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Precision measurement of M1 optical clock transition in Ni12+

Physical Review Research 2024年第1期6卷 013030-013030页

作者： Shaolong Chen Zhiqiang Zhou Jiguang Li Tingxian Zhang Chengbin Li Tingyun Shi Yao Huang Kelin Gao Hua Guan State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan 430071 China University of Chinese Academy of Sciences Beijing 100049 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China School of Science Lanzhou University of Technology Lanzhou 730050 China Wuhan Institute of Quantum Technology Wuhan 430206 China

Highly charged ions (HCIs) have drawn significant interest in quantum metrology and in the search for new physics. Among these, Ni12+ is considered as one of the most promising candidates for the next generation of HCI optical clocks, due to its two E1-forbidden transitions M1 and E2, which occur in the visible spectral range. In this work, we used the Shanghai-Wuhan electron beam ion trap to perform a high-precision measurement of the M1 transition wavelength. Our approach involved an improved calibration scheme for the spectra, utilizing auxiliary Ar+ lines for calibration and correction. Our final measured result of the M1 transition wavelength demonstrates a fivefold improvement in accuracy compared to our previous findings, reaching the subpicometer level accuracy. In combination with our rigorous atomic-structure calculations to capture the electron correlations and relativistic effects, the quantum electrodynamic corrections were extracted.

关键词： Atomic spectra Atomic, optical & lattice clocks Fine & hyperfine structure Optical pumping

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Multiphoton fusion of light nuclei in intense laser fields

arXiv

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arXiv 2023年

作者： Wu, Binbing Fan, Zhengfeng Ye, Difa Ye, Tao Gao, Congzhang Yu, Chengxin Xu, Xuefeng Zhang, Cunbo Liu, Jie Institute of Applied Physics and Computational Mathematics Beijing100088 China Graduate School China Academy of Engineering Physics Beijing100193 China CAPT HEDPS IFSA Collaborative Innovation Center of MoE Peking University Beijing100871 China

We investigate the fusion cross sections of light nuclei in the presence of linearly polarized intense laser fields. By combining the Coulomb-Volkov solutions with the complex spherical square-well nuclear potential, we derive an explicit formulation of the multiphoton cross section in a self-consistent manner. Our analysis is specifically focused on deuteron-triton (DT) and proton-boron (p 11B) fusion reactions, both of which have garnered widespread attention. The theoretical results reveal that, under conditions of longer laser wavelengths and lower incident particle kinetic energies, a few thousands of photons can participate in the fusion reactions, resulting in a substantial enhancement of fusion cross sections by almost ten orders of magnitude. We elucidate the multiphoton mechanism underlying these findings and discuss their implications. Copyright © 2023, The Authors. All rights reserved.

关键词： Kinetic energy

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State-of-the-art advances in vacancy defect engineering of graphitic carbon nitride for solar water splitting

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Journal of Semiconductors 2023年第8期44卷 16-34页

作者： Jie Li Kaige Huang Yanbin Huang Yumin Ye Marcin Ziółek Zhijie Wang Shizhong Yue Mengmeng Ma Jun Liu Kong Liu Shengchun Qu Zhi Zhao Yanjun Zhang Zhanguo Wang College of Mechanical and Electrical Engineering Handan UniversityHandan 056005China Hebei International Joint Research Center for Computational Optical Imaging and Intelligent Sensing Hebei International Joint Research Center for Computational Optical Imaging and Intelligent SensingSchool of Mathematics and Physics Science and EngineeringHebei University of EngineeringHandan 056038China Key Laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices Beijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Department of Materials Science and Engineering Faculty of Materials Science and Chemical EngineeringNingbo UniversityNingbo 315211China Faculty of Physics Adam Mickiewicz University Poznan61-614 PoznanPoland Guangdong-Hong Kong Joint Laboratory for Water Security Engineering Research Center of Ministry of Education on Groundwater Pollution Control and RemediationCenter for Water ResearchAdvanced Institute of Natural SciencesBeijing Normal University at ZhuhaiZhuhai 519087China

Developing low-cost,efficient,and stable photocatalysts is one of the most promising methods for large-scale solar water *** a metal-free semiconductor material with suitable band gap,graphitic carbon nitride(g-C_(3)N_(4))has attracted attention in the field of photocatalysis,which is mainly attributed to its fascinating physicochemical and photoelectronic ***,several inherent limitations and shortcomings—involving high recombination rate of photocarriers,insufficient reaction kinetics,and optical absorption—impede the practical applicability of g-C_(3)N_(4).As an effective strategy,vacancy defect engineering has been widely used for breaking through the current limitations,considering its ability to optimize the electronic structure and surface morphology of g-C_(3)N_(4) to obtain the desired photocatalytic *** review summarizes the recent progress of vacancy defect engineered g-C_(3)N_(4) for solar water *** fundamentals of solar water splitting with g-C_(3)N_(4) are discussed *** then focus on the fabrication strategies and effect of vacancy generated in g-C_(3)N_(4).The advances of vacancy-modified g-C_(3)N_(4) photocatalysts toward solar water splitting are discussed ***,the current challenges and future opportunities of vacancy-modified g-C_(3)N_(4) are *** review aims to provide a theoretical basis and guidance for future research on the design and development of highly efficient defective g-C_(3)N_(4).

关键词： g-C_(3)N_(4) vacancy defect water splitting photocatalyst charge carrier

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Kinetic modelling and reactivity of liquid nitromethane under detonation conditions

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Communications Chemistry 2025年第1期8卷 1-15页

作者： Teng Zhang Lang Chen Kun Yang Bin Zhang Tuo Yang Jianying Lu Danyang Liu Yao Long Jun Chen Beijing Institute of Technology Beijing China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing China HEDPS Center for Applied Physics and Technology and College of Engineering Peking University Beijing China

Liquid nitromethane (NM) may undergo detonation under accidental stimuli, making kinetic modeling crucial for assessing the safety risks associated with its detonation. This study employs first-principles molecular dynamics to investigate chemical behavior of nitromethane under high temperature (>2000 K) and pressure (>1 GPa) conditions, revealing five previously unidentified intermediates (CH3NO2H, CH2NO2H, CH2NOH, CH2ONO2, NOCH2NO2) and establishing a nitromethane chemical kinetic model which include 543 elementary reactions and 79 species, which is successfully applied in the prediction of nitromethane detonation characteristics. The calculated detonation pressure (13.5 GPa) and reaction zone time (46 ns) are in agreement with the experimental values (11.5–12.0 GPa; 50–53 ns). We also uncover the delayed response mechanism in pure nitromethane detonation. The major pollutants, many CO (34.8%), and small amount of NH3(1.7%), HCN (1.0%), etc. in nitromethane detonation products are found. These findings advance the fundamental understanding of nitromethane’s detonation reaction kinetics.

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Temporary and spatially resolved luminescence studies of p-GaN segments fabricated by vacancy-guided redistribution of Mg using sequential ion implantation of Mg and N 21

Temporary and spatially resolved luminescence studies of p-G...

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21st International Workshop on Junction Technology, IWJT 2023

作者： Shima, K. Tanaka, R. Takashima, S. Ueno, K. Edo, M. Uedono, A. Ishibashi, S. Chichibu, S.F. Tohoku University Institute of Multidisciplinary Research for Advanced Materials Sendai980-8577 Japan Advanced Technology Laboratory Fuji Electric Co. Ltd Hino191-8502 Japan University of Tsukuba Division of Applied Physics Faculty of Pure and Applied Sciences Tsukuba305-8573 Japan Research Center for Computational Design of Advanced Functional Materials National Institute of Advanced Industrial Science and Technology Tsukuba305-8568 Japan

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Thermoelastic properties of bridgmanite using deep-potential molecular dynamics

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Physical Review B 2024年第9期109卷 094101-094101页

作者： Tianqi Wan Chenxing Luo Yang Sun Renata M. Wentzcovitch Department of Applied Physics and Applied Mathematics Columbia University New York New York 10027 USA Department of Physics Xiamen University Xiamen 361005 China Department of Physics Iowa State University Ames Iowa 50011 USA Department of Earth and Environmental Sciences Columbia University New York New York 10027 USA Lamont–Doherty Earth Observatory Columbia University Palisades New York 10964 USA Data Science Institute Columbia University New York New York 10027 USA Center for Computational Quantum Physics Flatiron Institute New York New York 10010 USA

The high-pressure Pbnm-perovskite polymorph of MgSiO3, i.e., bridgmanite (Bm), plays a crucial role in the Earth's lower mantle. It is likely responsible for ∼75 vol. % of this region and its properties dominate the properties of this region, especially its elastic properties that are challenging to measure at ambient conditions. This study combines deep-learning potential (DP) with density-functional theory (DFT) to investigate the structural and elastic properties of Bm under lower-mantle conditions. To simulate this system, we developed a series of potentials capable of faithfully reproducing DFT calculations using different functionals, i.e., local density approximation (LDA), Perdew-Burke-Ernzerhof parametrization (PBE), revised PBE for solids (PBEsol), and strongly constrained and appropriately normed (SCAN) meta–generalized-gradient approximation functionals. Our predictions with DP-SCAN exhibit a remarkable agreement with experimental measurements of high-temperature equations of states and elastic properties and highlight its superior performance, closely followed by DP-LDA in accurately predicting. This hybrid computational approach offers a solution to the accuracy-efficiency dilemma in obtaining precise elastic properties at high pressure and temperature conditions for minerals like Bm, opening a way to study the Earth material's thermodynamic properties and related phenomena.

关键词： Elasticity Pressure effects Minerals Deep learning First-principles calculations Molecular dynamics

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Streamline Tracing Visualization of Flow on Curved Surfaces from Cad Models

SSRN

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SSRN 2022年

作者： Wu, Fukun Cao, Yi Dong, Qingli Institute of Applied Physics and Computational Mathematics Beijing China CAEP Software Center for High Performance Numerical Simulation Beijing China

We introduce a novel surface streamline generation algorithm for vector fields defined on curved surfaces and arbitrary manifolds. This algorithm performs the intersection calculation on curved surfaces with complex topology to achieve the highly detailed underlying vector. Then, an extended Runge-Kutta streamline integration technology is applied to perform streamline tracing on an unstructured mesh, where the adaptive stepsize strategy and intersection acceleration structure are presented for sake of simplicity and efficiency. This algorithm applies the ball feature to improve its visual intuitiveness and is integrated into the general visual analysis platform. Experimental results show that our method can generate continuous and consistent geometric surface streamlines by tracing streamlines on curved surfaces, and interactively exhibit the physical characteristics of flow on the complex geometry. © 2022, The Authors. All rights reserved.

关键词： Integration

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Bias Tunable and High Temperature Characteristics in Ratchet Detector

Bias Tunable and High Temperature Characteristics in Ratchet...

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Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSRWTC)

作者： Yi Wang Shangjie Han Jiaxuan Cai Peng Bai Ning Yang Weidong Chu Xiaohong Li Yueheng Zhang Yan Xie Meng Chen Yingxin Wang Ziran Zhao School of Information Science and Technology North China University of Technology Beijing China Institute of Applied Physics and Computational Mathematics Beijing China School of Physics and Astronomy Shanghai Jiao Tong University Shanghai China Department of Engineering Physics Tsinghua University Beijing China

The ratchet effect has promising applications in radiation detection. We propose a ratchet structure that can achieve broadband terahertz (THz) detection. In this paper, we focus on the bias-tunable characteristics of the ratchet structure and its high-temperature operating characteristics. We give the photocurrent spectrum response characteristics of the device under different bias voltages and analyze the reasons for the bias-dependent characteristics. The response photocurrent results of the device to the blackbody under different bias voltages are also analyzed. The high operating temperature characteristics of the device under zero bias are also given.

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Data-driven Discovery of Delay Differential Equations with Discrete Delays

arXiv

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arXiv 2024年

作者： Pecile, Alessandro Demo, Nicola Tezzele, Marco Rozza, Gianluigi Breda, Dimitri Mathematics Area mathLab SISSA via Bonomea 265 TriesteI-34136 Italy CDLab – Computational Dynamics Laboratory Department of Mathematics Computer Science and Physics University of Udine via delle Scienze 206 Udine33100 Italy Oden Institute for Computational Engineering and Sciences University of Texas at Austin AustinTX78712 United States

The Sparse Identification of Nonlinear Dynamics (SINDy) framework is a robust method for identifying governing equations, successfully applied to ordinary, partial, and stochastic differential equations. In this work we extend SINDy to identify delay differential equations by using an augmented library that includes delayed samples and Bayesian optimization. To identify a possibly unknown delay we minimize the reconstruction error over a set of candidates. The resulting methodology improves the overall performance by remarkably reducing the number of calls to SINDy with respect to a brute force approach. We also address a multivariate setting to identify multiple unknown delays and (non-multiplicative) parameters. Several numerical tests on delay differential equations with different long-term behavior, number of variables, delays, and parameters support the use of Bayesian optimization highlighting both the efficacy of the proposed methodology and its computational advantages. As a consequence, the class of discoverable models is significantly expanded. © 2024, CC0.

关键词： Stochastic systems

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Monte Carlo Bethe-ansatz approach for the study of the Lieb-Liniger model

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Physical Review A 2024年第3期109卷 033320-033320页

作者： Zhe-Hao Zhang Yi-Cong Yu Yang-Yang Chen Song Cheng Xi-Wen Guan Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan 430071 China University of Chinese Academy of Sciences Beijing 100049 China Institute of Modern Physics Northwest University Xi'an 710069 China Shaanxi Key Laboratory for Theoretical Physics Frontiers Xi'an 710069 China Beijing Computational Science Research Center Beijing 100193 China Department of Theoretical Physics Research School of Physics and Engineering Australian National University Canberra ACT 0200 Australia Peng Huanwu Center for Fundamental Theory Xi'an 710069 China

We have developed a Monte Carlo algorithm to explore the equilibrium and out-of-equilibrium properties of the Lieb-Liniger model. This Monte Carlo Bethe-ansatz (MCBA) algorithm has enabled us to successfully reconstruct statistical ensembles for equilibrium or postquench dynamics, thereby facilitating the calculation of macroscopic quantities of integrable models. Our results substantiate the validity of the (quench) thermodynamic Bethe-ansatz equation from the perspective of first-principles statistical physics. Additionally, we have employed this method to study the generalized Gibbs ensemble in relation to the postquench dynamics of the Lieb-Liniger model. Furthermore, we have demonstrated the MCBA algorithm's capacity to calculate correlations using Bethe-ansatz wave functions. Our approach offers an efficient methodology for the investigation of the equilibrium and out-of-equilibrium properties of integrable systems.

关键词： Bose gases 1-dimensional systems Bethe ansatz Integrable systems Monte Carlo methods

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