Science China Physics, Mechanics & Astronomy最新文献

{"title":"On-chip multidimensional (de)multiplexer utilizing adiabatic structure-connected micro-ring resonators","authors":"Zhiwei Guan,&nbsp;Keyin Wen,&nbsp;Chuangxin Xie,&nbsp;Ruixue Dou,&nbsp;Tianyimei Zuo,&nbsp;Junmin Liu,&nbsp;Huapeng Ye,&nbsp;Chaofeng Wang,&nbsp;Ze Dong,&nbsp;Dianyuan Fan,&nbsp;Shuqing Chen","doi":"10.1007/s11433-024-2605-3","DOIUrl":"10.1007/s11433-024-2605-3","url":null,"abstract":"<div><p>On-chip multidimensional multiplexing has shown considerable potential for enhancing transmission capacity and developing communication networks in integrated optical systems. Micro-ring resonators, which utilize the wavelength-dependent whispering gallery resonance mechanism and feature customizable cavity lengths, offer inherent advantages for accurate wavelength filtering. These characteristics make them promising candidates for wavelength multiplexers. However, a significant challenge arises from the mismatch in the effective refractive index between orthogonal linear polarizations, which introduces complexities to polarization channel multiplexing and impedes progress in on-chip multidimensional multiplexing that integrates both wavelength and polarization channels. In this work, we propose a double-layer adiabatic structure-connected micro-ring resonator (AMRR) with vertical refractive index asymmetry, demonstrating its utility in multidimensional (de)multiplexers. Our approach enables polarization division multiplexing (PDM) by facilitating polarization rotation between transverse electric and transverse magnetic polarizations through polarization hybridization. The (de)multiplexing of both wavelength and polarization channels is achieved by controlling the incident light direction and filtering the resonance wavelength within the micro-ring resonator. As a proof of concept, we successfully transmitted 144 Gbit/s QPSK-OFDM signals and achieved bit error rates below the forward error correction threshold at −19 dBm using the proposed multidimensional (de)multiplexer, which accommodates 3 wavelengths and 2 polarizations. Our design, which leverages the AMRR for simultaneous (de)multiplexing of wavelength and polarization channels, not only overcomes the limitation of traditional micro-ring resonators in implementing PDM, but also reduces the footprint of the multidimensional (de)multiplexer to 27 µm × 219 µm, an order of magnitude smaller compared to conventional designs.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 5","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143496801","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":"Aligning nano-scale crystals in bulk materials","authors":"Xiangyi Zhang,&nbsp;Yingxin Hua,&nbsp;Xiaohong Li","doi":"10.1007/s11433-024-2572-5","DOIUrl":"10.1007/s11433-024-2572-5","url":null,"abstract":"<div><p>Crystal orientation determines various material performances including magnetic, electrical, and mechanical properties. However, achieving the alignment of nano-grains along a specific crystallographic orientation in bulk materials remains a formidable challenge. Departing from conventional approaches using polycrystalline materials, we report a strategy to overcome this challenge by deliberately introducing strain-energy anisotropy to select oriented nucleation/growth of crystals in amorphous materials. To demonstrate its efficacy, we employed ferromagnetic materials as a proof of concept. Using our approach, a range of previously inaccessible bulk ferromagnetic nanomaterials with strong <i>c</i>-axis orientation have been created. The resulting bulk oriented nano-grained magnets exhibit a high energy density, 168 kJ m⁻³ for SmCo₇ and 235.2 kJ m⁻³ for PrCo₅ ferromagnets, greatly surpassing that of their state-of-the-art counterparts with 23%–62% enhancement. Our strategy is general and applicable to other material systems, including thermoelectric, piezoelectric, and ferroelectric materials, to achieve the desired oriented nano-grains for technological applications.</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":"143466045","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}

{"title":"Polarization structure transition of C-point singularities upon reflection","authors":"Weiming Zhen,&nbsp;Zhi-Cheng Ren,&nbsp;Xi-Lin Wang,&nbsp;Jianping Ding,&nbsp;Hui-Tian Wang","doi":"10.1007/s11433-024-2589-6","DOIUrl":"10.1007/s11433-024-2589-6","url":null,"abstract":"<div><p>This paper provides a comprehensive study of the polarization transition of reflected C-point singularities. The reflection of star- and lemon-type C-point paraxial vector beams at an air-dielectric interface is investigated. For small oblique incidences, a topological phase transition is observed exclusively in spin-maintained modes, manifesting as a shift from a vortex phase to a spin phase. Notably, as the incident angle ranges from 0 to 90 degrees, another topological phase transition occurs, the total spin components of the reflected field undergoing an interchange of topological charges (TCs), resulting in a type transition of the C-point from the star (lemon)-type to the lemon (star)-type. Furthermore, the concurrence of the C-point beam throughout the reflection process can be modulated by the incident angle, spanning almost the entire spectrum from 0 to 1. The longitudinal and transverse displacements of each spin component as well as the overall beam shifts of the reflected beam are further analyzed, revealing their dependence on the incident beam’s TC combination. These findings offer novel physical insights into polarization singularity-matter interactions, holding promise for advancing research in singular optics and its applications.</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":"143466049","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":"Attenuation of Richtmyer-Meshkov instability growth of fluid layer via double shock","authors":"Chenren Chen,&nbsp;Jiaxuan Li,&nbsp;He Wang,&nbsp;Zhigang Zhai,&nbsp;Xisheng Luo","doi":"10.1007/s11433-024-2592-5","DOIUrl":"10.1007/s11433-024-2592-5","url":null,"abstract":"<div><p>Suppression of the hydrodynamic instabilities involved in the inertial confinement fusion has attracted much attention but remains a challenge. In this work, we report the first theoretical analysis and experimental validation on attenuating the instability growth of a shock-accelerated fluid layer through a second shock impact. An analytical model is established to predict linear growth rates of the perturbations at two interfaces of the layer by considering both the effects of interface coupling and reverberating waves. Theoretically, there are nine possibilities for simultaneously attenuating the instability growths of perturbations at the two interfaces. Accordingly, shock-tube experiments are specially designed and conducted, and nine possibilities are all realized by experiments, which verifies the reliability of the analytical model and also demonstrates the feasibility of attenuating the instability growth of a fluid layer via double shock.</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":"143466047","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":"New discoveries of young stars revise our star formation history in the Taurus Molecular Cloud","authors":"Gregory J. Herczeg","doi":"10.1007/s11433-025-2601-x","DOIUrl":"10.1007/s11433-025-2601-x","url":null,"abstract":"","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 4","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465978","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":"Space-based optical lattice clocks as gravitational wave detectors in search for new physics","authors":"Bo Wang,&nbsp;Bichu Li,&nbsp;Qianqian Xiao,&nbsp;Geyu Mo,&nbsp;Yi-Fu Cai","doi":"10.1007/s11433-024-2573-3","DOIUrl":"10.1007/s11433-024-2573-3","url":null,"abstract":"<div><p>We investigate the sensitivity and performance of space-based optical lattice clocks (OLCs) in detecting gravitational waves, in particular the stochastic gravitational wave background (SGWB) at low frequencies (10⁻⁴, 1) Hz, which are inaccessible to ground-based detectors. We first analyze the response characteristics of a single OLC detector for SGWB detection and compare its sensitivity with that of laser interferometer space antenna (LISA). Due to longer arm lengths, space-based OLC detectors can exhibit unique frequency responses and enhance the capability to detect SGWB in the low-frequency range, but the sensitivity of a single OLC detector remains insufficient overall compared with LISA. Then, as a preliminary plan, we adopt a method of cross-correlation on two OLC detectors to improve the signal-to-noise ratio (SNR). This method leverages the uncorrelated origins but statistically similar properties of noise in two detectors while the SGWB signal is correlated between them, thus achieving effective noise suppression and sensitivity enhancement. Future advancements in OLC stability are expected to further enhance their detection performance. This work highlights the potential of OLC detectors as a promising platform for SGWB detection, offering complementary capabilities to LISA, and opening an observational window into more astrophysical sources and the early universe.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"68 4","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465934","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}