Science China Physics, Mechanics & Astronomy最新文献

{"title":"Observation of tunable exceptional points in a non-Hermitian acoustic system","authors":"Chen Liu,&nbsp;Zhongming Gu,&nbsp;Haixiao Zhang,&nbsp;Xiaowei Zhang,&nbsp;Chuanhao Ge,&nbsp;Tuo Liu,&nbsp;Jie Zhu","doi":"10.1007/s11433-024-2608-4","DOIUrl":"10.1007/s11433-024-2608-4","url":null,"abstract":"<div><p>Exceptional points (EPs) have extensive and important applications in many wave-based technologies, such as ultra-sensitive sensing, unidirectional scattering and low-threshold laser. However, most of the previous EP-related wave phenomena are demonstrated in systems with fixed configuration, thereby extremely constraining their adaptability and reconfigurability in practice. Here, we introduce a flexible approach to tuning EPs in an acoustic system with sandwich structures. A rotatable component, associated with an alterable gradient index, is clamped by a pair of lossy acoustic resonators. Theoretical derivations and numerical simulations validate the capabilities of the model in continuously regulating EPs in the parameter space, with ingenious experimental setups confirming these findings. The results showcase the system’s effectiveness in achieving unidirectional reflectionless wave propagation across various frequencies. Our research reveals a flexible approach to linking the adjustment of EPs to a simple structural parameter, offering a robust framework for exploring and implementing non-Hermitian wave phenomena in practical scenarios.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 5","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143594690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extraction of energy from a black hole in Einstein-Maxwell-scalar theory","authors":"Cheng-Yong Zhang,&nbsp;Zehong Zhang,&nbsp;Ruifeng Zheng","doi":"10.1007/s11433-024-2607-1","DOIUrl":"10.1007/s11433-024-2607-1","url":null,"abstract":"<div><p>Recently, it has been discovered that the nonlinear self-interaction of matter can induce energy extraction from black holes beyond superradiant instability. This process is closely associated with the occurrence of a dynamical first-order transition between different types of static black holes. To explore whether first-order phase transitions invariably lead to energy extraction, we have investigated the evolution of black holes in the Einstein-Maxwell-scalar model with a higher-order coupling. In this model, there are also dynamical first-order phase transitions between black hole solutions. Our findings indicate that energy can only be extracted from a small, stable hairy black hole in this model. However, this energy extraction is more closely related to the growth of the black hole horizon radius, rather than the dynamical transition between different types of black holes. This suggests that a dynamical first-order phase transition does not necessarily result in energy extraction.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 5","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143594691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pressure-induced nano-crystallization and high hardness of optically transparent α-Si3N4 ceramics","authors":"Shuailing Ma,&nbsp;Wei Li,&nbsp;Xiaoqi Zhang,&nbsp;Kathy Lu,&nbsp;Min Lian,&nbsp;Xinmiao Wei,&nbsp;Yilong Pan,&nbsp;Hai Jiang,&nbsp;Hongwei Wang,&nbsp;Zihan Zhang,&nbsp;Qiang Tao,&nbsp;Tian Cui,&nbsp;Ralf Riedel,&nbsp;Pinwen Zhu","doi":"10.1007/s11433-024-2613-4","DOIUrl":"10.1007/s11433-024-2613-4","url":null,"abstract":"<div><p>Transparent silicon nitride ceramics with good optical and mechanical properties are promising ceramics for scientific and industrial window materials with a long service life. The optical transparency and mechanical strength will be substantially enhanced in dense nano-polycrystalline monoliths. However, the synthesis of nano-polycrystalline α-Si₃N₄ has not been realized due to the limitations of conventional sintering techniques. Here, nano-polycrystalline α-Si₃N₄ was prepared by direct conversion of micron-grain silicon nitride without additives under high-pressure conditions of 5 GPa and a limited temperature range 1650°C–1700°C. The micron-sized grains undergo grain refinement and recrystallization to form uniform nano-grains under high pressure and high temperature. Furthermore, transparent α-Si₃N₄ samples exhibit the highest Vickers hardness of 26.7 GPa, which is far higher than that of specimens with or without additives used in other sintering methods (e.g., SPS, and HP). According to the Hall-Petch and Taylor dislocation hardening effects, the refined nano-grains, coherent grain boundaries, and high dislocation density lead to high hardness. Moreover, the high density, nanoscale grains, and fine grain boundaries are ascribed to the improvement of transparency. Ultrahigh-pressure sintering induces grain refinement, grain coherency, and increased dislocation in silicon nitrides, thus providing a promising method for preparing advanced transparent ceramic windows in the future.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 5","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143570899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Center-of-mass magnomechanics beyond magnetostrictive limits","authors":"Hao Xiong","doi":"10.1007/s11433-024-2606-4","DOIUrl":"10.1007/s11433-024-2606-4","url":null,"abstract":"<div><p>Cavity magnomechanics, leveraging magnetostrictive interactions, has emerged as an important platform for implementing spin-based precision measurement and investigating macroscopic quantum phenomena. Due to the weakness of the intrinsic magnetostrictive effect, the coupling between magnetic and mechanical vibrations in typical magnomechanical systems is relatively small. Here, we develop a center-of-mass magnomechanical system that is non-reliant on magnetostrictive effects. The proposed system consists of an inhomogeneous magnetic field and a yttrium iron garnet (YIG) sphere that is harmonically confined. We theoretically investigate the interaction between center-of-mass motion and magnonic excitation of the YIG sphere, and find that the field inhomogeneity induces a static force on the YIG sphere. Consequently, a magnomechanical interaction between the center-of-mass motion and the magnonic excitation is established. The parameter optimization of the magnomechanical interaction has been performed, and we show that the proposed system has the potential to reside in both the single-magnon high-cooperativity regime and the sideband-resolved regime. The capabilities of the system for magnomechanical applications, such as ground-state cooling of the mechanical mode, have been discussed, and we show that ground-state cooling of the mechanical mode is feasible in the unresolved sideband regime by taking into account the magnonics Kerr effect. Our analysis holds great promise for achieving magnonic nonlinearity at low excitation levels, thereby opening up avenues for magnomechanical applications in precision measurements and quantum manipulation.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 5","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143570926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Generating arrays of perfect vector vortex beam with six on-demand degrees of freedom in metasurfaces","authors":"Changda Zhou,&nbsp;Yaqin Zheng,&nbsp;Guoli He,&nbsp;Siyang Li,&nbsp;Yanhui Deng,&nbsp;Houjiao Zhang,&nbsp;Zhang-Kai Zhou","doi":"10.1007/s11433-024-2609-9","DOIUrl":"10.1007/s11433-024-2609-9","url":null,"abstract":"<div><p>Perfect vector vortex beams (PVVBs) possess various degrees of freedom (DoFs) for optical information applications, benefiting from increasing information capacity, processing speed, etc. During the last two decades, various methods have been proposed for generating and controlling PVVBs, but most of these methods can only manipulate two or three DoFs, greatly hindering further exploration and application of PVVBs. To overcome this problem, we propose an attenuation-controlled holographic technique based on metasurfaces, which can realize the arbitrary and independent control of 6-DoFs, greatly improving the manipulation dimension of PVVBs. The PVVBs with 6 on-demand DoFs can appear in the array forms of either concentric or matrix rings without cross-talks or number limitations, which notably enlarges the number of information channels that can be simultaneously employed. Furthermore, we introduce a multi-dimensional dynamic addressing strategy for optical encryption with the advantages of both large capacity and high security due to its theoretically infinite code space. Our findings can not only deepen the study of optical field manipulation at the nanoscale, but also expand the application of structural light, promoting their utilization across the fields of nanophotonics, integrated optics, and optical information science at the high-dimensional level.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 5","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143533240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cosmological distance forecasts for the CSST Galaxy Survey using BAO peaks","authors":"Feng Shi,&nbsp;Jieyi Tian,&nbsp;Zhejie Ding,&nbsp;Xiaohu Yang,&nbsp;Yizhou Gu,&nbsp;Christoph Saulder,&nbsp;Xiaoping Li,&nbsp;Yanming Liu,&nbsp;Zitong Wang,&nbsp;Hu Zhan,&nbsp;Ming Li,&nbsp;Xiaolei Li,&nbsp;Hong Guo,&nbsp;Yan Gong,&nbsp;Yunkun Han,&nbsp;Cheng Li,&nbsp;Yipeng Jing,&nbsp;Jipeng Sui,&nbsp;Run Wen,&nbsp;Gong-Bo Zhao,&nbsp;Hu Zou,&nbsp;Pengjie Zhang,&nbsp;Xianzhong Zheng,&nbsp;Xingchen Zhou","doi":"10.1007/s11433-024-2603-8","DOIUrl":"10.1007/s11433-024-2603-8","url":null,"abstract":"<div><p>The measurement of cosmological distances using baryon acoustic oscillations (BAO) is crucial for studying the universe’s expansion. The China Space Station Telescope (CSST) galaxy redshift survey, with its vast volume and sky coverage, provides an opportunity to address key challenges in cosmology. However, redshift uncertainties in galaxy surveys can degrade both angular and radial distance estimates. In this study, we forecast the precision of BAO distance measurements using mock CSST galaxy samples, applying a two-point correlation function (2PCF) wedge approach to mitigate redshift errors. We simulate redshift uncertainties of <i>σ</i>₀ = 0.003 and <i>σ</i>₀ = 0.006, representative of expected CSST errors, and examine their effects on the BAO peak and distance scaling factors, <i>α</i>_⊥ and <i>α</i>_∥, across redshift bins within 0.0 &lt; <i>z</i> ⩽ 1.0. The wedge 2PCF method proves more effective in detecting the BAO peak compared with the monopole 2PCF, particularly for <i>σ</i>₀ = 0.006. Constraints on the BAO peaks show that <i>α</i>_⊥ is well constrained around 1.0, regardless of <i>σ</i>₀, with precision between 1% and 3% across redshift bins. In contrast, <i>α</i>_∥ measurements are more sensitive to increases in <i>σ</i>₀. For <i>σ</i>₀ = 0.003, the results remain close to the fiducial value, with uncertainties ranging between 4% and 9%; for <i>σ</i>₀ = 0.006, significant deviations from the fiducial value are observed. We also study the ability to measure parameters (Ω_<i>m</i>, <i>H</i>₀<i>r</i>_d) using distance measurements, proving robust constraints as a cosmological probe under CSST-like redshift uncertainties. These findings demonstrate that the CSST survey enables few-percent precision measurements of <i>D</i>_<i>A</i> using the wedge 2PCF method, highlighting its potential to place tight constraints on the universe’s expansion history and contribute to high-precision cosmological studies.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 4","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143553772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preformed Cooper pairs in a triclinic iron pnictide superconductor","authors":"Zezhong Li,&nbsp;Wenshan Hong,&nbsp;Honglin Zhou,&nbsp;Xiaoyan Ma,&nbsp;Uwe Stuhr,&nbsp;Kaiyue Zeng,&nbsp;Long Ma,&nbsp;Ying Xiang,&nbsp;Huan Yang,&nbsp;Hai-Hu Wen,&nbsp;Jiangping Hu,&nbsp;Shiliang Li,&nbsp;Huiqian Luo","doi":"10.1007/s11433-024-2596-6","DOIUrl":"10.1007/s11433-024-2596-6","url":null,"abstract":"<div><p>Electron pairing along with phase coherence generates superconductivity below the critical temperature (<i>T</i>_<i>c</i>). In underdoped high-<i>T</i>_<i>c</i> cuprates, these two quantum phenomena may occur at separate temperatures, which was lately confirmed in the quasi-two-dimensional (quasi-2D) iron chalcogenide superconductors. Here, we report a systematic investigation on the pre-pairing behavior in a triclinic iron pnictide superconductor (Ca_0.85La_0.15)₁₀(Pt₃As₈)(Fe₂As₂)₅ with <i>T</i>_<i>c</i> ≈ 30 K, where the superconductivity is quasi-2D manifested by the Berezinskii-Kosterlitz-Thouless behaviors. Inelastic neutron scattering experiments unambiguously reveal a spin resonance peak around <i>E</i>_<i>R</i> = 13 meV in the superconducting state, but its intensity continuously decreases when warming up across <i>T</i>_<i>c</i>, accompanied with an anomaly around <i>T</i>* ≈ 45 K in spin correlations, and a suppression by an in-plane magnetic field persisting to the same temperature. Below <i>T</i>*, a significant Nernst signal and a reduction of density of states at the Fermi level are also observed. These results suggest that the precursor of spin resonance is highly related to the preformed Cooper pairs driven by phase fluctuations, much like the pseudogap case in cuprates.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 4","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Superradiant growth anomaly magnification in evolution of vector bosonic condensates bounded by a Kerr black hole with near-horizon reflection","authors":"Nayun Jia,&nbsp;Yin-Da Guo,&nbsp;Gui-Rong Liang,&nbsp;Zhan-Feng Mai,&nbsp;Xin Zhang","doi":"10.1007/s11433-024-2602-0","DOIUrl":"10.1007/s11433-024-2602-0","url":null,"abstract":"<div><p>Ultralight vector particles can form evolving condensates around a Kerr black hole (BH) due to superradiant instability. We study the effect of near-horizon reflection on the evolution of this system: by matching three pieces of asymptotic expansions of the Proca equation in Kerr metric and considering the leading order in the electric mode, we present explicit analytical expressions for the corrected spectrum and the superradiant instability rates. Particularly, in high-spin BH cases, we identify an anomalous situation where the superradiance rate is temporarily increased by the reflection parameter <i>ℛ</i>, which also occurs in the scalar scenario, but is largely magnified in vector condensates due to a faster growth rate in dominant mode. We point out that the condition for the growth anomaly in the adiabatic case is that information carried per particle exceeds a certain value <span>(delta I/delta N &gt;2pi k_{mathrm{B}}sqrt{(1+mathcal{R})/(1-mathcal{R})})</span>. We further construct several featured quantities to illustrate it, and formalize the anomaly-induced gravitational wave strain deformation.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 4","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spin magnetization in unconventional antiferromagnets with collinear and non-collinear spins","authors":"Lun-Hui Hu,&nbsp;Song-Bo Zhang","doi":"10.1007/s11433-024-2567-6","DOIUrl":"10.1007/s11433-024-2567-6","url":null,"abstract":"<div><p>Unconventional antiferromagnets (AFMs) with non-relativistic spin-splitting, such as the recently discovered altermagnet, have recently gained significant interest due to their potential for novel quantum phenomena and spintronic applications. The compensated magnetization in unconventional AFMs is protected by spin-space symmetries. In this work, we explore the symmetry-breaking effects and identify three distinct mechanisms for inducing net spin magnetizations in unconventional AFMs with collinear or non-collinear spins: (1) finite size effect, (2) extrinsic spin canting effect, and (3) irradiation with circularly polarized light. We show that the induced spin magnetizations are controllable and manifest as diverse intriguing phenomena. For the finite size system, the confined direction of a two-dimensional AM creates quantum-well-like subbands that determine the spin magnetization. This effect can be experimentally probed by measuring the spin density of states and the spin-polarization of Andreev-bound states within planar Josephson junctions. In the case of spin canting effect, it leads to peculiar anisotropic and non-monotonic behaviors in the superconducting proximity effect. Lastly, with circularly polarized light, spin magnetization is driven by the polarized light and the chirality of non-collinear magnetic order, thus offering a direct means of detecting the chirality of magnetic order in real materials. Our findings provide valuable insight into understanding and probing the spin magnetization in unconventional AFM materials.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 4","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143466046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A fully mesh-independent non-linear topology optimization framework based on neural representations: Quasi-static problem","authors":"Zeyu Zhang,&nbsp;Yu Li,&nbsp;Weien Zhou,&nbsp;Wen Yao","doi":"10.1007/s11433-024-2576-7","DOIUrl":"10.1007/s11433-024-2576-7","url":null,"abstract":"<div><p>In artificial intelligence (AI) for science, the AI-empowered topology optimization methods have garnered sustained attention from researchers and achieved significant development. In this paper, we introduce the implicit neural representation (INR) from AI and the material point method (MPM) from the field of computational mechanics into topology optimization, resulting in a novel differentiable and fully mesh-independent topology optimization framework named MI-TONR, and it is then applied to nonlinear topology optimization (NTO) design. Within MI-TONR, the INR is combined with the topology description function to construct the design model, while implicit MPM is employed for physical response analysis. A skillful integration is achieved between the design model based on the continuous implicit representation field and the analysis model based on the Lagrangian particles. Along with updating parameters of the neural network (i.e., design variables), the structural topologies iteratively evolve according to the responses analysis results and optimization functions. The computational differentiability is ensured at every step of MI-TONR, enabling sensitivity analysis using automatic differentiation. In addition, we introduce the augmented Lagrangian Method to handle multiple constraints in topology optimization and adopt a learning rate adaptive adjustment scheme to enhance the robustness of the optimization process. Numerical examples demonstrate that MI-TONR can effectively conduct NTO design under large loads without any numerical techniques to mitigate numerical instabilities. Meanwhile, its natural satisfaction with the no-penetration condition facilitates the NTO design of considering contact. The infinite spatial resolution characteristic facilitates the generation of structural topology at multiple resolutions with clear and continuous boundaries.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 4","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143466048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}