non-Markovian environment. The results show that, at zero temperature, the two atoms can be effectively trapped in the excited state both in the Lorentzian reservoirs and in the Ohmic reservoirs. At finite temperature, the population of the excited atoms will quickly decay to a nonzero value.

关键词： population excited atom non-Markovian environment temperature

Noisy teleportation of qubit states via the Greenberger-Horne-Zeilinger state or the W state

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Chinese Physics B 2010年第6期19卷 58-65页

作者：李艳玲方卯发肖兴吴超侯丽珍 key laboratory of Low-Dimensional quantum Structures and quantum Control Ministry of EducationCollege of Physics and Information ScienceHunan Normal University

The effects of distributing entanglement through the amplitude damping channel or the phase damping channel on the teleportation of a single-qubit state via the Greenberger Horne-Zeilinger state and the W state are discussed. It is found that the average fidelity of teleportation depends on the type and rate of the damping in the channel. For the one-qubit affected case, the Greenberger-Horne Zeilinger state is as robust as the W state, i.e., the same quantum information is preserved through teleportation. For the two-qubit affected case, the W state is more robust when the entanglement is distributed via the amplitude damping channel; if the entanglement is distributed via the phase damping channel, the W state is more robust when the noisy parameter is small while the Greenberger-Horne-Zeilinger state becomes more robust when it is large. For the three-qubit affected case, the Greenberger-Horne-Zeilinger state is more robust than the W state.

关键词： noisy teleportation amplitude damping channel phase damping channel

High Lattice Match Growth of InAsSb Based Materials by Molecular Beam Epitaxy

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Chinese Physics Letters 2016年第12期33卷 133-137页

作者：任洋郝瑞亭刘思佳郭杰王国伟徐应强牛智川 key laboratory of Renewable Energy Advanced Materials and Manufacturing Technology(Ministry of Education) Provincial Key Laboratory of Rural Energy EngineeringInstitute of Solar EnergyYunnan Normal University State key laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of Sciences Synergetic Innovation Center of quantum information and quantum Physics University of Science and Technology of China

High lattice match growth of InAsSb based materials on GaSb substrates is demonstrated. The present results indicate that a stable substrate temperature and the optimal flux ratios are of critical importance in achieving a homogeneous InAsSb based material composition throughout the growth period. The quality of these epilayers is assessed using a high-resolution x-ray diffraction and atomic force microscope. The mismatch between the GaSb substrate and InAsSb alloy achieves almost zero, and the rms surface roughness of InAsSb alloy achieves around 1.7A over an area of 28μm × 28μm. At the same time, the mismatches between GaSb and InAs/InAs0.73Sb0.27 superlattices （SLs） achieve approximately 100 arcsec （75 periods） and zero （300 periods）, with the surface rms roughnesses of InAs/InAs0.73Sb0.27 SLs around 1.8 A （75 periods） and 2.1A （300 periods） over an area of 20 μm×20 μm, respectively. After fabrication and characterization of the devices, the dynamic resistance of the n-barrier-n InAsSb photodetector near zero bias is of the order of 10^6Ω·cm^2. At 77K, the positive-intrinsic-negative photodetectors are demonstrated in InAsSb and InAs/InAsSb SL （75 periods） materials, exhibiting fifty-percent cutoff wavelengths of 3.8μm and 5.1μm, respectively.

关键词： InAsSb as is GaSb on in High Lattice Match Growth of InAsSb Based Materials by Molecular Beam Epitaxy of by

The geographical distribution of grey wolves (Canis lupus) in China:a systematic review

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Zoological Research 2016年第6期37卷 315-326页

作者： Lu WANG Ya-Ping MA Qi-Jun ZHOU Ya-Ping ZHANG Peter SAVOLAINEN Guo-Dong WANG State key laboratory for Conservation and Utilization of Bio-resources in yunnan Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan ProvinceYunnan University State key laboratory of Genetic Resources and Evolution Yunnan Key Laboratory of Molecular Biology of Domestic AnimalsKunming Institute of ZoologyChinese Academy of Sciences Science for Life laboratory Department of Gene TechnologyKTH-Royal Institute of Technology

The grey wolf （Canis lupus） is one of the most widely distributed terrestrial mammals, and its distribution and ecology in Europe and North America are largely well described. However, the distribution of grey wolves in southern China is still highly controversial. Several well-known western literatures stated that there were no grey wolves in southern China, while the presence of grey wolves across China has been indicated in A Guide to the Mammals of China, published by Princeton University Press. It is essential to solve this discrepancy since dogs may have originated from grey wolves in southern China. Therefore, we systematically investigated Chinese literatures about wild animal surveys and identified more than 100 articles and books that included information of the distribution of grey wolves in China. We also surveyed the collections of three Chinese natural museums and found 26 grey wolf skins specimens collected across China. Moreover, we investigated the fossil records in China and identified 25 archaeological sites with wolf remains including south China. In conclusion, with the comprehensive summary of Chinese literatures, museum specimens and fossil records, we demonstrate that grey wolves do distribute across all parts of the Chinese mainland, including the most southern parts.

关键词： China Grey wolf Distribution Conservation

Laser cooling with adiabatic passage for type-Ⅱ transitions

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Frontiers of physics 2021年第3期16卷 193-203页

作者： Qian Liang Tao Chen Wen-Hao Bu Yu-He Zhang Bo Yan Interdisciplinary Center of quantum information State Key Laboratory of Modern Optical InstrumentationZhejiang Province Key Laboratory of Quantum Technology and DeviceDepartment of PhysicsZhejiang UniversityHangzhou310027China Collaborative Innovation Centre of Advanced Microstructures Nanjing UniversityNanjing210093China key laboratory of quantum Optics Chinese Academy of SciencesShanghai200800China

We extend the idea of laser cooling with adiabatic passage to multi-level type-Ⅱ *** find the cooling force can be significantly enhanced when a proper magnetic field is *** is because the magnetic field decomposes the multi-level system into several two-level sub-systems,hence the stimulated absorption and stimulated emission can occur in order,allowing for the multiple photon momentum *** show that this scheme also works on the laser-coolable molecules with a better cooling effect compared to the conventional Doppler cooling.A reduced dependence on spontaneous emission based on our scheme is observed as *** results suggest this scheme is very feasible for laser cooling of polar molecules.

关键词： laser cooling of polar molecule adiabatic passage type-Ⅱtransition cold molecule cold atom

Generation and characterization of customized Laguerre–Gaussian beams with arbitrary profiles

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Frontiers of physics 2024年第4期19卷 235-241页

作者： Chengyuan Wang Yun Chen Jinwen Wang Xin Yang Hong Gao Fuli Li Ministry of Education key laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter Shaanxi Province Key Laboratory of Quantum Information and Quantum Optoelectronic DevicesSchool of PhysicsXi’an Jiaotong UniversityXi’an 710049China Department of Physics Huzhou UniversityHuzhou 313000China

We experimentally demonstrate the generation of customized Laguerre–Gaussian(LG)beams whose intensity maxima are localized around any desired *** principle is to act with appropriate algebraic functions on the angular spectra of LG *** characterize the propagation properties of these beams and compare them with non-diffraction caustic beams possessing the same intensity *** results manifest that the customized-LG beams can maintain their profiles during propagation and suffer less energy loss than the non-diffraction caustic beams,and hence are able to propagate a longer ***,the customized-LG beam exhibits self-healing ability when parts of their bodies are *** new structure beam has potential applications in areas such as optical communication,soliton routing and steering,and optical tweezing.

关键词： light manipulation wave propagation invariant optical fields