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Four-wave mixing Bragg scattering for small frequency shift from silicon coupled microrings

Chinese Physics B 2025年第1期34卷 351-355页

作者： Chang Zhao Chao Wu Pingyu Zhu Yuxing Du Yan Wang Miaomiao Yu Kaikai Zhang Ping Xu Institute for Quantum Information&State Key Laboratory of High Performance Computing College of Computer Science and TechnologyNational University of Defense TechnologyChangsha 410073China

Frequency conversion is pivotal in nonlinear optics and quantum optics for manipulating and translating light signals across different wavelength *** frequency conversion between two light beams with a small frequency interval is a central *** this work,we design a pair of coupled silicon microrings wherein coupled-induced modesplitting exists to achieve a small frequency shift by the process of four-wave mixing Bragg *** an example,the signal can be up or down converted to the idler which is 15.5 GHz spaced when two pumps align with another pair of split *** results unveil the potential of coupled microring resonators for small interval frequency conversion in a high-fidelity,all-optical,and signal processing quantum frequency interface.

关键词： four-wave mixing Bragg scattering silicon coupled microrings

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A fully connected polarization-entangled network via integrated spontaneous four-wave mixing engineering

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Science China(Physics,Mechanics & Astronomy) 2025年第06期Mechanics & Astronomy) .卷 76-83页

作者： Pingyu Zhu Yan Wang Yuxing Du Miaomiao Yu Kaikai Zhang Kun Wang Ping Xu Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer Science and TechnologyNational University of Defense Technology Hefei National Laboratory

quantum communication is rapidly developing and is gradually being commercialized due to its technological maturity. Establishing dense communication links among multiple users in a scalable and efficient way is of great significance for realizing a large-scale quantum communication network. Here, we propose a novel scheme to construct a fully connected polarizationentangled network, utilizing the engineering of spontaneous four-wave mixings(SFWMs) and a path-polarization converter. It does not require active optical switches which limit the communication speed, or trusted nodes which lead to potential security risks. The required frequency channels in the network grow linearly with the number of users. We experimentally demonstrate a six-user fully connected network with on-chip SFWM processes motivated by four pumps. Each user in the network receives a frequency channel, and all fifteen connections between the users are implemented simultaneously. Our work opens up a promising scheme to efficiently construct fully connected large-scale networks.

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Ultra-low power MoS2 optoelectronic synapse with wavelength sensitivity for color target recognition

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Science China(information Sciences) 2025年第4期68卷 187-196页

作者： Bo WEI Yabo CHEN Xiaotong HAN Yan KANG Bujia LIANG Cheng LI Xiaokuo YANG Liang FANG Yuanxi PENG Institute for Quantum Information & State Key Laboratory of High Performance Computing College of ComputerNational University of Defense Technology Fundamentals Department Air Force Engineering University College of Advanced Interdisciplinary Studies National University of Defense Technology Institute of Quantum Information Science and Technology College of ScienceNational University of Defense Technology College of Computer National University of Defense Technology

Optoelectronic synapses that integrate visual perception and pre-processing hold significant potential for neuromorphic vision systems（NVSs）. However, due to a lack of wavelength sensitivity, existing NVS mainly focuses on gray-scale image processing, making it challenging to recognize color images. Additionally, the high power consumption of optoelectronic synapses, compared to the 10 fJ energy consumption of biological synapses, limits their broader application. To address these challenges, an energy-efficient NVS capable of color target recognition in a noisy environment was developed,utilizing a MoS2optoelectronic synapse with wavelength sensitivity. Benefiting from the distinct photon capture capabilities of 450, 535, and 650 nm light, the optoelectronic synapse exhibits wavelength-dependent synaptic plasticity, including excitatory postsynaptic current（EPSC）, paired-pulse facilitation（PPF）, and long-term plasticity（LTP）. These properties can effectively mimic the visual memory and color discrimination functions of the human vision system. Results demonstrate that the NVS, based on MoS2optoelectronic synapses, can eliminate the color noise at the sensor level, increasing color image recognition accuracy from 50% to 90%. Importantly, the optoelectronic synapse operates at a low voltage spike of0.0005 V, consuming only 0.075 fJ per spike, surpassing the energy efficiency of both existing optoelectronic and biological synapses. This ultra-low power, color-sensitive device eliminates the need for color filters and offers great promise for future deployment in filter-free NVS.

关键词： optoelectronic synapse neuromorphic vision system color recognition 2D materials image pre-processing

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Passive on-chip isolators based on the thin-film lithium niobate platform

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Chinese Physics B 2025年第3期34卷 408-413页

作者： Jiacheng Liu Gongyu Xia Qilin Hong Pingyu Zhu Kai-Kai Zhang keyu Xia Ping Xu Shiqiao Qin Zhihong Zhu College of Advanced Interdisciplinary Studies&Hunan Provincial Key Laboratory of Novel Nano Optoelectronic Information Materials and Devices National University of Defense TechnologyChangsha 410073China Institute for Quantum Information and State Key Laboratory of High-Performance Computing College of Computer Science and TechnologyNational University of Defense TechnologyChangsha 410073China College of Engineering and Applied Sciences National Laboratory of Solid State Microstructuresand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210023China

Optical isolators,the photonic analogs of electronic diodes,are essential for ensuring the unidirectional flow of light in optical systems,thereby mitigating the destabilizing effects of back ***-film lithium niobate(TFLN),hailed as“the silicon of photonics,”has emerged as a pivotal material in the realm of chip-scale nonlinear optics,propelling the demand for compact optical *** report a breakthrough in the development of a fully passive,integrated optical isolator on the TFLN platform,leveraging the Kerr effect to achieve an impressive 10.3 dB of isolation with a minimal insertion loss of 1.87 *** theoretical simulations have demonstrated that our design,when applied to a microring resonator with a Q factor of 5×10^(6),can achieve 20 dB of isolation with an input power of merely 8 *** advancement underscores the immense potential of lithium niobate-based Kerr-effect isolators in propelling the integration and application of high-performance on-chip lasers,heralding a new era in integrated photonics.

关键词： thin-film lithium niobate Kerr effect optical isolator

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Coupled-mode phase matching on a silicon chip

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Physical Review A 2025年第3期111卷 033504-033504页

作者： Chao Wu Pingyu Zhu Miaomiao Yu Weihong Luo Qilin Zheng Kaikai Zhang Yingwen Liu Ping Xu Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha 410073 China Hefei National Laboratory Hefei 230088 China

Phase matching lies at the heart of the classical nonlinear process for frequency conversion and all-optical processing, as well as the spontaneous parametric process for the quantum light sources generation. In this work, we experimentally demonstrate the coupled-mode phase-matching (CMPM) engineered by the two-paralleled-coupled waveguides on a silicon-on-insulator (SOI) chip, extending the converted beam and entangled photons to the S band and L band. We measure the spectrum and efficiency of wavelength conversion, which successfully validates the designed CMPM scheme. We further measure the pairs generation rate of the biphoton based on the spontaneous four-wave mixing, which features a narrow bandwidth consistent well with the theoretical simulations. Multiple CMPM conditions can be achieved by exploiting the combinations of even and odd supermodes of the coupled system and tuned by designing a proper coupling gap between the two waveguides. The CMPM can extend the FWM nonlinear process ranging from the O band to the U band and even the midinfrared, enriching the working wavelength to a large extent. In addition, the CMPM features a discrete-band narrow bandwidth, which will greatly enhance the encoding density of frequency and the spectral purity of generated photon. In addition, our methods can be easily extended to a wide range of materials such as silicon nitride, dispensing with the dispersion engineering for phase matching.

关键词： Silicon nitride

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Distinct ultrafast dynamics of bilayer and trilayer nickelate superconductors regarding the density-wave-like transitions

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Science Bulletin 2025年第2期70卷 180-186页

作者： Yidian Li Yantao Cao Liangyang Liu Pai Peng Hao Lin Cuiying Pei Mingxin Zhang Heng Wu Xian Du Wenxuan Zhao Kaiyi Zhai Xuefeng Zhang Jinkui Zhao Miaoling Lin Pingheng Tan Yanpeng Qi Gang Li Hanjie Guo Luyi Yang Lexian Yang State Key Laboratory of Low Dimensional Quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China Key Lab for Magnetism and Magnetic Materials of the Ministry of Education Lanzhou UniversityLanzhou 730000China Songshan Lake Materials Laboratory Dongguan 523808China School of Physical Science and Technology ShanghaiTech University and CAS-Shanghai Science Research CenterShanghai 201210China State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China ShanghaiTech Laboratory for Topological Physics Shanghai 200031China Laboratory of High-resolution Electron Microscopy ShanghaiTech UniversityShanghai 201210China Frontier Science Center for Quantum Information Beijing 100084China

In addition to the pressurized high-temperature superconductivity,bilayer and trilayer nickelate superconductors La_(n+1)Ni_(n)O_(3n+1)(n=2 and 3)exhibit many intriguing properties at ambient pressure,such as orbital-dependent electronic correlation,non-Fermi liquid behavior,and density-wave ***,using ultrafast reflectivity measurement,we observe a drastic difference between the ultrafast dynamics of the bilayer and trilayer nickelates at ambient *** observe a coherent phonon mode in La_(4)Ni_(3)O_(10)involving the collective vibration of La,Ni,and O atoms,which is absent in La_(3)Ni_(2)O_(7).Temperature-dependent relaxation time diverges near the density-wave transition temperature of La_(4)Ni_(3)O_(10),while it is inversely proportional to the temperature in La_(3)Ni_(2)O_(7)above~150 K,suggesting a non-Fermi liquid behavior of La_(3)Ni_(2)O_(7).Moreover,we estimate the electron–phonon coupling constants to be 0.05–0.07 and 0.12–0.16 for La_(3)Ni_(2)O_(7)and La_(4)Ni_(3)O_(10),respectively,suggesting a relatively minor role of electron–phonon coupling in the electronic properties of La_(n+1)Ni_(n)O_(3n+1)at ambient *** relevant microscopic interaction and dynamic information are essential for further studying the interplay between superconductivity and density-wave transitions in nickelate superconductors.

关键词： Nickelate superconductors Density-wave state Ultrafast dynamics Electron-phonon coupling Coherent phonon

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quantum metric induced oscillations in nearly dispersionless flat bands

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Physical Review B 2025年第12期111卷 L121102-L121102页

作者： Hui Zeng Zijian Zhou Wenhui Duan Huaqing Huang State Key Laboratory of Low-Dimensional Quantum Physics Department of Physics Tsinghua University Beijing 100084 China School of Physics Peking University Beijing 100871 China Institute for Advanced Study Tsinghua University Beijing 100084 China Frontier Science Center for Quantum Information Beijing 100084 China Collaborative Innovation Center of Quantum Matter Beijing 100871 China Center for High Energy Physics Peking University Beijing 100871 China

The transport of Bloch electrons under strong fields is traditionally understood through two mechanisms: intraband Bloch oscillations and interband Zener tunneling. Here, we propose an oscillation mechanism induced by the interband quantum metric, which would significantly affect the electron dynamics under strong fields. By considering the multiband dynamics to the second order of the density matrix, we reveal that quantum metric induced oscillations (QMOs) persist regardless of band dispersion, even in exactly dispersionless flat bands. The resultant drift current can reach a magnitude comparable to the Bloch oscillation induced drift current in systems where interband tunneling is negligible. Notably, the QMO induced drift current increases linearly with electric field strength under the constraints of time-reversal or spatial-inversion symmetry, emerging as the primary delocalized current. We further show that both one-dimensional and two-dimensional superlattices are potential platforms for investigating QMO.

关键词： Electric fields

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A survey on deep learning for polyp segmentation: techniques, challenges and future trends

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Visual Intelligence 2025年第1期3卷 1-20页

作者： Mei, Jiaxin Zhou, Tao Huang, Kaiwen Zhang, Yizhe Zhou, Yi Wu, Ye Fu, Huazhu PCA Lab Key Laboratory of Intelligent Perception and Systems for High-Dimensional Information of Ministry of Education Nanjing China School of Computer Science and Engineering Nanjing University of Science and Technology Nanjing China School of Computer Science and Engineering Southeast University Nanjing China Institute of High Performance Computing A*STAR Singapore Singapore

Early detection and assessment of polyps play a crucial role in the prevention and treatment of colorectal cancer (CRC). Polyp segmentation provides an effective solution to assist clinicians in accurately locating and segmenting polyp regions. In the past, people often relied on manually extracted lower-level features such as color, texture, and shape, which often had problems capturing global context and lacked robustness to complex scenarios. With the advent of deep learning, more and more medical image segmentation algorithms based on deep learning networks have emerged, making significant progress in the field. This paper provides a comprehensive review of polyp segmentation algorithms. We first review some traditional algorithms based on manually extracted features and deep segmentation algorithms, and then describe benchmark datasets related to the topic. Specifically, we carry out a comprehensive evaluation of recent deep learning models and results based on polyp size, taking into account the focus of research topics and differences in network structures. Finally, we discuss the challenges of polyp segmentation and future trends in the field. © The Author(s) 2025.

关键词： Comprehensive evaluation Deep learning Medical imaging Polyp segmentation

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Pronounced advance on typhoon track forecast with global convection-permitting model

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Science Bulletin 2025年第9期70卷 1424-1428页

作者： Gu, Jun Zhao, Chun Li, Gudongze Feng, Jiawang Xu, Mingyue Du, Qiuyan Xia, Zihan Li, Yubin Chen, Guanghua Hao, Xiaoyu Chen, Junshi An, Hong Deep Space Exploration Laboratory / School of Earth and Space Sciences / CMA-USTC Laboratory of Fengyun Remote Sensing / State Key Laboratory of Fire Science / Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software University of Science and Technology of China Hefei230026 China Laoshan Laboratory Qingdao266237 China CAS Center for Excellence in Comparative Planetology University of Science and Technology of China Hefei230026 China School of Atmospheric Physics Nanjing University of Information Science and Technology Nanjing210044 China Key Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric Physics Chinese Academy of Sciences Beijing100029 China School of Computer Science and Technology University of Science and Technology of China Hefei230026 China

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Precise spectroscopy of metastable Li+using the optical Ramsey technique in support of time dilation tests

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Photonics Research 2025年第1期13卷 201-209页

作者： PENG-PENG ZHOU SHAO-LONG CHEN CHENG-GANG QIN XU-RUI CHANG ZHI-QIANG ZHOU WEI SUN YAO HUANG KE-LIN GAO HUA GUAN State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China Information Engineering University Zhengzhou 450001China Key Laboratory of Time Reference and Applications Chinese Academy of SciencesWuhan 430206China MOE Key Laboratory of Fundamental Physical Quantities Measurement&Hubei Key Laboratory of Gravitation and Quantum Physics PGMF and School of PhysicsHuazhong University of Science and TechnologyWuhan 430074China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Green and High-end Utilization of Salt Lake Resources Qinghai Institute of Salt LakesChinese Academy of SciencesXining 810008China Wuhan Institute of Quantum Technology Wuhan 430206China

Time dilation constitutes a crucial aspect of Lorentz invariance within special relativity and undergoes constant scrutiny through numerous Ives-Stilwell-type experiments employing the Doppler *** our study,we employed optical Ramsey spectroscopy on a Li^(+)ion beam to enhance the precision of measuring the intrinsic transition frequency 23S1-23P2 to the level of four parts in 1010 with speed of *** findings reconciled an existing 2 MHz disparity between collinear and perpendicular laser ***,in conjunction with previous studies on Li^(+)ion beams traveling at speeds of 0.064c and 0.338c[***.3,861(2007);***.113,120405(2014)],we updated the Robertson-Mansouri-Sexl parameterαto be(-10.0±9.9)×10^(-8)and(-2.9±2.0)×10^(-8),respectively.

关键词： spectroscopy effect Ramsey

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