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入地观天——中国科学家深地窥探宇宙奥秘

Science Bulletin 2022年第2期67卷 111-113,M0003页

作者：孙扬 School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240China

The nuclear history of the Universe started shortly after the Big Bang. Through nuclear reactions, the ashes from the primordial explosion were transformed to hydrogen, helium and trace of other light elements, and to heavier products from rich variety of nucleosynthesis processes at all kinds of astrophysical sites. Many different types of reaction occur in every burning stage of stellar life.

关键词： transformed elements stellar

Spin switching in antiferromagnets using Néel-order spin-orbit torques

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Chinese physics B 2018年第10期27卷 88-95页

作者： P Wadley K W Edmonds School of Physics and Astronomy University of Nottingham

Antiferromagnets offer considerable potential for electronic device applications. This article reviews recent demonstrations of spin manipulation in antiferromagnetic devices using applied electrical currents. Due to spin–orbit coupling in environments with particular crystalline or structural symmetries, the electric current can induce an effective magnetic field with a sign that alternates on the lengthscale of the unit cell. The staggered effective field provides an efficient mechanism for switching antiferromagnetic domains and moving antiferromagnetic domain walls, with writing speeds in the terahertz regime.

关键词： spintronics antiferromagnetic current-induced torques magnetic domains

The S_(8)tension in light of updated redshift-space distortion data and PAge approximation

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Science China(physics,Mechanics & astronomy) 2022年第3期65卷 114-121页

作者： Lu Huang Zhiqi Huang Huan Zhou Zhuoyang Li School of Physics and Astronomy Sun Yat-sen UniversityZhuhai 519082China

One of the most prominent challenges to the standard Lambda cold dark matter(ΛCDM) cosmology is the tension between the structure growth parameter S;constrained by the cosmic microwave background(CMB) data and the smaller one suggested by the cosmic shear data. Recent studies show that, for ΛCDM cosmology, redshift-space distortion(RSD) data also prefers a smaller S;that is ~ 2-3σ lower than the CMB value, but the result is sensitive to the cosmological model. In the present work we update the RSD constraint on S;with the most up-to-date RSD data set where the correlation between data points is properly taken into account. To reduce the model dependence, we add in our Monte Carlo Markov Chain calculation the most up-to-date data sets of Type Ia supernovae(SN) and baryon acoustic oscillations(BAO), whose correlation with RSD is also taken into account, to constrain the background geometry. For ΛCDM cosmology we find S_(8)= 0.812 ± 0.026, which is ~ 2σ larger than previous studies, and hence is consistent with the CMB constraint. By replacing ΛCDM with the parameterization based on cosmic Age(PAge), an almost model-independent description of the late universe, we find that the RSD + SN + BAO constraint on S;is insensitive to the cosmological model.

关键词： observational cosmology large-scale structure of the Universe dark matter

Cyclic-anion salt for high-voltage stable potassium-metal batteries

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National Science Review 2022年第10期9卷 177-187页

作者： Yanyao Hu Ling Fan Apparao M.Rao Weijian Yu Caixiang Zhuoma Yanhong Feng Zhihui Qin Jiang Zhou Bingan Lu school of physics and Electronics Hunan University Department of physics and astronomy Clemson Nanomaterials Institute Clemson University school of Materials Science and Engineering Central South University

Electrolyte anions are critical for achieving high-voltage stable potassium-metal batteries(PMBs).However,the common anions cannot simultaneously prevent the formation of ’dead K’ and the corrosion of Al current collector,resulting in poor cycling stability.Here,we demonstrate cyclic anion of hexafluoropropane-1,3-disulfonimide-based electrolytes that can mitigate the ’dead K’ and remarkably enhance the high-voltage stability of PMBs.Particularly,even using low salt concentration(0.8 M) and additive-free carbonate-based electrolytes,the PMBs with a high-voltage polyanion cathode(4.4 V) also exhibit excellent cycling stability of 200 cycles with a good capacity retention of 83%.This noticeable electrochemical performance is due to the highly efficient passivation ability of the cyclic anions on both anode and cathode surfaces.This cyclic-anion-based electrolyte design strategy is also suitable for lithium and sodium-metal battery technologies.

关键词： cyclic anion low concentration additive-free electrolyte high-voltage potassium-metal batteries solid–electrolyte interface

AI empowered metasurfaces

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Light(Science & Applications) 2020年第1期9卷 1104-1107页

作者： Shuang Zhang School of Physics and Astronomy University of BirminghamBirminghamUK

Dynamic metasurfaces are endowed with self-adaptive and learning capabilities,enabling an array of important applications ranging from satellite communications to the monitoring of human health and activities.

关键词： endowed abilities meta

Surface growth approach for bulk reconstruction in the AdS/BCFT correspondence

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Chinese physics C 2024年第6期 226-235页

作者：方西浩陈方中孙佳睿 Sun Yat-Sen University School of Physics and Astronomy

In this study, we extend the surface growth approach for bulk reconstruction into the Ad S spacetime with a boundary in the Ad S/BCFT correspondence. We show that the geometry in the entanglement wedge with a boundary can be constructed from the direct growth of bulk extremal surfaces layer by layer. Furthermore, we observe that the surface growth configuration in BCFT can be connected with the defect multi scale entanglement renormalization ansatz(MERA) tensor network. Additionally, we investigate the entanglement of purification within the surface growth process, which not only reveals more refined structure of entanglement entropy in the entanglement wedge but also suggests a selection rule for surface growth in the bulk reconstruction.

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Implication from GRB 221009A:Can TeV emission come from the GRB prompt phase?

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Science China(physics,Mechanics & astronomy) 2023年第8期66卷 139-149页

作者： Kai Wang Zhi-Peng Ma Ruo-Yu Liu Yuan-Chuan Zou Zhuo Li Zi-Gao Dai Department of astronomy School of PhysicsHuazhong University of Science and TechnologyWuhan 430074China school of astronomy and Space Science Nanjing UniversityNanjing 210023China Key Laboratoryof Modern astronomy and Astrophysics Ministry of EducationNanjing UniversityNanjing 20023China Department of astronomy School of PhysicsPeking UniversityBeijing 100871China Kavli Institute for astronomy and Astrophysics Peking UniversityBeijing 100871China Department of astronomy University of Science and Technology of ChinaHefei 230026China

Recently,the B.O.A.T.(“brightest of all time”)gamma-ray burst,dubbed GRB 221009A,was detected by various instruments.Unprecedentedly,the GRB presented very-high-energy(VHE,energy above 0.1 Te V)gamma-ray emission with energy extending above 10 Te V,as reported by the Large High Altitude Air Shower Observatory(LHAASO).We here demonstrate that the VHE and especially>10 Te V emission may originate from the internal hadronic dissipation of the GRB,without the need of invoking any exotic processes as suggested by some previous studies.The possible prompt origin of LHAASO photons may imply the first detection of the GRB prompt phase in the VHE regime.We also discuss the constraints on the properties of the GRB ejecta from multiwavelength and multi-messenger observations,which favors a magnetically dominated GRB ejecta.The suggested Poynting-flux-dominated GRB ejecta in this work supports the Blandford&Znajek(BZ)mechanism as the possible central engine model of GRB,as well as the possible strong magnetic dissipation and acceleration.

关键词： cosmological neutrinos neutrino astronomy high energy astrophysics gamma-ray bursts cosmic rays

Evaluating Helium Variations By Modeling Red Giant Branch Bump of Large Magellanic Cluster NGC 1978

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Research in astronomy and Astrophysics 2022年第3期22卷 72-79页

作者： Xin Ji Cheng-Yuan Li Li-Cai Deng Key Laboratory for Optical astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China school of astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China School of Physics and Astronomy Sun Yat-sen UniversityZhuhai 519082China Department of astronomy School of Physics and AstronomyChina-West Normal UniversityNanchong 637002China

Many evidences show that the Multiple Population(MP)features exist not only in old clusters but also in intermediate-age clusters in the Megallanic Clouds(MCs),which are characterized by star-to-star abundance scatter of several elements,including helium(He).The red giant branch bump(RGBB)’s photometric properties are proved to be related to the variation in helium abundances of the member stars in star clusters.We use the"Modules for Experiments in Stellar Astrophysics"(MESA)stellar evolution code to calculate the evolution sequences of stars along the red giant branch(RGB)with changing helium content.Following the RGB sequences,we then generate a luminosity function of the RGB stars within the grid of input helium abundances,which are compared with the observational data of an intermediate-age MC cluster NGC 1978.

关键词： globular clusters:general globular clusters:individual(NGC 1978) stars:abundances stars:Hertzsprung-Russell and C-M diagrams stars:luminosity function

Experimental test of Tsirelson's bound with a single photonic qubit

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Science China(Information Sciences) 2020年第8期63卷 144-146页

作者： Zhiyu TIAN Yuan-Yuan ZHAO Hao WU Zhao WANG Le LUO School of Physics and Astronomy Sun Yat-sen University

Dear editor,For many protocols, quantum strategies have advantages compared with their classical counterpartners, and these advantages have attracted many interests and applications. One of the famous examples is the Clauser-Horne-ShimonyHolt (CHSH) game [1], which recasts Bell’s theorem [2] into the framework of a game. In the CHSH game, two space-like separated players, Alice and Bob are each assigned a classical bit a and

关键词： CHSH game quantum strategies quantum mechanics Tsirelson's bound single-photon system