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H?rmander oscillatory integral operators: A revisit

Science China mathematics 2025年第4期 873-890页

作者： Chuanwei Gao Zhong Gao Changxing Miao School of Mathematical Sciences Capital Normal University Institute of Applied Physics and Computational Mathematics

In this paper, we present new proofs for both the sharp Lpestimate and the decoupling theorem for the H?rmander oscillatory integral operator. The sharp Lpestimate was previously obtained by Stein（1986） and Bourgain and Guth（2011） via the TT*and multilinear methods, respectively. We provide a unified proof based on the bilinear method for both odd and even dimensions. The strategy is inspired by Barron's work（2022） on the restriction problem. The decoupling theorem for the H?rmander oscillatory integral operator can be obtained by the approach in Beltran et al.（2020）, where the key observation can be roughly formulated as follows: in a physical space of sufficiently small scale, the variable setting can be essentially viewed as *** contrast, we reprove the decoupling theorem for the H?rmander oscillatory integral operator through the Pramanik-Seeger approximation approach(Pramanik and Seeger（2007）). Both proofs rely on a scale-dependent induction argument, which can be used to deal with perturbation terms in the phase function.

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Highly excited quantum state-selective capture dynamics in slow Ar8+−H2 collisions

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Physical Review A 2024年第3期109卷 032819-032819页

作者： Md Abul Kalam Azad Siddiki G. P. Zhao L. Liu Deepankar Misra Department of Nuclear and Atomic Physics Tata Institute of Fundamental Research Homi Bhabha Road Colaba Mumbai 400005 India College of Data Science Jiaxing University Jiaxing 314001 China Data Center for High Energy Density Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China

We report on the combined experimental and theoretical studies of the single-electron capture collisions of Ar8+ projectiles with the H2 molecules at 1, 2, and 4 keV/u collision energies. The nondissociative recoil H2+ molecular ions are measured in coincidence with the charge-changing Ar7+ projectiles. The relative cross sections of the different state-selective capture channels are obtained from the experimentally measured Q-value spectra. The 1s electron transfers to the highly excited 4d+4f, 5s, 5p, 5d+5f+5g, 6s+6p, and 6d+6f+6g+6h states are resolved experimentally. The differential scattering angle distributions for the dominant 1s to 5s, 5p, and 5d+5f+5g transitions are compared with the two-center atomic orbital close-coupling methods. A collision energy-dependent dynamical coupling effect is also observed for the 1s→5p0 and 1s→5p±1 transitions. The dominant oscillatory structures in the scattering-angle distributions are attributed to Stueckelberg-type oscillations. In contrast, the less visible undulations in the smaller scattering angles imprint the signature of the quantum matter-wave scattering of the projectiles. The quantum nature of the oscillations in the angular distributions is further validated by classical calculations. Our study thus illustrates the highly excited quantum state-selective electron capture process and sheds light on the scattering-angle-range-dependent collision dynamics for highly charged ion-molecule collisions in the highly perturbative regime.

关键词： Atomic & molecular collisions Scattering of atoms, molecules, clusters & ions Scattering theory

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Quadratic Finite Volume Element Schemes over Triangular Meshes for a Nonlinear Time-Fractional Rayleigh-Stokes Problem

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Computer Modeling in Engineering & Sciences 2021年第5期127卷 487-514页

作者： Yanlong Zhang Yanhui Zhou Jiming Wu Graduate School of China Academy of Engineering Physics Beijing100088China School of Data and Computer Science Sun Yat-Sen UniversityGuangzhou510275China Institute of Applied Physics and Computational Mathematics Beijing100088China

In this article,we study a 2D nonlinear time-fractional Rayleigh-Stokes problem,which has an anomalous subdiffusion term,on triangular meshes by quadratic finite volume element ***-fractional derivative,defined by Caputo fractional derivative,is discretized through L2−1σformula,and a two step scheme is used to approximate the time first-order derivative at time tn−α/2,where the nonlinear term is approximated by using a matching linearized difference scheme.A family of quadratic finite volume element schemes with two parameters are proposed for the spatial discretization,where the range of values for two parameters areβ1∈(0,1/2),β2∈(0,2/3).For testing the precision of numerical algorithms,we calculate some numerical examples which have known exact solution or unknown exact solution by several kinds of quadratic finite volume element schemes,and contrast with the results of an existing quadratic finite element scheme by drawing diversified comparison plots and showing the detailed data of L2 error results and convergence *** results indicate that,L2 error estimate of one scheme with parameters β_(1)=(3−√3)/6,β2=(6+√3−√21+6√3)/9 is O(h^(3)+△t^(2)),and L^(2) error estimates of other schemes are O(h^(2)+△t^(2)),where h and △t denote the spatial and temporal discretization parameters,respectively.

关键词： Quadratic finite volume element schemes anomalous sub-diffusion term L2 error estimate quadratic finite element scheme

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Structure function of helicity in compressible homogeneous isotropic turbulence

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Physical Review Fluids 2025年第3期10卷 034610-034610页

作者： Running Hu Zheng Yan Runyuan Gan Xinliang Li Changping Yu State Key Laboratory of High Temperature Gas Dynamics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China School of Engineering Science University of Chinese Academy of Sciences Beijing 100049 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China

Helicity plays an essential role in the interscale dynamics of turbulence. This paper focuses on the compressible effects on helicity cascades via structure functions. We first investigate the spatial-local dynamics of helicity, revealing that helicity is enhanced by pressure gradients along vorticity lines. Then, structure functions are used to describe the multiscale dynamics. The scaling law r2/3 for helicity remains valid in compressible turbulence, as helicity is independent of the compressive components. Additional pressure and divergence terms are introduced in the new third-order relation for helicity in compressible turbulence. The pressure term is related to the pressure gradients along the vorticity lines and plays a dominant role in the dissipative range. The divergence term is mainly induced by the mixed structure function of divergence and helicity, significantly contributing to inverse helicity cascades in the inertial range.

关键词： Vorticity

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Nodal points, lines, and surfaces, and topological surface states in superconductor NiBi3

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Physical Review B 2025年第9期111卷 094508-094508页

作者： Jie Zhang Kai-Yue Jiang Shu-Xiang Qiao Peng-Cheng Xiao Na Jiao Ping Zhang Hong-Yan Lu Qi-Feng Liang School of Physics and Physical Engineering Qufu Normal University Qufu 273165 China Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices High Magnetic Field Laboratory HFIPS Chinese Academy of Sciences Hefei Anhui 230031 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China Department of Physics Shaoxing University Shaoxing 312000 China

Despite the numerous reports on the time-honored superconductor NiBi3, theoretical investigations remain limited, particularly regarding the impact of spin-orbit coupling (SOC). Based on first-principles calculations, the electronic topology of NiBi3 is mainly studied herein. Nodal loops which intersect to form a nodal chain structure are enclosed by two valence bands, and they are fully gapped by SOC. The full gap contains topological surface states defined by a Z2 topological invariant, while for the top valence band and bottom conduction band, a three-dimensional massless Dirac point at Γ is produced by the two bands with SOC. In addition, nodal surfaces which prevalently appear in the band structure without SOC are present on the entire Brillouin zone surface, and SOC only partially gaps them, thus leading to nodal lines unaffected by SOC. Type-I and type-II fermions, which are distinguished by the tilt of cones, are shown to coexist in the bulk bands. Furthermore, two Rashba-split bands are found on the (100) surface, whose inner and outer Fermi circles share the same spin polarization direction. Finally, our analysis reveals that the superconductivity of NiBi3 primarily originates from the p orbitals of Bi and d orbitals of Ni coupling with the vibration modes of Bi. The rich topological features identified in this study suggest that NiBi3 holds significant potential for realizations of topological superconductivity and other exotic phenomena.

关键词： Topology

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A Predictor-Corrector Monte Carlo Method for Thermal Radiative Transfer Equations

SSRN

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SSRN 2023年

作者： Shi, Yi Xie, Hui School of Mathematics Shandong University Jinan250100 China Institute of Applied Physics and Computational Mathematics Beijing100094 China

In this paper, we develop a predictor-corrector Monte Carlo method for solving the thermal radiative transfer equations. A two-step numerical method is employed when the material temperature violates the maximum principle. A linear combination of the prediction and correction solutions is obtained as the final solution, where the coefficient is determined by solving an optimization problem. The new method is more implicit than the IMC method in that it uses a more implicit estimate for the material temperature dependent quantities. Moreover, we note that the last modification step is necessary because using the iterative solution directly may overestimate the material temperature when large time steps are used. Numerical simulations show that the new method can significantly mitigate the violation of maximum principle in comparison with the standard IMC method, and results in more accurate solutions than the original predictor-corrector method when the time step is large. © 2023, The Authors. All rights reserved.

关键词： Maximum principle

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Anomalous thermal transport across the superionic transition in ice

arXiv

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arXiv 2023年

作者： Qiu, Rong Zeng, Qiyu Wang, Han Kang, Dongdong Yu, Xiaoxiang Dai, Jiayu Department of Physics National University of Defense Technology Changsha410073 China Hunan Key Laboratory of Extreme Matter and Applications National University of Defense Technology Changsha410073 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100088 China

Superionic ices with highly mobile protons within the stable oxygen sub-lattice occupy an important proportion of the phase diagram of ice and widely exist in the interior of icy giants and throughout the universe. Understanding the thermal transport in superionic ice is vital for the thermal evolution of icy planets. However, it is highly challenging due to the extreme thermodynamic conditions and dynamical nature of protons, beyond the capability of the traditional lattice dynamics and empirical potential molecular dynamics approaches. In this work, by utilizing the deep potential molecular dynamics approach, we investigate the thermal conductivity of ice-VII and superionic ice-VII" along the isobar of p = 30 GPa. A non-monotonic trend of thermal conductivity with elevated temperature is observed. Through heat flux decomposition and trajectory-based spectra analysis, we show that the thermally-activated proton diffusion in ice-VII and superionic ice-VII" contribute significantly to heat convection, while the broadening in vibrational energy peaks and significant softening of transverse acoustic branches lead to a reduction in heat conduction. The competition between proton diffusion and phonon scattering results in anomalous thermal transport across the superionic transition in ice. This work unravels the important role of proton diffusion in the thermal transport of high-pressure ice. Our approach provides new insights into modeling the thermal transport and atomistic dynamics in superionic materials. © 2023, CC BY.

关键词： Ice

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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

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Electron charge qubit with 0.1 millisecond coherence time

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Nature physics 2024年第1期20卷 116-122页

作者： Zhou, Xianjing Li, Xinhao Chen, Qianfan Koolstra, Gerwin Yang, Ge Dizdar, Brennan Huang, Yizhong Wang, Christopher S. Han, Xu Zhang, Xufeng Schuster, David I. Jin, Dafei Center for Nanoscale Materials Argonne National Laboratory LemontIL United States Pritzker School of Molecular Engineering University of Chicago ChicagoIL United States Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA United States The NSF AI Institute for Artificial Intelligence and Fundamental Interactions CambridgeMA United States Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology CambridgeMA United States James Franck Institute and Department of Physics University of Chicago ChicagoIL United States Department of Electrical and Computer Engineering Northeastern University BostonMA United States Department of Applied Physics Stanford University StanfordCA United States Department of Physics and Astronomy University of Notre Dame Notre DameIN United States

Electron charge qubits are compelling candidates for solid-state quantum computing because of their inherent simplicity in qubit design, fabrication, control and readout. However, electron charge qubits built on conventional semiconductors and superconductors suffer from severe charge noise that limits their coherence time to the order of one microsecond. Here we report electron charge qubits that exceed this limit, based on isolated single electrons trapped on an ultraclean solid neon surface in a vacuum. Quantum information is encoded in the motional states of an electron that is strongly coupled with microwave photons in an on-chip superconducting resonator. The measured relaxation and coherence times are both on the order of 0.1 ms, surpassing all existing charge qubits and rivalling state-of-the-art superconducting transmon qubits. The simultaneous strong coupling of two qubits with a common resonator is also demonstrated, as the first step towards two-qubit entangling gates for universal quantum computing. © 2023, The Author(s), under exclusive licence to Springer Nature Limited.

关键词： Superconducting resonators

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ILL-POSEDNESS ISSUE FOR THE 2D VISCOUS SHALLOW WATER EQUATIONS IN SOME CRITICAL BESOV SPACES

arXiv

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arXiv 2022年

作者： Chen, Qionglei Nie, Yao Institute of Applied Physics and Computational Mathematics Beijing100191 China

We study the Cauchy problem of the 2D viscous shallow water equations 2 in some critical Besov spaces (Equation presented). As is known, this system is locally well-posed for large initial data as well as globally well-posed for small initial data in (Equation presented) for p 4. In this paper, we prove that this system is ill-posed for the critical case p = 4 in the sense of "norm inflation". Furthermore, we also show that the system is ill-posed in (Equation presented) for any q ≠ 2. Copyright © 2022, The Authors. All rights reserved.

关键词： Banach spaces

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