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Effect of matrix thermal properties on laser-induced plasma

Chinese physics B 2024年第10期33卷 331-336页

作者： Yuheng Shan An Li Xinyu Zhang Wen Yi Ying Zhang Xiaodong Liu Ruibin Liu Key Laboratory of Precision Spectroscopy and Optoelectronic Technology School of PhysicsBeijing Institute of TechnologyBeijing 100081China

The matrix thermal properties have an important impact on laser-induced plasma,as the thermal effect dominates the interaction between ns-pulsed laser and matter,especially in *** used a series of pure metals and aluminum alloys to measure plasma temperature and electron density through laser-induced breakdown spectroscopy,in order to investigate the effect of matrix thermal properties on laser-induced *** pure metals,a significant negative linear correlation was observed between the matrix thermal storage coefficient and plasma temperature,while a weak correlation was observed with electron *** results indicate that metals with low thermal conductivity or specific heat capacity require less laser energy for thermal diffusion or melting and evaporation,resulting in higher ablation rates and higher plasma ***,considering ionization energy,thermal effects may be a secondary factor affecting electron *** experiment of aluminum alloy further confirms the influence of thermal conductivity on plasma temperature and its mechanism explanation.

关键词： laser-induced plasma thermal properties matrix effect thermal storage coefficient plasma temperature

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Topologically protected entanglement switching around exceptional points

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Light(Science & Applications) 2024年第8期13卷 1631-1644页

作者： Zan Tang Tian Chen Xing Tang Xiangdong Zhang Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of Technology100081 BeijingChina

The robust operation of quantum entanglement states is crucial for applications in quantum information,computing,and communications^(1–3).However,it has always been a great challenge to complete such a task because of decoherence and ***,we propose theoretically and demonstrate experimentally an effective scheme to realize robust operation of quantum entanglement states by designing quadruple degeneracy exceptional *** encircling the exceptional points on two overlapping Riemann energy surfaces,we have realized a chiral switch for entangled states with high *** to the topological protection conferred by the Riemann surface structure,this switching of chirality exhibits strong robustness against perturbations in the encircling ***,we have experimentally validated such a scheme on a quantum walk *** work opens up a new way for the application of non-Hermitian physics in the field of quantum information.

关键词： exceptional quantum Riemann

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Light(Science & Applications) 2024年第2期13卷 333-346页

作者： Yifan Sun Qian Li Ling-Jun Kong Xiangdong Zhang Key Laboratory of advanced optoelectronic quantum architecture and measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of Technology100081BeijingChina

Compared with electrical neural networks,optical neural networks(ONNs)have the potentials to break the limit of the bandwidth and reduce the consumption of energy,and therefore draw much attention in recent *** far,several types of ONNs have been ***,the current ONNs cannot realize the acceleration as powerful as that indicated by the models like quantum neural *** to construct and realize an ONN with the quantum speedup is a huge ***,we propose theoretically and demonstrate experimentally a new type of optical convolutional neural network by introducing the optical *** is called the correlated optical convolutional neural network(COCNN).We show that the COCNN can exhibit“quantum speedup”in the training *** character is verified from the two *** is the direct illustration of the faster convergence by comparing the loss function curves of the COCNN with that of the traditional convolutional neural network(CNN).Such a result is compatible with the training performance of the recently proposed quantum convolutional neural network(QCNN).The other is the demonstration of the COCNN’s capability to perform the QCNN phase recognition circuit,validating the connection between the COCNN and the ***,we take the COCNN analog to the 3-qubit QCNN phase recognition circuit as an example and perform an experiment to show the soundness and the feasibility of *** results perfectly match the theoretical *** proposal opens up a new avenue for realizing the ONNs with the quantum speedup,which will benefit the information processing in the era of big data.

关键词： process quantum convolution

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Controlled propagation and particle manipulation of off-axis-rotating elliptical Gaussian beams in strong nonlocal media

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Chinese physics B 2025年第3期34卷 415-422页

作者： Rong-Quan Chen Rui-Lin Xiao Wei Wang Xi-Xi Chu Yu-Qing Song Xu-Dong Hu Ming Chen Guangxi Key Laboratory of Optoelectronic Information Processing School of Optoelectronic EngineeringGuilin University of Electronic TechnologyGuilin 541004China School of Physics Anshan Normal UniversityAnshan 114007China

Off-axis-rotating elliptical Gaussian beams(Oare GB)oblique incidence in strong nonlocal medium exhibit novel propagation *** analytical expressions of semi-axial beam widths,and center-of-mass trajectory equations for transmitting off-axis-rotating elliptical Gaussian beams in strong nonlocal media are obtained using the ABCD transfer matrix *** study revealed that the trajectory of the mass's center in the cross-section can be controlled by changing the sizes of the Oare GB parameters c,d,ζ,and *** gradient force of the light field causes the spot region to form a spatial potential well in the media,and this spatial potential well can effectively capture *** particles captured by the light field can move along with the beam,realizing the effective manipulation of the particle *** laws may be applied to modulating the propagation path of light beams and optical tweezer technology.

关键词： nonlinear optics off-axis-rotating elliptical Gaussian beam orbital angular momentum

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Entangling two levitated charged nanospheres through Coulomb interaction

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Chinese physics B 2024年第7期33卷 352-359页

作者：李国耀尹璋琦 Center for Quantum Technology Research and Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements(MOE) School of PhysicsBeijing Institute of TechnologyBeijing 100081China

Limited by the thermal environment, the entanglement of a massive object is extremely difficult to generate. Based on a coherent scattering mechanism, we propose a scheme to generate the entanglement of two optically levitated nanospheres through the Coulomb interaction. Two nanospheres are charged and coupled to each other through the Coulomb *** this manner, the entanglement of two nanospheres is induced either under a weak/strong optomechanical coupling regime or under an ultra-strong optomechanical coupling regime. The charges, radius and distance of the two nanospheres are taken into consideration to enhance the Coulomb interaction, thereby achieving a higher degree of entanglement in the absence of ground-state cooling. The corresponding maximum entanglement can be attained as the dynamics of the system approaches the boundary between the steady and the unsteady regimes. This provides a useful resource for both quantum-enhanced sensing and quantum information processing, as well as a new platform for studying many-body physics.

关键词： quantum entanglement coherent scattering Coulomb interaction

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Joint Authentication Public Network Cryptographic key Distribution Protocol Based on Single Exposure Compressive Ghost Imaging

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Chinese physics Letters 2024年第2期41卷 47-56页

作者：俞文凯王硕飞商克谦 Center for Quantum Technology Research and Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement of Ministry of EducationSchool of PhysicsBeijing Institute of TechnologyBeijing 100081China

In the existing ghost-imaging-based cryptographic key distribution(GCKD)protocols,the cryptographic keys need to be encoded by using many modulated patterns,which undoubtedly incurs long measurement time and huge memory *** this,based on snapshot compressive ghost imaging,a public network cryptographic key distribution protocol is proposed,where the cryptographic keys and joint authentication information are encrypted into several color block diagrams to guarantee *** transforms the previous single-pixel sequential multiple measurements into multi-pixel single exposure measurements,significantly reducing sampling time and memory *** simulation and experimental results demonstrate the feasibility of this protocol and its ability to detect illegal ***,it takes GCKD a big step closer to practical applications.

关键词： ghost Ghost Authentication

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Gate-field control of valley polarization in valleytronics

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Chinese physics B 2024年第6期33卷 2-12页

作者：张婷婷韩依琳张闰午余智明 Institute of Physics Chinese Academy of SciencesBeijing 100190China Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic Systemsand School of PhysicsBeijing Institute of TechnologyBeijing 100081China

Valleytronics materials are a kind of special semiconductors which can host multiple symmetry-connected and wellseparated electron or hole pockets in the Brillouin zone when the system is slightly n or p doped. Since the low-energy particles residing in these pockets generally are not easily scattered to each other by small perturbations, they are endowed with an additional valley degree of freedom. Analogous to spin, the valley freedom can be used to process information,leading to the concept of valleytronics. The prerequisite for valleytronics is the generation of valley polarization. Thus,a focus in this field is achieving the electric generation of valley polarization, especially the static generation by the gate electric field alone. In this work, we briefly review the latest progress in this research direction, focusing on the concepts of the couplings between valley and layer, i.e., the valley–layer coupling which permits the gate-field control of the valley polarization, the couplings between valley, layer, and spin in magnetic systems, the physical properties, the novel designing schemes for electronic devices, and the material realizations of the gate-controlled valleytronics materials.

关键词： band structure electronic transport optical properties spintronics

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Secondary electron emission and photoemission from a negative electron affinity semiconductor with large mean escape depth of excited electrons

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Chinese physics B 2023年第4期32卷 677-690页

作者：谢爱根董红杰刘亦凡 School of Physics and Optoelectronic Engineering Nanjing University of Information Science and TechnologyNanjing 210044China Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean Nanjing University of Information Science&TechnologyNanjing 210044China Jiangsu international Joint Laboratory on Meteorological Photonics and Optoelectronic Detection Nanjing University of Information Science&TechnologyNanjing 210044China

The formulae for parameters of a negative electron affinity semiconductor(NEAS)with large mean escape depth of secondary electrons A(NEASLD)are *** methods for obtaining parameters such asλ,B,E_(pom)and the maximumδandδat 100.0 keV≥E_(po)≥1.0 keV of a NEASLD with the deduced formulae are presented(B is the probability that an internal secondary electron escapes into the vacuum upon reaching the emission surface of the emitter,δis the secondary electron yield,E_(po)is the incident energy of primary electrons and E_(pom)is the E_(po)corresponding to the maximumδ).The parameters obtained here are analyzed,and it can be concluded that several parameters of NEASLDs obtained by the methods presented here agree with those obtained by other *** relation between the secondary electron emission and photoemission from a NEAS with large mean escape depth of excited electrons is investigated,and it is concluded that the presented method of obtaining A is more accurate than that of obtaining the corresponding parameter for a NEAS with largeλ_(ph)(λ_(ph)being the mean escape depth of photoelectrons),and that the presented method of calculating B at E_(po)>10.0 keV is more widely applicable for obtaining the corresponding parameters for a NEAS with largeλ_(ph).

关键词： negative electron affinity semiconductor secondary electron emission photoemission the probability secondary electron yield large mean escape depth of excited electrons

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Effective integration of highly-efficient focusing apodized grating and quantum dots on a solid substrate for scalable quantum photonic circuits

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Science China(physics,Mechanics & Astronomy) 2024年第9期67卷 99-107页

作者： Beimeng Yao Rongbin Su Shunfa Liu Changkun Song Ying Yu Jin Liu Xuehua Wang State Key Laboratory of Optoelectronic Materials and Technologies School of PhysicsSun Yat-sen UniversityGuangzhou 510275China State Key Laboratory of Optoelectronic Materials and Technologies School of Electronics and Information TechnologySun Yat-sen UniversityGuangzhou 510275China

Recent advancements in quantum photonic circuits have significantly influenced the field of quantum information *** pursuit of an integrated quantum photonic circuit that offers an active,stable platform for large-scale integration and high processing efficiency remains a key *** grating coupler,as a crucial element for an efficient transformation output interface in the integrated quantum photonic circuits,presents significant potential for practical ***,we demonstrate the integration block of a highly efficient shallow-etched focusing apodized grating coupler with indium arsenide(InAs)quantum dots(QDs)in gallium arsenide(GaAs)on a SiO2substrate for active quantum photonic *** designed grating couplers possess a high efficiency over 90% in the broadband(900-930 nm)from the circuit to free space,and a nearly-perfect match with the fiber ***,the efficiency to free space reaches 81.8%,and the match degree with the fiber mode is high up to 92.1%.The proposed integration block offers the potential for large-scale integration of active quantum photonic circuits due to its stable solid substrate and highly performant output for quantum measurements.

关键词： quantum dot grating coupler wafer bonding quantum photonic circuit

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Efficiently simulating the work distribution of multiple identical bosons with boson sampling

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Frontiers of physics 2024年第3期19卷 197-206页

作者： Wen-Qiang Liu Zhang-qi Yin Center for Quantum Technology Research and Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements(MOE) School of PhysicsBeijing Institute of TechnologyBeijing 100081China

Boson sampling has been theoretically proposed and experimentally demonstrated to show quantum computational ***,it still lacks the deep understanding of the practical applications of boson *** we propose that boson sampling can be used to efficiently simulate the work distribution of multiple identical *** link the work distribution to boson sampling and numerically calculate the transition amplitude matrix between the single-boson eigenstates in a one-dimensional quantum piston system,and then map the matrix to a linear optical network of boson *** work distribution can be efficiently simulated by the output probabilities of boson sampling using the method of the grouped probability *** scheme requires at most a polynomial number of the samples and the optical *** work opens up a new path towards the calculation of complex quantum work distribution using only photons and linear optics.

关键词： quantum simulation quantum work distribution boson sampling linear optic

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