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Photoproduction reactionγn→K^(*0)∧in an effective Lagrangian approach

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Chinese Physics C 2022年第2期46卷 57-61页

作者：韦能昌朱一鸣黄飞 school of Nuclear Science and technology University of Chinese Academy of SciencesBeijing 101408China school of physical sciences University of Chinese Academy of SciencesBeijing 101408China

In our previous work[Phys.Rev.C 101,014003(2020)],the photoproduction reactionγp→K^(*+)Λwas investigated within an effective Lagrangian approach.The reaction amplitudes were constructed by including the t-channel K,K^(*),and k exchanges,u-channelΛ,∑,and∑^(*)exchanges,s-channel N,N(2000)5/2^(+),and N(2060)5/2^(-)exchanges,and interaction current.The data on the differential cross sections and spin density matrix elements were described simultaneously.In this study,we investigate the photoproduction reactionγn→K^(*0)Λbased on the same reaction mechanism as that ofγp→K^(*+)Λto obtain a unified description of the data forγp→K^(*+)Λandγn→K^(*0)Λwithin the same model.All hadronic coupling constants,form factor cutoffs,and the resonance masses and widths in the present calculations remain the same as in our previous work forγp→K^(*+)Λ.The available differential cross-section data forγn→K^(*0)Λare well reproduced.Further analysis shows that the cross sections ofγn→K^(*0)Λare dominated by the contributions of the t-channel K exchange,while the s-channel N(2000)5/2+and N(2060)5/2-exchanges also provide considerable contributions.

关键词： photoproduction effective Lagrangian approach gauge invariance

Holevo bound independent of weight matrices for estimating two parameters of a qubit

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Chinese Physics B 2024年第2期33卷 137-143页

作者：牛畅郁司夏 Department of Modern Physics&Hefei National Research Center for physical sciences at the Microscale and school of physical sciences University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China

Holevo bound plays an important role in quantum metrology as it sets the ultimate limit for multi-parameter estimations,which can be asymptotically achieved.Except for some trivial cases,the Holevo bound is implicitly defined and formulated with the help of weight matrices.Here we report the first instance of an intrinsic Holevo bound,namely,without any reference to weight matrices,in a nontrivial case.Specifically,we prove that the Holevo bound for estimating two parameters of a qubit is equivalent to the joint constraint imposed by two quantum Cramér–Rao bounds corresponding to symmetric and right logarithmic derivatives.This weightless form of Holevo bound enables us to determine the precise range of independent entries of the mean-square error matrix,i.e.,two variances and one covariance that quantify the precisions of the estimation,as illustrated by different estimation models.Our result sheds some new light on the relations between the Holevo bound and quantum Cramer–Rao bounds.Possible generalizations are discussed.

关键词： quantum metrology quantum Fisher information Holevo bound quantum multi-parameter estimation

Control Protocol of Finite Dimensional Quantum Systems

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Communications in Theoretical Physics 2013年第12期60卷 731-737页

作者：唐剑炬付洪忱 School of Physical Sciences and Technology Shenzhen University

An analytic control protocol of two types of finite dimensional quantum systems is proposed. The system can be driven to an arbitrary target state using cosine classical fields in finite cycles. The control parameters which are time periods of interaction between systems and control fields in each cycle are connected with the probability amplitudes of target states via trigonometrical functions and can be determined analytically.

关键词：量子系统控制协议有限维目标状态周期控制控制参数函数连接交互系统

Magnetic proximity effect in the two-dimensional ε-Fe_(2)O_(3)/NbSe_(2)heterojunction

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Chinese Physics B 2024年第2期33卷 492-497页

作者：车冰玉胡国静朱超郭辉吕森浩刘轩冶吴康赵振潘禄禄祝轲齐琦韩烨超林晓李子安申承民鲍丽宏刘政周家东杨海涛高鸿钧 Beijing National Center for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China school of physical sciences University of Chinese Academy of SciencesBeijing 100190China school of Materials Science and Engineering Nanyang Technological UniversitySingapore school of physical Science and technology Guangxi UniversityGuangxi 530004China school of Physics Beijing Institute of TechnologyBeijing 100081China

Two-dimensional(2D)magnet/superconductor heterostructures can promote the design of artificial materials for exploring 2D physics and device applications by exotic proximity effects.However,plagued by the low Curie temperature and instability in air,it is hard to realize practical applications for the reported layered magnetic materials at present.In this paper,we developed a space-confined chemical vapor deposition method to synthesize ultrathin air-stable ε-Fe_(2)O_(3) nanosheets with Curie temperature above 350 K.The ε-Fe_(2)O_(3)/NbSe_(2) heterojunction was constructed to study the magnetic proximity effect on the superconductivity of the NbSe_(2) multilayer.The electrical transport results show that the subtle proximity effect can modulate the interfacial spin–orbit interaction while undegrading the superconducting critical parameters.Our work paves the way to construct 2D heterojunctions with ultrathin nonlayered materials and layered van der Waals(vdW)materials for exploring new physical phenomena.

关键词： two-dimensional heterojunctions magnetic proximity effect non-layered magnetic nanosheet spin-orbit interaction

Global Strong Solutions and Large-time Behavior of 2D Tropical Climate Model

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应用数学学报:英文版 2023年第4期39卷 886-925页

作者： Dong-juan NIU Ying WANG school of Mathematical sciences Capital Normal UniversityBeijing 100048China school of physical Science and technology Guangxi UniversityNanning 530004China

In this paper we mainly deal with the global well-posedness and large-time behavior of the 2D tropical climate model with small initial data. We first establish the global well-posedness of solution in the Besov space, then we obtain the optimal decay rates of solutions by virtue of the frequency decomposition method. Specifically, for the low frequency part, we use the Fourier splitting method of Schonbek and the spectrum analysis method, and for the high frequency part, we use the global energy estimate and the behavior of exponentially decay operator.

关键词： tropical climate model large-time behavior global well-posedness

Forecasting the spread of the COVID-19 pandemic in Kenya using SEIR and ARIMA models

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Infectious Disease Modelling 2022年第2期7卷 179-188页

作者： Joyce Kiarie Samuel Mwalili Rachel Mbogo Institute of Mathematical sciences Strathmore UniversityNairobiKenya school of Mathematical and physical sciences Jomo Kenyatta University of Agriculture and TechnologyNairobiKenya

COVID-19,a coronavirus disease 2019,is an ongoing pandemic caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).The first case in Kenya was identified on March 13,2020,with the pandemic increasing to about 237,000 confirmed cases and 4,746 deaths by August 2021.We developed an SEIR model forecasting the COVID-19 pandemic in Kenya using an Autoregressive Integrated moving averages(ARIMA)model.The average time difference between the peaks of wave 1 to wave 4 was observed to be about 130 days.The 4th wave was observed to have had the least number of daily cases at the peak.According to the forecasts made for the next 60 days,the pandemic is expected to continue for a while.The 4th wave peaked on August 26,2021(498th day).By October 26,2021(60th day),the average number of daily infections will be 454 new cases and 40 severe cases,which would require hospitalization,and 16 critically ill cases requiring intensive care unit services.The findings of this study are key in developing informed mitigation strategies to ensure that the pandemic is contained and inform the preparedness of policymakers and health care workers.

关键词： ARIMA COVID-19 Infectious disease model Forecasting SEIR Kenya pandemic

Non-associative learning behavior in mixed proton and electron conductor hybrid pseudo-diode

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维普期刊数据库

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Journal of Materials Science & technology 2023年第29期160卷 204-213页

作者： Zhi Wen Shi Wei Sheng Wang Ling Ai Yan Li Xin Li Chen Hui Xiao Yu Heng Zeng Li Qiang Zhu school of physical Science and technology Ningbo UniversityNingbo 315211China Ningbo Institute of Materials technology and Engineering Chinese Academy of SciencesNingbo 315201China

With inherent ionic priorities, mixed ion and electron conductor hybrid devices have been proposed for brain-inspired neuromorphic system applications, demonstrating interesting neuromorphic functions. Here, mixed proton and electron conductor (MPEC) hybrid oxide neuromorphic transistor is proposed by adopting aqueous solution-processed mesoporous silica coating (MSC)-based electrolyte as gate dielec- tric. With optical and electrical synergetic coupling behaviors, the device demonstrates typical synap- tic responses and transition between short-term plasticity and long-term plasticity. With unique field- configurable proton self-modulation behaviors, a pseudo-diode operation mode is demonstrated on the MPEC hybrid transistor. Moreover, the device demonstrates interesting non-associative learning, including habituation and sensitization behavior. The results show that the proposed MPEC hybrid oxide neuromor- phic transistor has great potential in the field of neuromorphic engineering and would have potential in the bionic visual perception platform .

关键词： Mixed proton and electron conductor hybrid Oxide neuromorphic transistors Non-associative learning Pseudo-diode

Classifying coke using CT scans and landmark multidimensional scaling

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维普期刊数据库

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International Journal of Coal Science & technology 2023年第1期10卷 160-172页

作者： Keith Nesbitt Fayeem Aziz Merrick Mahoney Stephan Chalup Bishnu P.Lamichhane school of Information and physical sciences Universityof NewcastleCallaghanNSWAustralia

One factor that limits development of fundamental research on the infuence of coke microstructure on its strength is the difculty in quantifying the way that microstructure is both classifed and distributed in three dimensions.To support such fundamental studies,this study evaluated a novel volumetric approach for classifying small(approx.450μm^(3))blocks of coke microstructure from 3D computed tomography scans.An automated process for classifying microstructure blocks was described.It is based on Landmark Multi-Dimensional Scaling and uses the Bhattacharyya metric and k-means clustering.The approach was evaluated using 27 coke samples across a range of coke with diferent properties and reliably identifed 6 ordered class of coke microstructure based on the distribution of voxel intensities associated with structural density.The lower class(1–2)subblocks tend to be dominated by pores and thin walls.Typically,there is an increase in wall thickness and reduced pore sizes in the higher classes.Inert features are also likely to be seen in higher classes(5–6).In general,this approach provides an efcient automated means for identifying the 3D spatial distribution of microstructure in CT scans of coke.

关键词： Coke Microstructure Clustering Classifcation Computer tomography

The modification toward excited-state dynamics and catalytic activity by isomeric Au_(44)clusters

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维普期刊数据库

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Nano Research 2023年第8期16卷 11383-11388页

作者： Tongxin Song Jie Kong Shisi Tang Xiao Cai Xu Liu Meng Zhou Wen Wu Xu Weiping Ding Yan Zhu school of Chemistry and Chemical Engineering Nanjing UniversityNanjing 210093China Hefei National Research Center for physical sciences at the Microscale University of Science and Technology of ChinaHefei 230026China school of physical Science and technology Ningbo UniversityNingbo 315211China

The structure determination of metal nanoclusters protected by ligands is critical in understanding their physical and chemical properties,yet it remains elusive how the metal core and ligand of metal clusters cooperatively contribute to the observed performances.Here,with the successful synthesis of Au_(44)TBPA_(22)Cl_(2)cluster(TBPA=4-tert-butylphenylacetylene),the structural isomer of previously reported Au_(44)L_(28)clusters(L denoted as ligand)is filled,thereby providing an opportunity to explore the property evolution rules imparted by different metal core structures or different surface ligands.Time-resolved transient absorption spectroscopy reveals that the difference in the core structure between Au_(44)TBPA_(22)Cl_(2)and Au_(44)L_(28)can bring nearly 360 times variation of excited-state lifetime,while only 3–24 times differences in excited-state lifetimes of the three Au_(44)L_(28)nanoclusters with identical metal core but different ligands are observed,which is due to much stronger impact of the metal core than the surface ligands in the electronic energy bands of the clusters.In addition,the Au_(44)clusters protected by alkyne ligands are shown to be highly effective toward the electrochemical oxidation of ethanol,compared to the Au_(44)clusters capped by thiolates,which is ascribed to smaller charge transfer impedance of the former clusters.We anticipate that the study will enhance the process in controlling the nanomaterial properties by precisely tailoring metal core or surface patterns.

关键词： cluster metal core surface ligand excited-state dynamics catalysis