Spin-Orbit Torque and Magnetization Switching in 2D Ferromagnetic Devices
二维铁磁器件中的自旋轨道转矩与磁化翻转
AI总结 通过第一性原理计算研究范德华异质双层Cr3Te4/PtTe2中的非平衡自旋转矩,发现局域自旋感应产生类场转矩主导面内磁各向异性体系的翻转电流,并强调优化NM层自旋霍尔效应和FM层Rashba效应分别对垂直和面内磁各向异性翻转的重要性。
二维铁磁器件中的自旋轨道转矩与磁化翻转
Bao-Huei Huang, Hong Guo, Yu-Hui Tang
AI总结 通过第一性原理计算研究范德华异质双层Cr3Te4/PtTe2中的非平衡自旋转矩,发现局域自旋感应产生类场转矩主导面内磁各向异性体系的翻转电流,并强调优化NM层自旋霍尔效应和FM层Rashba效应分别对垂直和面内磁各向异性翻转的重要性。
电流诱导的自旋轨道转矩已成为操控基于铁磁体/非磁体(FM/NM)存储单元磁化翻转的有力技术。通过研究范德华异质双层三角晶格Cr3Te4/PtTe2中的非平衡自旋转矩效应,采用第一性原理量子输运计算来确定局域自旋感应(由FM层中的Rashba-Edelstein效应产生)和自旋电流注入(从NM层流向FM层)。我们的工作揭示,局域自旋感应显著产生类场转矩,该转矩主要主导具有强面内磁各向异性体系中的翻转电流。我们的工作强调了优化NM层中的自旋霍尔效应用于基于垂直磁各向异性(PMA)的磁化翻转,以及最大化FM层中的Rashba效应用于基于面内磁各向异性(IMA)的翻转的重要性。
Current-induced spin-orbit torque has emerged as a powerful technique for manipulating magnetization switching of ferromagnet/nonmagnet (FM/NM) based memory cell. By investigating nonequilibrium spin torque effect in a van der Waals heterobilayer, trigonal $\text{Cr}_{3}\text{Te}_{4}/\text{PtTe}_{2}$, the first-principles quantum transport calculations are applied to determine both local spin induction, resulting from Rashba-Edelstein effect in the FM layer, and spin current injection, flowing from the NM to the FM layer. Our work reveals that local spin induction significantly generates the fieldlike torque, which primarily governs the switching current in systems with strong in-plane magnetic anisotropy. Our work emphasizes the importance of optimizing spin Hall effect in the NM layer for perpendicular magnetic anisotropy (PMA)-based magnetization switching and maximizing the Rashba effect in the FM layer for in-plane magnetic anisotropy (IMA)-based switching.
铀的复合及其在千新星光谱中的应用探索
Niamh Ferguson, Anders Jerkstrand, Smaranika Banerjee, Martin. G. O'Mullane, Nigel.R.Badnell
AI总结 针对千新星非局部热力学平衡阶段主导的双电子复合过程,利用AUTOSTRUCTURE优化开放f壳层铀离子U II-U IV的复合速率系数,并通过Nd III基准验证,以改进辐射传输计算中光谱对复合物理的敏感性。
双电子复合(DR)预计是千新星非局部热力学平衡(non-LTE)阶段的主要复合过程,然而大多数重离子仍缺乏可靠的DR数据。因此,当前的光谱模型依赖于简化的复合方案,给预测光谱带来了显著的不确定性。我们提出了一种针对开放f壳层离子的优化策略,使用\ exttt{AUTOSTRUCTURE},目标是千新星抛射物中相关的铀离子U II--U IV。作为基准案例,对Nd III进行了计算,以验证f壳层结构及其对DR影响的处理。得到的DR速率系数在千新星等离子体相关温度下约为$10^{-10}$--$10^{-12}$ cm$^{3}$s$^{-1}$。优化后的速率旨在用于\ exttt{SUMO}的辐射传输计算,以评估千新星光谱对改进复合物理的敏感性。Nd III基准表明,原子结构的改进可以引起光谱特征的可测量变化,这为锕系离子的类似计算提供了动力。
Dielectronic recombination (DR) is expected to be the dominant recombination process during the non-local thermodynamic equilibrium (non-LTE) phase of kilonovae, yet reliable DR data remain unavailable for most heavy ions. Current spectral models therefore rely on simplified recombination prescriptions, introducing significant uncertainties into predicted spectra. We present an optimization strategy for open f-shell ions using \texttt{AUTOSTRUCTURE}, targeting uranium ions U II--U IV relevant to kilonova ejecta. As a benchmark case, calculations are performed for Nd III to validate the treatment of the f-shell structure and its impact on DR. The resulting DR rate coefficients are of order $10^{-10}$--$10^{-12}$ cm$^{3}$s$^{-1}$ over temperatures relevant to kilonova plasmas. The optimized rates are intended for implementation in radiative-transfer calculations with \texttt{SUMO} to assess the sensitivity of kilonova spectra to improved recombination physics. The Nd III benchmark demonstrates that refinements to the atomic structure can produce measurable changes in spectral features, motivating similar calculations for actinide ions.
多波长原子干涉仪的无模糊惯性测量
Wei-Chen Jia, Yue Xin, Ke Shen, Yan-Ying Feng
AI总结 通过多波长原子干涉合成包络实现无模糊惯性测量,实验演示了双轴旋转与加速度传感,并解决了传统原子干涉仪的相位模糊问题。
白光干涉通过合成多个光学波长的干涉包络实现无模糊定位,但相干物质波尚未实现类似能力。本文首次实验演示了多波长原子干涉,建立了白光干涉的物质波对应。通过利用反向传播原子束作为多波长物质波源并合成其光谱分量的干涉包络,我们实现了基于包络定位而非传统条纹相位估计的惯性测量。由此产生的多尺度干涉响应提供了无模糊操作、明确的旋转比例因子以及对初始相位偏差的降低敏感性。作为原理验证,我们演示了同时双轴旋转和加速度传感,并直接解决了从根本上限制传统开环原子干涉仪的相位模糊。我们进一步测量了地球自转,相对误差为4.3%,在15000秒平均时间下长期稳定性为93 ppm。我们的结果将多波长原子干涉确立为相干物质波传感的新范式,将白光干涉原理扩展到原子光学,并为惯性传感、大地测量、精密计量和惯性导航开辟了新机遇。
White-light interferometry enables ambiguity-free localization by synthesizing interference envelopes from multiple optical wavelengths, but no analogous capability has been realized for coherent matter waves. Here we report the first experimental demonstration of multi-wavelength atom interferometry, establishing the matter-wave counterpart of white-light interferometry. By exploiting counter-propagating atomic beams as multi-wavelength matter wave sources and synthesizing interference envelopes from their spectral components, we realize inertial measurements based on envelope localization rather than conventional fringe-phase estimation. The resulting multi-scale interferometric response provides ambiguity-free operation, a well-defined rotational scale factor, and reduced sensitivity to initial phase bias. As a proof of principle, we demonstrate simultaneous dual-axis rotation and acceleration sensing and directly resolve the phase ambiguity that fundamentally limits conventional open-loop atom interferometers. We further measure the Earth's rotation with a relative error of 4.3% and a long-term stability of 93 ppm at an averaging time of 15,000 s. Our results establish multi-wavelength atom interferometry as a new paradigm for coherent matter-wave sensing, extending the principles of white-light interferometry to atom optics and opening new opportunities for inertial sensing, geodesy, precision metrology, and inertial navigation.
机器学习中的时间序列分析
Antonio Pagliaro, Anna Anzalone
AI总结 从机器学习视角综述时间序列分析,涵盖经典统计模型与现代机器学习方法,强调跨领域应用原则。
时间序列分析是机器学习的基本组成部分,尤其是在天体物理学和宇宙学中,时域数据丰富。本章从机器学习的视角对时间序列分析技术进行了教学性综述。我们涵盖了时间序列的基本概念(平稳性、自相关、季节性)、经典统计模型(自回归、移动平均、ARIMA、指数平滑、状态空间模型)以及现代机器学习方法。特别地,我们讨论了传统统计方法如何奠定基础,然后探索了用于时间序列的机器学习方法,包括基于特征的回归、基于树的集成方法、隐马尔可夫模型、高斯过程和深度学习模型(循环神经网络、卷积网络、变换器)。在整章中,我们通过来自多个领域(例如天文学、天气预报、金融)的示例进行说明,以强调共同原则。目标是使读者具备理论理解和实践背景,以便在其研究中应用机器学习技术进行时间序列分析。
Time series analysis is a fundamental component of machine learning, especially in astrophysics and cosmology where temporal data abound. This chapter provides a pedagogical review of time series analysis techniques from a machine learning perspective. We cover the basic concepts of time series (stationarity, autocorrelation, seasonality), classical statistical models (autoregressive, moving average, ARIMA, exponential smoothing, state-space models), and modern machine learning approaches. In particular, we discuss how traditional statistical methods lay the groundwork, and then explore machine learning methods for time series, including feature-based regression, tree-based ensemble methods, hidden Markov models, Gaussian processes, and deep learning models (recurrent neural networks, convolutional networks, transformers). Throughout, we illustrate with examples drawn from multiple domains (e.g. astronomy, weather forecasting, finance) to emphasize common principles. The goal is to equip readers with both the theoretical understanding and practical context to apply machine learning techniques for time series analysis in their research.
电子-正电子湮灭中微扰和指数化初态辐射修正的匹配
Andrej Arbuzov, Uliana Voznaya
AI总结 分析电子-正电子湮灭过程中初态辐射的高阶修正行为,提出同时指数化纯光子和非单态对修正的新方案,并与现有高阶解析计算匹配。
分析了电子-正电子湮灭过程中初态辐射引起的高阶辐射修正行为。给出了未来对撞机能量下的数值结果。估计了这些修正已知结果的不确定性。提出了一种同时指数化纯光子和非单态对修正的改进方案。构建了指数化结果与现有解析高阶计算的匹配。讨论了一种新的类似DIS的减除方案。
The behavior of higher-order radiative corrections due to initial state radiation in processes of electron-positron annihilation is analyzed. Numerical results for energies of future colliders are presented. Uncertainties of the known results on these corrections are estimated. A modified scheme for simultaneous exponentiation of pure photonic and non-singlet pair corrections is presented. Matching of the exponentiated results with the existing analytic higher-order calculations is constructed. A new DIS-like subtraction scheme is discussed.
成像大气切伦科夫望远镜中事件重建的机器学习
Antonio Pagliaro, Antonino La Barbera
AI总结 综述机器学习在成像大气切伦科夫望远镜事件重建中的应用,包括粒子分类和能量/方向回归,并介绍基于时序特征和集成方法的新进展。
成像大气切伦科夫望远镜(IACT)是甚高能(VHE)伽马射线天文学的主要仪器,覆盖从数百GeV到数百TeV的能量范围。本章回顾了机器学习在重建IACT探测粒子物理性质中的关键作用。我们介绍了IACT技术及其核心挑战:从大量的宇宙射线背景中区分稀有的伽马射线簇射。我们详细介绍了标准重建流程,从图像清洗和Hillas参数化到立体观测,并将事件重建框架化为一个监督学习问题,包括粒子分类和能量/方向回归。然后探讨了两个创新前沿:利用簇射图像的时间维度,通过基于时序的新特征增强低能量下的背景抑制;以及应用先进的集成方法(梯度提升、堆叠),这些方法超越了基线随机森林,特别是在减轻系统性能量偏差方面。最后,我们讨论了性能指标,并对以深度学习为主的下一代方法进行了展望,包括卷积神经网络和图神经网络。
Imaging Atmospheric Cherenkov Telescopes (IACTs) are the leading instruments for very-high-energy (VHE) gamma-ray astronomy, covering the range from hundreds of GeV to hundreds of TeV. This chapter reviews the critical role of machine learning in reconstructing the physical properties of particles detected by IACTs. We introduce the IACT technique and its central challenge: distinguishing rare gamma-ray showers from the overwhelming cosmic-ray background. We detail the standard reconstruction pipeline, from image cleaning and Hillas parameterization to stereoscopic observation, and frame event reconstruction as a supervised learning problem encompassing particle classification and energy/direction regression. Two frontiers of innovation are then explored: the exploitation of the temporal dimension of shower images through novel timing-based features that enhance background rejection at low energies, and the application of advanced ensemble methods (gradient boosting, stacking) that surpass baseline Random Forests, notably in mitigating systematic energy bias. Finally, we discuss performance metrics and provide an outlook on next-generation approaches dominated by deep learning, including Convolutional and Graph Neural Networks.
近地系外行星的机器学习聚类:与卵石吸积的联系
Yi Duann, Anders Johansen, Haiyang S. Wang, H. Jens Hoeijmakers
AI总结 利用高斯混合模型对近地系外行星进行无监督聚类,揭示其内在子群,并通过卵石吸积合成种群解释形成路径差异。
近地系外行星展现出由形成条件和迁移过程塑造的广泛轨道构型和物理性质。尽管种群合成模型预测了不同的行星种群,但在观测到的系外行星与合成种群之间建立定量联系仍然具有挑战性。我们使用物理驱动的动力学参数研究近地系外行星的内在组织,并将所得种群与卵石吸积形成路径联系起来。将两阶段高斯混合模型应用于观测到的近地系外行星样本,在由行星-恒星相互作用的动力学描述符主导的特征空间中进行无监督概率聚类。将所得聚类映射到统计驱动的三维参数空间中的卵石吸积合成种群。然后使用与形成相关的量(包括气体可用性、气体分数和冰岩质量比)来解释映射的种群。我们在不施加预定义分类边界的情况下识别出统计上支持的子群,包括超大质量气态巨行星、热巨行星、暖木星主导系统和低质量巨行星。映射的合成种群揭示了形成时间、气体吸积和固体增长历史的系统性差异。特别是,超大质量气态巨行星比热巨行星和暖木星主导种群更倾向于与更早的形成时期相关联。这些结果表明,物理驱动的机器学习方法可以为观测到的系外行星种群与理论行星形成路径之间的联系提供统计上稳健的框架。
Close-in exoplanets exhibit a wide range of orbital architectures and physical properties shaped by both formation conditions and migration processes. Although population-synthesis models predict distinct planetary populations, establishing a quantitative connection between observed exoplanets and synthetic populations remains challenging. We investigate the intrinsic organisation of close-in exoplanets using physically motivated dynamical parameters and connect the resulting populations to pebble-accretion formation pathways. A two-stage Gaussian mixture model (GMM) is applied to an observed sample of close-in exoplanets, performing unsupervised probabilistic clustering in a feature space dominated by dynamical descriptors of planet-star interactions. The resulting clusters are mapped onto a pebble-accretion synthetic population within a statistically motivated three-dimensional parameter space. Formation-related quantities, including gas availability, gas fraction, and ice-rock mass ratio, are then used to interpret the mapped populations. We identify statistically supported sub-populations without imposing predefined classification boundaries, including very-massive gas giants, hot giants, warm-Jupiter-dominated systems, and lower-mass giants. The mapped synthetic populations reveal systematic differences in formation timing, gas accretion, and solid growth histories. In particular, very-massive gas giants are preferentially associated with earlier formation epochs than hot-giant and warm-Jupiter-dominated populations. These results demonstrate that physically motivated machine-learning approaches can provide a statistically robust framework for linking observed exoplanet populations to theoretical planet formation pathways.
第二银象限分子云亚结构的几何与运动学
Wen Ge, Fujun Du
AI总结 基于MWISP巡天数据,分析分子云亚结构的投影形态和相对取向,发现其沿银经方向略伸长,速度梯度垂直于主轴,磁场平行于主轴,且尺度依赖。
我们分析了来自MWISP巡天无偏星表中分子云内亚结构的几何和运动学。这些亚结构被定义为每个云峰值积分强度20%等值线所包围的空间连通区域。在应用体素大小选择标准并排除被地图边界截断的结构后,我们构建了一个样本,并使用投影尺度比$R=\Delta b/(\Delta l\cdot\cos b)$量化其投影形态。该比率本质上测量$\tan\theta$,其中$\theta$是细长纤维相对于银道面的天球角。所得样本的中值$R=0.96$,表明沿银经方向存在轻微但系统的伸长倾向。这种趋势在更大空间尺度上变得更加明显。我们进一步研究了结构主轴、速度梯度方向以及从Planck数据导出的天球磁场方向之间的相对取向,针对一个定义良好的结构子样本。我们发现,在我们的样本中的云结构(物理尺度约0.3至约30 pc)中,速度梯度倾向于垂直于主轴,而磁场通常平行于主轴。这个尺度范围不同于通常研究稠密核(约0.05 pc)和GMC尺度结构($\gtrsim$ 10至100 pc)所探测的尺度,这些研究报道了相对取向的尺度依赖变化。此外,速度梯度与磁场之间的对齐随物理尺度增加而逐渐减弱。这些结果表明,分子云亚结构观测到的各向异性可能源于大尺度银河动力学、各向异性气体运动和磁场的共同作用,且这些效应的相对重要性随尺度变化。
We analyze the geometry and kinematics of substructures within molecular clouds identified in an unbiased catalog from the MWISP survey. These substructures are defined as spatially connected regions enclosed by the 20% peak-integrated-intensity contour of each cloud. After applying selection criteria on voxel size and excluding structures truncated by map boundaries, we construct a sample and quantify their projected morphology using the projected scale ratio $R=\Delta b/(\Delta l\cdot\cos b)$. This ratio essentially measures $\tan\theta$ where $\theta$ is the plane-of-sky angle of an elongated filament relative to the Galactic plane. The resulting sample exhibits a median $R=0.96$, indicating a slight but systematic preference for elongation along Galactic longitude. This tendency becomes more pronounced at larger spatial scales. We further investigate the relative orientations among the structural major axes, velocity-gradient directions, and plane-of-sky magnetic-field orientations derived from Planck data for a subsample of well-defined structures. We find that, for cloud structures within our sample, with physical scale $\sim 0.3$ to $\sim 30$ pc, velocity gradients tend to be perpendicular to the major axes, while magnetic-field are generally aligned parallel to them. This scale range differs from those typically probed in studies of dense cores ($\sim 0.05$ pc) and GMC-scale structures ($\gtrsim$ 10 to 100 pc), which have reported scale-dependent variations in relative orientations. In addition, the alignment between velocity gradients and magnetic fields shows a gradual weakening with increasing physical scale. These results suggest that the observed anisotropy of molecular cloud substructures may arise from a combination of large-scale Galactic dynamics, anisotropic gas motions, and magnetic fields, with the relative importance of these effects varying with scale.
旋转 $\mathcal{N}=2,U(1)^2$ 规范超引力黑洞中的 Comisso-Asenjo 机制:与 Kerr 黑洞的扩展比较
Abhinav Jaguri, Hemwati Nandan, Pankaj Sheoran, Sanjar Shaymatov
AI总结 研究旋转超引力黑洞中 Comisso-Asenjo 磁重联能量提取过程,分析参数对提取能量、效率和功率的影响,发现低自旋下效率可超 Kerr 极端情况,并用 Kendall's Tau 识别关键参数。
在本文中,我们研究了在耦合的 $\mathcal{N}=2,\\,U(1)^2$ 规范超引力黑洞(BH)附近通过 Comisso-Asenjo (CA) 磁重联过程进行的能量提取。我们的研究聚焦于独立参数集 $p_i\in(N_g,g,v,e)$ 与自旋参数 $a$ 对提取能量 ($\epsilon_{\pm}$)、效率 ($\eta$) 和提取功率 ($\mathcal{P}_{CA}$) 的联合影响,旨在识别在某些情况下以低于 Kerr 极端情况 ($a\sim1$) 的自旋 ($a\sim0.39$) 实现更高效率能量提取的最优组合。利用时空参数,我们探索了导致不同时空的各种情况,并与 Kerr 黑洞 (KBH) 进行了扩展比较。我们还研究了取向角 ($\xi$) 和磁化参数 ($\sigma_0$) 对效率和提取功率的影响。通过研究低参数组合 $[\\,\forall p_i<0.2 \land N_g<0.08\\,]$、中参数组合 $[\\,\exists p_i\ge0.5 \land N_g\in(0.08,0.15)\\,]$、高参数组合 $[\\,\exists p_i>0.7 \land N_g\in(0.16,0.23)\\,]$ 和混合参数组合 $[\\,\forall p_i\in(0,1) \land N_g\in(0,0.23)\\,]$,我们仅探索了所有时空参数的极端情况,并证明了可以超过极端 Kerr 效率极限 ($\eta>1.495$)。统计 Kendall's Tau 方法使我们能够识别在能量提取过程中起增强或抑制作用的关键独立参数,并可视化 $(N_g,g,v,e)$ 与物理输出 $(a_{\rm ext},r_E,r_{\rm ergo},\epsilon_{\pm},\eta,\mathcal{P}_{CA},R_{\eta},R_{\mathcal{P}})$ 之间的关系。此外,我们表明旋转黑洞时空中的可观测 Lundquist 数 $S_{\rm obs}$ 通过 lapse 函数 ($\alpha$) 获得了依赖于观测者的角度依赖性。这导致在用可观测物理量表达时偏离标准的 Sweet-Parker 标度律。
In this paper, we investigate energy extraction via the Comisso-Asenjo (CA) magnetic reconnection process near a coupled $\mathcal{N}=2,\,U(1)^2$ gauged supergravity Black Hole (BH). Our study focuses on the combined impact of the independent parameter set $p_i\in(N_g,g,v,e)$ with the spin parameter $a$ on the extracted energy ($\epsilon_{\pm}$), efficiency ($\eta$), and extracted power ($\mathcal{P}_{CA}$), aiming to identify optimal combinations where energy can be extracted with higher efficiency in certain cases at lower spin $(a\sim0.39)$ than the Kerr extremal case $(a\sim1)$. Using the spacetime parameters, we explore various cases leading to distinct spacetimes and provide an extended comparison with the Kerr Black Hole (KBH). We also examine the influence of the orientation angle ($\xi$) and magnetization parameter ($\sigma_0$) on both efficiency and extracted power. Investigating low $[\,\forall p_i<0.2 \land N_g<0.08\,]$, mid $[\,\exists p_i\ge0.5 \land N_g\in(0.08,0.15)\,]$, high $[\,\exists p_i>0.7 \land N_g\in(0.16,0.23)\,]$, and mixed $[\,\forall p_i\in(0,1) \land N_g\in(0,0.23)\,]$ parameter combinations, we explore only extremal cases for all spacetime parameters and demonstrate that the extremal Kerr efficiency limit ($\eta>1.495$) can be exceeded. The statistical Kendall's Tau approach allows us to identify the key independent parameters acting as boosters or dampers in the energy extraction process and to visualize the relationship between $(N_g,g,v,e)$ and the physical outputs $(a_{\rm ext},r_E,r_{\rm ergo},\epsilon_{\pm},\eta,\mathcal{P}_{CA},R_{\eta},R_{\mathcal{P}})$. Furthermore, we show that the observable Lundquist number $S_{\rm obs}$ in rotating BH spacetimes acquires an observer-dependent angular dependence through the lapse function $(\alpha)$. This leads to deviations from the standard Sweet-Parker scaling when expressed in terms of observable quantities.
退相氢超精细系统中的量子关联层次与隐形传态
Geerthana Thiyagarajan, R. Muthuganesan
AI总结 研究氢超精细自旋系统在马尔可夫相位噪声下的量子关联动力学,发现纠缠最脆弱,平均转向相干性最鲁棒,且退相热态可用于量子隐形传态,其优势窗口与纠缠生存区间精确重合。
我们研究了受马尔可夫相位噪声影响的氢超精细自旋系统中量子关联的动力学。将电子和质子自旋自由度视为由各向同性超精细哈密顿量和局域退相控制的开两量子比特系统,我们得到了精确的含时密度矩阵,并推导了完整X态族的解析表达式。我们以闭合形式计算了并发度($C$)、迹距离测量诱导非定域性(Trace MIN--$\mathcal{N}_1$)和平均转向相干性(ASC),并建立了它们在所有时刻的严格排序$ C(t)\leq \mathcal{N}_1(t)\leq \mathrm{ASC}(t) $。纠缠被确定为最脆弱的资源,在有限时间内经历突然死亡。对于具有非零布居数不平衡的态,Trace MIN表现出对退相免疫的冻结现象,而ASC是最鲁棒的量,在每种情况下持续最长时间。我们还证明了退相热超精细态可作为量子隐形传态的资源,推导了平均保真度的闭合表达式,并建立了对于具有最大混合边缘的完整X态族,隐形传态优势窗口与纠缠生存区间精确重合,即$\mathcal{F}_A > 2/3 \Longleftrightarrow \mathcal{C} > 0$。我们识别了四个不同的动力学区域,并将所有三种关联度量映射到可直接测量的泡利自旋关联子上,从而无需完整态层析即可实验重建完整的关联层次。
We study the dynamics of quantum correlations in the hydrogen hyperfine spin system subject to Markovian phase noise. Treating the electron and proton spin degrees of freedom as an open two-qubit system governed by an isotropic hyperfine Hamiltonian and local dephasing, we obtain the exact time-dependent density matrix and derive analytical expressions for the full X-state family. We compute concurrence($C$), trace-distance measurement-induced nonlocality (Trace MIN--$\mathcal{N}_1$), and average steering coherence (ASC) in closed form and establish their strict ordering $ C(t)\leq \mathcal{N}_1(t)\leq \mathrm{ASC}(t) $ at all times. Entanglement is identified as the most fragile resource, undergoing sudden death at a finite time. Trace MIN exhibits dephasing-immune freezing for states with nonzero population imbalance, while ASC is the most robust quantity, persisting longest in every scenario this http URL additionally demonstrate that the dephased thermal hyperfine state serves as a resource for quantum teleportation, deriving a closed-form expression for the average fidelity and establishing that the teleportation advantage window coincides exactly with the entanglement survival interval, $\mathcal{F}_A > 2/3 \Longleftrightarrow \mathcal{C} > 0$, for the full X-state family with maximally mixed marginals. We identify four distinct dynamical regimes and map all three correlation measures onto directly measurable Pauli spin correlators, enabling experimental reconstruction of the full hierarchy without full state tomography.
定制软腔以实现稳健的分子强耦合
Siddharaj M. Gadge, Adarsh B. Vasista
AI总结 通过实验和理论分析,发现当腔线宽与分子线宽匹配时,软腔中分子强耦合的鲁棒性最优,为设计形态依赖的腔提供了新框架。
如何设计高效的化学开放光学腔以实现分子强耦合?解决这个问题对于开发动态可调光-物质相互作用的软腔平台至关重要,其中直接访问受限电磁模式是必不可少的。传统的腔品质因数如$Q/\sqrt{V}$和协同性成功描述了光谱限制和耗散,但未能完全捕捉腔与分子自由度之间线宽不对称性的作用。在这里,我们通过在大范围内改变聚苯乙烯微球半径,系统地研究了TDBC染料分子与微球回音壁模式之间的强耦合。为了量化强耦合的鲁棒性,我们定义了参数$\chi = \frac{g}{\max(\kappa,\gamma)}$,其中$g$是耦合强度,$\kappa$和$\gamma$分别表示腔和分子线宽。尽管由于模式体积缩放,耦合强度随腔尺寸增加而单调下降,但我们发现$\chi$在$\kappa \approx \gamma$条件附近表现出明显的最大值。这一观察表明,线宽匹配不仅是改善光谱可见性的标准,而且反映了一种耗散匹配条件,该条件优化了软腔中相干光-物质交换的鲁棒性。我们的结果为设计用于分子强耦合的形态依赖腔提供了替代框架。
How should one design efficient chemically open optical cavities for molecular strong coupling? Addressing this question is important for the development of soft-cavity platforms for dynamically tunable light--matter interactions, where direct access to confined electromagnetic modes is essential. Conventional cavity figures of merit such as $Q/\sqrt{V}$ and cooperativity successfully describe spectral confinement and dissipation but do not fully capture the role of linewidth asymmetry between cavity and molecular degrees of freedom. Here, we systematically investigate strong coupling between TDBC dye molecules and whispering gallery modes of polystyrene microspheres by varying the microsphere radius over a broad range. To quantify the robustness of strong coupling, we define the parameter $\chi = \frac{g}{\max(\kappa,\gamma)}$, where $g$ is the coupling strength, while $\kappa$ and $\gamma$ denote the cavity and molecular linewidths, respectively. Although the coupling strength decreases monotonically with increasing cavity size due to mode-volume scaling, we find that $\chi$ exhibits a pronounced maximum near the condition $\kappa \approx \gamma$. This observation suggests that linewidth matching is not merely a criterion for improved spectral visibility, but reflects a dissipation-matching condition that optimizes the robustness of coherent light--matter exchange in soft-cavities. Our results provide an alternative framework for designing morphology-dependent cavities for molecular strong coupling.
通过引力波探测圈量子引力带电黑洞的周期轨道
Abolhassan Mohammadi, Arun Kumar, Hongwei Tan, Sushant G. Ghosh
AI总结 研究圈量子引力带电黑洞时空中极端质量比旋近的周期轨道,通过Levin-Perez-Giz分类和引力波波形分析,发现LQG参数影响波形振幅和相位,特征应变在毫赫兹波段超过LISA等探测器灵敏度。
来自极端质量比旋近(EMRI)的引力波提供了黑洞强场几何的直接探针。受此启发,我们研究了圈量子引力(LQG)启发的带电黑洞时空中测试粒子的运动及其产生的引力波辐射,其中经典奇点被由LQG聚合产生的平滑过渡面取代,其半径由LQG面积间隙条件设定。因此,聚合参数$\delta_b$由质量$M$和电荷参数$Q$唯一确定,使得本文研究的所有情况都包含LQG修正。通过构建有效势,确定了最内稳定圆轨道(ISCO)和边际束缚轨道(MBO)。使用Levin-Perez-Giz zoom-whirl分类对周期轨道进行分类,展示了轨道拓扑如何塑造波形,每个闭合轨迹由三元整数$(z, w, v)$标记,并通过有理频率比$q = \omega_\phi/\omega_r - 1$定位。在四极近似下,估计了EMRI的引力波形,并在时域和频域中得到了极化。时域中的极化表现出zoom-whirl形态,波形振幅和相位依赖于LQG参数。对于所有电荷参数$Q$的值,特征应变峰值位于毫赫兹波段,并超过了LISA、Taiji和天琴计划的预期灵敏度,表明未来观测可能对强场区域中的LQG聚合参数施加有意义的约束。
Gravitational waves from extreme-mass-ratio inspirals (EMRI) provide a direct probe of the strong-field geometry of black holes. Motivated by this, we study the motion of test particles and the resulting gravitational wave emission in the spacetime of a charged black hole inspired by loop quantum gravity (LQG), where the classical singularity is replaced by a smooth transition surface arising from the LQG polymerization, in which its radius is set by the LQG area gap condition. As a result, the polymerization parameter $\delta_b$ is uniquely determined by the mass $M$ and charge parameter $Q$, so that all cases examined in this work contain LQG correction. By constructing the effective potential, the innermost stable circular orbit (ISCO) and the marginally bound orbit (MBO) are determined. Periodic orbits are classified using the Levin-Perez-Giz zoom-whirl taxonomy, showing how the orbit topology shapes the waveform, so that each closed trajectory is labeled by the triple integer $(z, w, v)$ and located through the rational frequency ratio $q = \omega_\phi/\omega_r - 1$. Within the quadrupole approximation, the gravitational waveforms for an EMRIs are estimated, and the resulting polarizations are obtained in the time-domain and frequency-domain. The resulting polarizations in the time-domain exhibit a zoom-whirl morphology, with the waveform amplitude and phase dependent on the LQG parameter. The characteristic strain peaks in the millihertz band for all values of the charge parameter $Q$, and they exceed the projected sensitivities of LISA, Taiji, and TianQin, suggesting that future observations could place meaningful constraints on the LQG polymerization parameter in the strong-field regime.
具有常数状态方程再加热和动态再加热分析的反切膨胀的贝叶斯约束
Mayur Abhisheki, Prasanta Kumar Das
AI总结 基于反切势的暴胀模型,结合常数和动态状态方程再加热,通过贝叶斯推断约束参数,发现再加热动力学在连接早期暴胀与晚期宇宙学参数推断中起关键作用。
我们对基于反切势的暴胀模型进行了贝叶斯推断分析,在常数和动态状态方程(DEOS)框架中纳入了再加热动力学。利用普朗克和ACT对标量谱指数的约束,我们发现偏好值$\kappa\simeq0.5-0.6$和$N_k\simeq40-60$,导致再加热温度$T_{RH}\sim10^{10}-10^{14}$ GeV和再加热持续时间$N_{RH}\sim3-36$ e-fold。再加热加权的$H_0$后验通过CMB似然的固有$n_s-H_0$简并性将普朗克推断推向ACT偏好区域。在DEOS框架中,具有恒定衰减速率的再加热产生$N_{RH}\simeq4-8$ e-fold和$T_{RH}\simeq10^{13}$ GeV,而动态衰变速率则产生对汤川耦合$y$的强依赖性,$N_{RH}$从$\mathcal{O}(30)$到$\mathcal{O}(1)$ e-fold变化,再加热温度跨度约为$10^{-2}-10^{14}$ GeV。施加暴胀-再加热一致性显著地将可行参数空间限制在$n_s\simeq0.9720-0.9725$和$r\simeq0.026-0.060$的狭窄区域,表明再加热动力学为早期宇宙暴胀与晚期宇宙学参数推断之间提供了非平凡的桥梁。
We perform a Bayesian inference analysis of an inflationary model based on an inverse-tangent potential, incorporating reheating dynamics in both constant and dynamical equation-of-state (DEOS) frameworks. Using Planck and ACT constraints on the scalar spectral index, we find preferred values $\kappa\simeq0.5-0.6$ and $N_k\simeq40-60$, leading to reheating temperatures $T_{RH}\sim10^{10}-10^{14}$ GeV and reheating durations $N_{RH}\sim3-36$ e-folds. Reheating weighted $H_0$ posteriors shift the Planck inference towards the ACT preferred region through the intrinsic $n_s-H_0$ degeneracy of the CMB likelihood. In the DEOS framework, reheating with a constant decay rate yields $N_{RH}\simeq4-8$ e-folds and $T_{RH}\simeq10^{13}$ GeV, while a dynamical decay rate produces a strong dependence on the Yukawa coupling $y$, with $N_{RH}$ varying from $\mathcal{O}(30)$ to $\mathcal{O}(1)$ e-folds and the reheating temperature spanning $\sim10^{-2}-10^{14}$ GeV. Imposing inflation-reheating consistency significantly restricts the viable parameter space to a narrow region around $n_s\simeq0.9720-0.9725$ and $r\simeq0.026-0.060$, demonstrating that reheating dynamics provide a nontrivial bridge between early-universe inflation and late-time cosmological parameter inference.
环境与压力依赖的超导性及储氢潜力:四元氢化物LiMgZr2H12的第一性原理综合研究
Jubair Hossan Abir, Tauhidur Rahman, Salauddin Muhammad Anis, Saleh Hasan Naqib, Raihana Shams Islam
AI总结 通过第一性原理计算,设计并研究了LiMgZr2H12的结构稳定性、电子性质、超导转变温度及储氢能力,发现其在常压下Tc达72.76 K,并具有5.36 wt%的储氢容量。
分子氢化物因其氢准分子单元在超导中电子不活跃,在寻找高Tc超导体方面受到的关注相对较少。相比之下,高压下的富氢化合物被广泛认为是实现室温超导的有力候选,但它们对极端压力条件的依赖严重限制了实际应用。本研究探索了可能在常压条件下稳定的富氢超导材料。受近期对MgZrH2n家族研究的启发,设计了一种具有Pmmm对称性的LiMgZr2H12结构。利用第一性原理计算,系统研究了该化合物的力学、热力学和动力学稳定性,以及其电子和光学性质。与MgZrH6相比,Li掺杂LiMgZr2H12显著增加了费米能级(EF)附近的氢衍生贡献,并增强了电子-声子耦合常数(λ)。LiMgZr2H12在常压下表现出72.76 K的临界温度,施加压力可进一步提高:在10 GPa时临界温度升至77.3 K。弹性质分析表明,该材料在研究的压力范围(0-10 GPa)内保持机械稳定,且表现为适合载流应用的延性材料。该材料具有高可加工性指数,远高于不锈钢。此外,LiMgZr2H12的重力储氢容量为5.36 wt%,表明其作为混合储氢技术有前景的候选材料。这项工作为设计常压条件下的高Tc氢化物提供了新方向。
Molecular hydrides have attracted relatively less attention in the search for high Tc superconductors because their hydrogen quasi-molecular units tend to be electronically inactive for superconductivity. In contrast, hydrogen rich compounds under high pressure have been widely considered strong candidates for achieving room-temperature superconductivity. However, their dependence on extreme pressure conditions significantly constrains their practical applicability. This work investigates hydrogen-rich superconducting materials that may be stable under ambient pressure conditions. Motivated by recent studies on the MgZrH2n family, a LiMgZr2H12 structure with Pmmm symmetry was designed. The mechanical, thermodynamic, and dynamical stability of the compound, together with its electronic and optical properties, were systematically investigated using first-principles calculations. Li doping in LiMgZr2H12 significantly increases the hydrogen derived contribution near the Fermi level (EF) and strengthens the electron-phonon coupling constant ({\lambda}) compared with MgZrH6. LiMgZr2H12 exhibits a critical temperature of 72.76 K at ambient pressure, which is further enhanced by applying pressure. At 10 GPa the critical temperature increases to 77.3 K. Elastic property analysis shows that the material remains mechanically stable over the pressure range studied (0-10 GPa). It also behaves like a ductile material suitable for current carrying applications. The material has a high machinability index, which is much higher than that of stainless steels. In addition, LiMgZr2H12 exhibits a gravimetric hydrogen storage capacity of 5.36 wt%, indicating its potential as a promising candidate for hybrid hydrogen storage technologies. This work offers a new direction for designing high-Tc hydrides at ambient conditions.
新$D_s$族分子态的证据
Dan Jiang, Yin Huang, JiongJiong Zhao
AI总结 通过高斯展开法求解薛定谔方程,发现$D_{s1}(2700)$、$D_{s1}(2860)$和$D_{s3}(2860)$可解释为$K^*D^{(*)}$分子态,并预言了其他分子态。
受观测到的$KD^{(*)}$分子候选态$D_{s0}(2317)$和$D_{s1}(2460)$的启发,其底-奇异对应态$K\bar{B}^{(*)}$分子态自然也被预期存在,尽管尚未在实验上确立。这一差异可能反映了显著的重夸克味对称性破缺,从而引入了较大的模型不确定性。当前对重夸克味对称性破缺效应的研究仍表现出强烈的参数依赖性,需要进一步的实验输入来约束这些效应,特别是关于可能的额外$K^{(*)}D^{(*)}$和$K^{(*)}\bar{B}^{(*)}$分子态。在这项工作中,我们检验了在观测到的$D_s$共振态中能否识别出额外的$K^{*}D^{(*)}$分子态。在高斯展开方法中,我们利用$\sigma$、$\rho$、$\omega$、$\pi$和$\eta$交换势求解薛定谔方程,系统性地包含了$S$波和更高分波。我们发现$D_{s1}(2700)$可以解释为一个纯$P$波$DK^{*}$分子,而$D_{s1}(2860)$和$D_{s3}(2860)$则被很好地描述为分别以$^{1}P_{1}$和$^{5}P_{3}$分量为主的$D^{*}K^{*}$分子态。我们还预言了具有各种$J^{P}$量子数的额外分子态。这些结果为粲-奇异谱提供了新的描述,并为重夸克味对称性破缺效应提供了有用的基准。
Motivated by the observed $KD^{(*)}$ molecular candidates $D_{s0}(2317)$ and $D_{s1}(2460)$, their bottom--strange counterparts, $K\bar{B}^{(*)}$ molecular states, are naturally expected, although not yet experimentally established. This discrepancy may reflect sizable heavy-quark flavor symmetry breaking, which introduces significant model uncertainties. Current studies of heavy-quark flavor symmetry breaking effects still exhibit strong parameter dependence, and further experimental input is required to constrain these effects, in particular regarding possible additional $K^{(*)}D^{(*)}$ and $K^{(*)}\bar{B}^{(*)}$ molecular states. In this work, we examine whether additional $K^{*}D^{(*)}$ molecular states can be identified among the observed $D_s$ resonances. Within the Gaussian expansion method, we solve the Schrödinger equation using $\sigma$, $\rho$, $\omega$, $\pi$, and $\eta$ exchange potentials, systematically including $S$-wave and higher partial waves. We find that $D_{s1}(2700)$ can be interpreted as a pure $P$-wave $DK^{*}$ molecule, while $D_{s1}(2860)$ and $D_{s3}(2860)$ are well described as $D^{*}K^{*}$ molecular states dominated by the $^{1}P_{1}$ and $^{5}P_{3}$ components, respectively. We also predict additional molecular states with various $J^{P}$ quantum numbers. These results provide a new description of the charmed--strange spectrum and a useful benchmark for heavy-quark flavor symmetry breaking effects.
为2.34米VBT望远镜设计的带非球面的三透镜宽场改正器
Nitish Singh, S. Sriram, Bharat Kumar Yerra
AI总结 针对2.34米VBT望远镜,设计了一种紧凑型三透镜宽场改正器,包含球面和非球面透镜,其中可移动透镜作为大气色散改正器,在0.4-0.9微米波段实现0.5度视场,D80优于0.3角秒。
我们正在为2.34米Vainu Bappu望远镜(VBT)开发一种紧凑的三元件宽场改正器(WFC),包含球面和非球面透镜,以增强其成像和光谱应用的视场覆盖。该设计由三个光学元件组成,其中至少一个球面透镜可移动,用作大气色散改正器(ADC),而非球面元件保持固定以维持光学稳定性。我们目前正在测试两种设计配置:一种包含两个球面透镜和一个非球面透镜,另一种包含两个非球面透镜和一个球面透镜。ADC设计用于校正天顶角从0度到60度范围内的大气色散。系统优化在0.4微米至0.9微米的波长范围内工作,目标有效视场约为0.5度。考虑到VBT主焦点有限的机械空间,设计强调紧凑性、易于对准和可制造性。系统在天顶时,设计1和设计2的平均D80分别优于0.3角秒和0.23角秒,并在大气色散校正后,在天顶角高达60度时,平均D80保持在0.57角秒和0.45角秒以内。通过使用可移动透镜元件,校正了较高天顶角(高达60度)的大气色散,使系统在整个视场内保持高图像质量。
We are developing a compact three-element Wide Field Corrector (WFC) with spherical and aspherical lenses for the 2.34 m Vainu Bappu Telescope (VBT) to enhance its field coverage for imaging and spectroscopic applications. The design consists of three optical elements, with at least one spherical lens movable to serve as an Atmospheric Dispersion Corrector (ADC), while the aspherical elements remain fixed to maintain optical stability. We are currently testing two design configurations, one with two spherical lenses and one aspherical lens, and another with two aspherical lenses and one spherical lens. The ADC is designed to correct atmospheric dispersion for zenith angles ranging from 0 degree to 60 degree. The system is optimized to operate over a wavelength range of 0.4 {\mu}m to 0.9 {\mu}m, targeting an effective field of view of about 0.5 degree. Considering the limited mechanical space available at the VBT prime focus, the design emphasizes compactness, ease of alignment, and manufacturability. The system achieves a mean D80 better than 0.3 arcsec and 0.23 arcsec for Design 1 and Design 2, respectively, at zenith, and maintains a mean D80 within 0.57 arcsec and 0.45 arcsec up to a zenith angle of 60 degree after atmospheric dispersion correction. Atmospheric dispersion at higher zenith angles (up to 60 degrees) is corrected using a movable lens element, enabling the system to preserve high image quality across the field.
重新审视稠密物质中的轴向反常和手征磁效应,及其对轴子暗物质的应用
Deog Ki Hong
AI总结 本文计算了稠密物质中的轴向反常,证明其形式与真空中相同,并重新审视了手征磁效应,发现介质支持由轴向化学势决定的持续反常电流,最后讨论了轴子暗物质作为有效轴向化学势的应用。
我们明确计算了稠密物质中的轴向反常,并证明即使在无质量极限下,其形式仍与真空中相同。这一结果源于反常Ward恒等式中介质对轴向流散度的贡献与赝标量密度的贡献之间的微妙抵消。然后,我们重新审视了在外磁场下与轴向化学势耦合的费米子介质中的手征磁效应。我们证明,该介质支持由费米子携带的持续、守恒的反常流。该电流由轴向化学势决定,并被费米速度抑制,这与反常轴向流关联函数一致。最后,我们讨论了在轴子物理学中的应用,其中轴子暗物质充当有效的轴向化学势。
We explicitly compute the axial anomaly in dense matter and show that its form remains unchanged from that in vacuum, even in the massless limit. This result follows from a subtle cancellation in the anomalous Ward identity between the medium-induced contributions to the divergence of the axial current and to the pseudoscalar density. We then revisit the chiral magnetic effect in a fermionic medium coupled to an axial chemical potential under an external magnetic field. We show that the medium supports a persistent, conserved anomalous current carried by fermions. The current is determined by the axial chemical potential and suppressed by the Fermi velocity, in agreement with anomalous axial-current correlation functions. We finally discuss applications to axion physics, where axion dark matter acts as an effective axial chemical potential.
偏心进动双黑洞旋进中的视界吸收及其对引力波数据分析的重要性
Alberto Álvaro-Díaz, Gonzalo Morras
AI总结 首次在领头阶后牛顿近似下推导了偏心且自旋进动双黑洞旋进中视界吸收的效应,并将其纳入波形模型。分析表明,该效应在特定系统(大自旋分量、极端质量比、长旋进)中显著,偏心轨道可打破简并,使其在高信噪比事件中可测量。
在双黑洞演化过程中,轨道运动与单个黑洞之间通过视界吸收交换能量和角动量,从而改变双星动力学以及黑洞的质量和自旋。这会在发射的引力波上留下印记,可能对当前和未来探测器观测到的信号的精确建模至关重要,同时也提供了探测致密天体本质的手段。在这项工作中,我们首次在后牛顿展开的领头阶推导了具有轨道偏心率和自旋引起的进动的双黑洞旋进中视界吸收的效应,并将这些修正纳入pyEFPEHM波形模型。然后,我们通过轨道去相位、波形失配和贝叶斯参数估计研究的解析估计来量化其影响。该效应对于具有与轨道角动量(反)对齐的大自旋分量($|\vec{\chi}_i \cdot \hat{l}| \sim 1$)、高度不等的质量比($q=m_2/m_1 \ll 1$)以及跨越宽频率范围的长旋进($\log(f_\mathrm{max}/f_\mathrm{min}) \gg 1$)的系统最大。对于此类系统,忽略视界吸收会在中等信噪比下导致恢复的双星参数出现偏差。在准圆形双星中,这些偏差在很大程度上吸收了该效应,使其难以探测。然而,在偏心双星中,更丰富的信号形态打破了这种简并,使得视界吸收在高信噪比事件中可能被测量到。
During the evolution of a binary black hole, energy and angular momentum are exchanged between the orbital motion and the individual black holes through horizon absorption, modifying both the binary dynamics and the black hole masses and spins. This leaves an imprint on the emitted gravitational waves that may be relevant for the accurate modeling of signals observed by current and future detectors, while also offering a probe of the nature of compact objects. In this work, we derive, for the first time and at leading order in the post-Newtonian expansion, the effect of horizon absorption in binary black hole inspirals with both orbital eccentricity and spin-induced precession, and we incorporate these corrections into the pyEFPEHM waveform model. We then quantify their impact through analytical estimates of the orbital dephasing, waveform mismatches, and Bayesian parameter-estimation studies. The effect is largest for systems with large spin components (anti-)aligned with the orbital angular momentum ($|\vec{\chi}_i \cdot \hat{l}| \sim 1$), highly unequal mass ratios ($q=m_2/m_1 \ll 1$), and long inspirals spanning a wide frequency range ($\log(f_\mathrm{max}/f_\mathrm{min}) \gg 1$). For such systems, neglecting horizon absorption biases the recovered binary parameters at moderate signal-to-noise ratios. In quasi-circular binaries these biases largely absorb the effect, rendering it difficult to detect. In eccentric binaries, however, the richer signal morphology breaks this degeneracy, making horizon absorption potentially measurable in high signal-to-noise-ratio events.
基于非线性波神经元的集成磁振子神经电路
Mengying Guo, Xudong Jing, Kristýna Davidkova, Roman Verba, Zhenyu Zhou, Xueyu Guo, Carsten Dubs, Chuan Gao, Yiheng Rao, Kaiming Cai, Jing Li, Philipp Pirro, Andrii V. Chumak, Qi Wang
AI总结 本文利用纳米钇铁石榴石波导中的非线性阈值神经元实现集成磁振子神经电路,通过泵浦控制非线性激活和自归一化输出,实现确定性级联和可重构模式识别。
人工智能正推动对能够进行神经信息处理的替代计算硬件的强烈兴趣,超越传统的基于电荷的电子学。在新兴方法中,基于波的计算有望实现高度并行和节能的操作,但可扩展的物理神经硬件仍然难以实现,因为波系统通常缺乏具有信号再生和相位鲁棒操作的可级联非线性神经元。在这里,我们展示了基于非线性阈值神经元的集成磁振子神经电路,这些神经元在纳米尺度的钇铁石榴石波导中实现。神经元对多个自旋波输入进行加权求和,而泵浦控制的非线性激活定义了连续可调的触发阈值。由于深度非线性的自旋波动力学,激活的神经元发射自归一化输出,其强度在很大程度上独立于输入幅度,而非线性相位自调整抑制了对相对输入相位的敏感性,从而实现了无需外部信号恢复的确定性神经元间级联。我们实验实现了可编程阈值神经元、可重构加权分类以及连续神经元阶段之间的确定性级联,并进一步通过实验分类二进制字母模式'HUST',在七神经元集成磁振子电路中展示了可重构的物理模式识别。这些结果确立了非线性磁振子作为集成神经硬件的可扩展平台,并将非线性波动力学定位为物理神经形态计算的一般范式。
Artificial intelligence is driving intense interest in alternative computing hardware capable of neural information processing beyond conventional charge-based electronics. Among emerging approaches, wave-based computing promises highly parallel and energy-efficient operation, but scalable physical neural hardware has remained elusive because wave systems generally lack cascadable nonlinear neurons with signal regeneration and phase-robust operation. Here we demonstrate integrated magnonic neural circuits based on nonlinear threshold neurons realized in nanoscale yttrium iron garnet waveguides. The neurons perform weighted summation of multiple spin-wave inputs, while a pump-controlled nonlinear activation defines continuously tunable firing thresholds. Owing to deeply nonlinear spin-wave dynamics, the activated neurons emit self-normalized outputs whose intensities are largely independent of the input amplitudes, while nonlinear phase self-adjustment suppresses sensitivity to the relative input phases, enabling deterministic neuron-to-neuron cascading without external signal restoration. We experimentally realize programmable threshold neurons, reconfigurable weighted classification and deterministic cascading between sequential neuronal stages, and further demonstrate reconfigurable physical pattern recognition in a seven-neuron integrated magnonic circuit through experimental classification of the binary letter patterns 'HUST'. These results establish nonlinear magnons as a scalable platform for integrated neural hardware and position nonlinear wave dynamics as a general paradigm for physical neuromorphic computing.
超晶格中相干调制的声子带和寿命的观测
Yuxuan Liao, Hiroshi Uchiyama, Naomi Nagai, Natalia Morais, Taiushun Manjo, Rulei Guo, Harsh Chandra, Ryohei Nagahiro, Bin Xu, Hiroshi Fukui, Daisuke Ishikawa, Alfred Q.R. Baron, Yasuhiko Arakawa, Kazuhiko Hirakawa, Junichiro Shiomi
AI总结 利用高分辨率非弹性X射线散射,在短周期GaAs/AlAs超晶格中观测到相干调制的声子带结构和声子带隙,首次直接证明室温及以上温度的声子相干性,并揭示其对三声子散射和光学声子软化的增强作用。
类似于基本粒子(如光子和电子)的行为,人工周期纳米结构中的声子波干涉会相干调制声子能带结构,成为声子能带工程的基础。然而,尽管现有文献提供了大量见解,直接观测这种相干调制的声子能带结构仍然具有挑战性。在这里,利用高分辨率非弹性X射线散射,我们在300 K和500 K的短周期GaAs/AlAs超晶格中观测到了具有声子带隙的相干调制声子能带结构。我们的发现首次直接证明了室温及以上温度的声子相干性,标志着声子能带结构人工工程的重大进展。此外,我们的实验观测和从头算晶格动力学表明,相干调制的声子能带结构增强了三声子散射通道,加强了高阶非谐效应,如三声子散射和光学声子软化。我们的观测证明了高温下声子相干性的鲁棒性,并通过采用灵活的自下而上纳米结构方法,为工程化声子能带结构和高阶声子-声子散射开辟了新途径,在声子超材料、微电子学和热电学中具有广泛应用。
Similar to the behavior of elementary particles, such as photons and electrons, the interference of phonon waves in artificial periodic nanostructures coherently modulates phonon band structures, serving as the foundation for phonon band engineering. However, direct observation of such coherently modulated phonon band structures remains challenging despite substantial insights from existing literature. Here, utilizing high-resolution inelastic X-ray scattering, we observed coherently modulated phonon band structures with phononic band gaps in a short-period GaAs/AlAs superlattice at 300 K and 500 K. Our findings provide the first direct evidence of phonon coherence at and above room temperatures, signifying a major advancement in the artificial engineering of phonon band structures. Furthermore, our experimental observations and ab initio lattice dynamics revealed that the coherently modulated phonon band structure enhances three-phonon scattering channels, strengthening high-order anharmonic effects such as three-phonon scattering and optical phonon softening. Our observations demonstrate the robustness of phonon coherence at high temperatures, and opens new routes for engineering phonon band structure and high-order phonon-phonon scattering by employing a flexible, bottom-up nanostructuring approach, with extensive applications in phononic metamaterials, microelectronics, and thermoelectrics.
谱正则化潜流匹配用于湍流生成
Khalid Rafiq, Aditya G. Nair
发表机构 * Department of Mechanical Engineering, University of Nevada, Reno(内华达大学里诺分校机械工程系)
AI总结 针对潜扩散和流匹配模型在湍流生成中低估耗散区振幅的问题,提出谱正则化潜流匹配框架,通过区域加权对数谱目标将深度耗散保留谱功率从25%提升至94%,并显著改善采样成本-保真度权衡。
潜扩散和流匹配已成为合成湍流生成的主要方法,但它们系统性地低估了耗散范围的振幅。我们引入了一个潜流匹配框架,其中包含一个直接针对此失效模式的谱正则化压缩阶段。在Re_f ≈ 2250的256^2 DNS数据集上,将MSE训练的VAE替换为区域加权对数谱目标,在重建中将深度耗散保留谱功率从25%提升至94%,在无条件生成中从20%提升至79%。改进的潜表示还产生了显著更好的采样成本-保真度权衡:MSE训练的潜空间在DD偏差-0.70附近施加了一个基本质量上限,任何积分器或步数都无法克服,而谱正则化的潜空间在仅20次函数评估时就达到了DD偏差-0.117。从机制上讲,编码器-解码器交换实验表明,改进主要由编码器诱导的潜重组驱动,而非解码器容量;而支持-振幅分解揭示,MSE训练的模型表现为保守抑制模型,通过衰减间歇性高波数结构来最小化逐点误差。两种管道都恢复了二阶结构函数和S_3的正确符号,表明在没有显式监督的情况下正确的级联方向。S_3幅度上的一个小残余差距表明,相位相干三元组组织仍然是未来生成湍流模型中振幅保真度的补充轴。
Latent diffusion and flow matching have emerged as leading approaches for synthetic turbulence generation, yet they systematically under-represent dissipation-range amplitudes. We introduce a latent flow matching framework with a spectrally regularized compression stage that directly targets this failure mode. On a 256^2 DNS dataset at Re_f \approx 2250, replacing an MSE-trained VAE with a zone-weighted log-spectral objective raises deep-dissipation retained spectral power from 25% to 94% in reconstruction and from 20% to 79% in unconditional generation. The improved latent representation also yields a substantially better sampling cost-fidelity tradeoff: the MSE-trained latent space imposes a fundamental quality ceiling near DD bias -0.70 that no integrator or step-count can overcome, while the spectrally regularized latent space reaches DD bias -0.117 at just 20 function evaluations. Mechanistically, encoder-decoder swap experiments show that the improvement is driven primarily by encoder-induced latent reorganization rather than decoder capacity, while a support-amplitude decomposition reveals that MSE-trained models behave as conservative suppression models, minimizing pointwise error by attenuating intermittent high-wavenumber structure. Both pipelines recover the second-order structure function and the correct sign of S_3, indicating the correct cascade direction without explicit supervision. A small residual gap in the magnitude of S_3 suggests that phase-coherent triadic organization remains a complementary axis to amplitude fidelity for future generative turbulence models.
DSpinGNN:一种用于应变变形单层CrI$_3$中动态磁交换预测的物理信息等变图神经网络
Isam A. Balghari, M. Faryad, M. Sabieh Anwar
AI总结 提出DSpinGNN,结合E(3)-等变图神经网络和物理信息Δ-MLP,预测动态变形晶格中的各向同性磁交换耦合,在单层CrI$_3$上实现高精度,并揭示应变波引起的交换耦合纹理。
解析动态变形晶格中瞬态、位置依赖的各向同性磁交换耦合$J_{ij}$需要一种计算方法,该方法能同时处理结构力和磁相互作用,且尺度达到第一性原理方法无法企及。本文介绍DSpinGNN,一种分叉机器学习架构,包含用于经典朗之万结构动力学的$E(3)$-等变图神经网络(E-GNN)和将瞬态局部Cr-I-Cr键几何映射到各向同性交换耦合的物理信息$\Delta$-MLP,其中Goodenough-Kanamori超交换关系作为分析归纳偏置嵌入。在单层CrI$_3$的345个DFT+U构型上训练,并在严格保留的61构型测试集上评估,DSpinGNN同时实现了能量MAE为$1.1$ meV/原子、力MAE为$6.5$ meV/Å和交换耦合MAE为$0.18$ meV($R^2 = 0.91$)。在$5$ K下,以共线伊辛约束绝热近似部署于3200原子超胞(400倍尺度),模型将局部交换响应映射到传播的双轴应变波。周期性边界处的波反射产生瞬态相长干涉区域,其中局部压缩应变超过DFT建立的铁磁-反铁磁阈值,产生空间异质交换耦合纹理,并随波耗散而衰减。定量分析得到畴壁宽度$\xi = 1.7 \pm 0.3$~nm和相长干涉振荡周期$\tau = 0.27$~ps——这些介观可观测量直接DFT无法获得,构成低温磁力显微镜的可检验预测。DSpinGNN为应变驱动二维磁性材料中的介观交换映射提供了可重复、可迁移的框架。
Resolving the instantaneous, position-dependent isotropic magnetic exchange coupling $J_{ij}$ across a dynamically deforming crystal lattice requires a computational approach that simultaneously handles structural forces and magnetic interactions at length scales inaccessible to first-principles methods. Here we introduce DSpinGNN, a bifurcated machine-learning architecture comprising an $E(3)$-equivariant graph neural network (E-GNN) for classical Langevin structural dynamics and a physics-informed $\Delta$-MLP that maps instantaneous local Cr-I-Cr bond geometry to isotropic exchange couplings, with the Goodenough-Kanamori superexchange relationship embedded as an analytical inductive bias. Trained on 345 DFT+U configurations of monolayer CrI$_3$ and evaluated on a strictly withheld 61-configuration test set, DSpinGNN simultaneously achieves an energy MAE of $1.1$ meV/atom, a force MAE of $6.5$ meV/Å, and an exchange coupling MAE of $0.18$ meV ($R^2 = 0.91$). Deployed at 400$\times$ scale in a 3,200-atom supercell under a collinear Ising-constrained adiabatic approximation at $5$ K, the model maps the local exchange response to a propagating biaxial strain wave. Wave reflection at periodic boundaries generates transient constructive interference regions where local compressive strain exceeds the DFT-established FM-to-AFM threshold, producing spatially heterogeneous exchange coupling textures that damp as the wave dissipates. Quantitative analysis yields a domain wall width of $\xi = 1.7 \pm 0.3$~nm and a constructive-interference oscillation period of $\tau = 0.27$~ps -- mesoscopic observables inaccessible to direct DFT and constituting testable predictions for cryogenic magnetic force microscopy. DSpinGNN provides a reproducible, transferable framework for mesoscale exchange mapping in strain-driven 2D magnetic materials.
布洛赫表示中涉及位置算符的算符一致评估:应用于轨道矩
Daehyeon An, Junmo Jeon, Se Kwon Kim
AI总结 提出三条规则和规范过滤方案,解决布洛赫表示中位置算符相关算符评估的不一致问题,并应用于波包自旋和万尼尔函数局域环流的统一。
位置算符在凝聚态物理可观测量(如速度、轨道矩和电极化)中扮演核心角色。在固体物理中,涉及位置算符的算符评估尚未达成共识,正如在万尼尔函数的局域环流与波包自旋之间的算符级别差异所观察到的。为了实现对这类算符的一致评估,我们提出了在布洛赫表示中评估涉及位置算符的算符的三条规则。这些规则旨在满足物理条件:独立于原胞的选择、保持算符乘积的厄米共轭性,以及恢复正确的带内速度。我们进一步处理了位置算符的规范依赖性,并引入了一种称为规范过滤的方案,该方案系统地移除包含位置算符的算符中的规范依赖贡献。该方法确保从算符评估中获得的量对应于可观测的物理现象。通过应用我们的框架,我们调和了关于波包自旋和万尼尔函数局域环流的结果。我们期望我们的提议能够为涉及位置算符的算符评估建立一个一致的框架。
The position operator plays a central role in condensed-matter observables such as velocity, orbital moment, and electric polarization. In solid-state physics, the evaluation of operators incorporating the position operator has not reached a consensus, as observed in the operator-level discrepancy between the local circulation of Wannier functions and the self-rotation of wave packets. Here, to achieve a consistent evaluation of such operators, we propose three rules for evaluating operators involving the position operator in the Bloch representation. The rules are devised to satisfy physical conditions: independence from the choice of unit cell, preservation of Hermitian conjugacy for the product of operators, and recovery of the correct intraband velocity. We further address the gauge dependence of the position operator and introduce a scheme termed gauge filtration, which systematically removes gauge-dependent contributions from the operators containing the position operator. This methodology ensures that the quantities obtained from the operator evaluation correspond to observable physical phenomena. By applying our framework, we reconcile the results concerning the self-rotation of the wave packet and the local circulation of the Wannier function. We expect our proposal to establish a consistent framework for evaluating operators involving the position operator.
神经参数化元胞自动机用于野火蔓延
Maksym Zhenirovskyy, Ion Matei, Rohit Vuppala, Takuya Kurihana, Hon Yung Wonga
AI总结 提出一种混合深度学习参数化概率元胞自动机框架,利用多尺度卷积神经网络动态生成空间变化参数,在保持物理可解释性的同时捕捉复杂环境交互,在六次大型野火中实现72小时IoU>0.6的预测。
传统野火模型依赖刚性、低维参数和静态燃料图,常常低估火势蔓延。为解决这一弱点,我们引入了一个在JAX中实现的混合深度学习参数化概率元胞自动机(CA)框架。我们的方法采用多尺度卷积神经网络动态生成控制火势蔓延概率、风向对齐和坡度影响的空间变化参数。这种混合设计捕捉了复杂的非线性环境交互,同时保留了底层三态CA的物理可解释性。JAX实现支持硬件加速和基于梯度的参数校准。在美国西部六次大规模野火上的评估显示,在10天数据同化窗口期间模型逐步拟合观测到的火线后,该模型在72小时预测范围内保持IoU>0.6;由此产生的预测是在这些观测中已编码的抑制机制下火势增长的条件投影。
Traditional wildfire models rely on rigid, low-dimensional parameters and static fuel maps, frequently underpredicting fire spread. To address this weakness, we introduce a hybrid deep-learning parameterized Probabilistic Cellular Automata (CA) framework implemented in JAX. Our approach employs a Multi-Scale Convolutional Neural Network to dynamically generate spatially varying parameters that govern fire-spread probability, wind alignment, and slope influence. This hybrid design captures complex, nonlinear environmental interactions while preserving the physical interpretability of the underlying three-state CA. The JAX implementation enables hardware acceleration and gradient-based parameter calibration. Evaluated on six large-scale wildfires in the western United States, the model maintains IoU > 0.6 over 72-hour forecast horizons after a 10-day data assimilation window during which the model is fitted incrementally to observed perimeters; the resulting forecast is a conditional projection of fire growth under the suppression regime already ncoded in those observations.
高阶令牌交互的量子注意力机制
Jian Xu, Chao Li, Delu Zeng, John Paisley, Qibin Zhao
AI总结 提出量子高阶注意力(QHA),通过数据重上传和非克利福德纠缠器在浅电路中合成任意阶令牌交互,证明其表达能力超越经典自注意力,并具有可训练性保证,在遗传上位、带噪学习奇偶和图三角形检测中高效检测高阶交互。
标准点积自注意力在单层中仅计算令牌间的成对(二阶)交互;表示一般的$k$阶交互已知需要在单层中使用超二次资源或通过深度组合。我们引入\textbf{量子高阶注意力(QHA)},一种浅层、硬件可实现的量子注意力头,通过数据重上传和全对非克利福德纠缠器,在电路内部合成$k$阶令牌交互,并通过局部单量子比特读出暴露它们。我们证明:(i)表达能力分离:任何嵌入维度$m$、$H$个头和$p$位精度满足$mHp=o(N/\log\log N)$的单个标准自注意力层无法表示一个QHA头以电路深度$O(\log k)$($O(k)$个两量子比特门)表示的$k$阶相关族;(ii)其局部设计实例的可训练性保证:使用局部读出和$O(\log n)$深度,梯度方差为$\Omega(1/\mathrm{poly}(n))$(无贫瘠高原),我们通过实验确认——同时明确我们基准测试的更具表达力的全对实例是经验训练的,并显示指数衰减的梯度。实验上,在参数预算小$6.5\times$的情况下,QHA从不相交输入中泛化每个阶$k\le6$的隐藏子集奇偶性,而更大的经典注意力头在阶~2之后崩溃;与理论一致,优势的大小跟踪目标的傅里叶度——奇偶性最大,当存在低阶结构时缩小。作为一个应用,QHA在三个领域——遗传上位、带噪学习奇偶和图三角形检测——作为紧凑的高阶交互检测器,在最小的参数预算下达到噪声上限,而领域标准的线性方法失败。
Standard dot-product self-attention computes, in a single layer, only pairwise (order-2) interactions between tokens; representing a generic order-$k$ interaction is known to require either super-quadratic resources in one layer or composition across depth. We introduce \textbf{Quantum Higher-Order Attention (QHA)}, a shallow, hardware-realizable quantum attention head that, via data re-uploading and an all-to-all non-Clifford entangler, synthesizes order-$k$ token interactions inside the circuit and exposes them through a local single-qubit read-out. We prove (i) an expressivity separation: any single standard self-attention layer with embedding dimension $m$, $H$ heads and $p$-bit precision satisfying $mHp=o(N/\log\log N)$ cannot represent the order-$k$ correlation family that one QHA head represents with circuit depth $O(\log k)$ ($O(k)$ two-qubit gates); and (ii) a trainability guarantee for its local-design instantiation: with a local read-out and $O(\log n)$ depth the gradient variance is $\Omega(1/\mathrm{poly}(n))$ (no barren plateau), which we confirm empirically -- while being explicit that the more expressive all-to-all instantiation we benchmark is trained empirically and shows exponentially decaying gradients. Empirically, at a $6.5\times$ smaller parameter budget, QHA generalizes hidden-subset parity of every order $k\le6$ from disjoint inputs, whereas the larger classical attention head collapses past order~2; consistent with theory, the size of the advantage tracks the target's Fourier degree - largest for parity and shrinking when low-order structure is present. As an application, QHA serves as a compact high-order interaction detector across three domains - genetic epistasis, learning-parity-with-noise, and graph triangle detection - reaching the noise ceiling at the smallest parameter budget where field-standard linear methods fail.
Skyrme Hartree-Fock-Bogoliubov理论在40Ar中WIMP-核相互作用中的应用
N. Krishnan, R. Abdel Khaleq, C. Simenel
AI总结 采用自洽Skyrme Hartree-Fock-Bogoliubov方法研究40Ar的WIMP散射,计算暗物质直接探测相关的核形状因子,并与壳模型预测比较,发现自旋无关响应吻合良好,自旋-轨道响应因单粒子占据数差异而显著不同。
使用自洽的Skyrme Hartree-Fock-Bogoliubov (HFB)方法研究了40Ar的WIMP散射。从得到的单体密度矩阵元素计算了与暗物质直接探测相关的核形状因子,并与壳模型预测进行了比较。自旋无关响应吻合良好,而由于单粒子占据数的变化,自旋-轨道响应观察到显著差异。粒子数投影对40Ar的影响很小。这些结果表明某些暗物质响应通道对底层核结构模型的敏感性,并建立了将平均场计算扩展到超出大规模壳模型研究范围的原子核的框架。
WIMP scattering from 40Ar is investigated using a self-consistent Skyrme Hartree-Fock-Bogoliubov (HFB) approach. Nuclear form factors relevant to dark matter direct detection are calculated from the resulting one-body density matrix elements and compared with shell-model predictions. Good agreement is found for the spin-independent response, while significant differences are observed for the spin-orbit response due to variations in single-particle occupancies. The effects of particle-number projection are shown to be small for 40Ar. These results demonstrate the sensitivity of certain dark matter response channels to the underlying nuclear structure model and establish a framework for extending mean-field calculations to nuclei beyond the reach of large-scale shell-model studies.
通过超精细中间态实现快速绝热量子门
Jiayin Fan, Xingdong Zhao, Manqi Zhang, Fangfang Xie, Jing Qian
AI总结 提出基于电磁诱导透明的绝热CNOT门协议,利用原子超精细中间态加速绝热演化,在铯原子系统中实现0.3903微秒内保真度超过0.9991的快速绝热量子门。
绝热量子计算的吸引力在于其内在对各种技术缺陷的鲁棒性,使其在众多量子信息应用中具有吸引力。然而,它面临一个基本挑战:在量子比特相干时间内保持绝热性的同时加速绝热操作。在本文中,我们提出了一种基于电磁诱导透明的绝热CNOT门协议,该协议利用原子超精细中间态(HIS)来加速绝热演化。超精细中间态自然存在于双光子跃迁中,通常由于其显著的衰变误差而被抑制。相反,本文引入了一种新方法,利用适当选择的超精细中间态不仅增强STAY路径中的绝热性,还加速TRANSFER路径中的布居转移。通过脉冲优化,我们在实际的铯原子系统中实现了在0.3903微秒内绝热门保真度超过0.9991。为了证明协议的通用性,我们进一步评估了多个超精细中间态衰变的影响,并将模型扩展到任意数量的状态,为在里德伯原子平台上实现快速且鲁棒的绝热量子门提供了一条实用途径。
The appeal of adiabatic quantum computing lies in its intrinsic robustness against various technical imperfections, making it attractive for many quantum information applications. However, it faces a fundamental challenge: accelerating the adiabatic operations while preserving adiabaticity within the qubit coherence time. In this article, we propose an electromagnetically induced transparency-based adiabatic CNOT gate protocol which harnesses atomic hyperfine intermediate states (HISs) to speed up the adiabatic evolution. The HISs, naturally-existed in two-photon transitions, often need to be suppressed due to their significant decay errors. In contrast, this paper introduces a novel method that utilizes appropriately chosen HISs not only to enhance the adiabaticity in STAY pathway but also to accelerate the population transfer in TRANSFER pathway. Through pulse optimization, we achieve adiabatic gate fidelities exceeding 0.9991 within 0.3903 {\mu}s in realistic Cs atomic setups. To demonstrate the generality of protocol we further assess the impact of decays from multiple HIS and extend our model to arbitrary number of states, providing a practical route toward fast and robust adiabatic quantum gates in Rydberg-atom platforms.
关于红树林水动力阻力的建模
Khang Ee Pang, Zhi Yung Tay
AI总结 提出一种适用于多种红树林物种的植被剖面参数化方法,并建立考虑根系特征的波浪衰减模型,发现红树林的波浪衰减效果具有频率选择性和物种依赖性。
红树林作为基于自然的海岸保护解决方案日益受到推广,然而许多现有模型忽略了植被生物量的垂直变化,导致对根系-流动相互作用的过度简化。在本研究中,我们引入了一种适用于多种红树林物种的植被剖面广义参数化方法,并推导出一个明确考虑红树林根系特征的波浪衰减模型。基于该参数化方法,我们提出了一种简化的红树林表示,该表示能够再现预设的阻力剖面,并适用于计算流体动力学模拟和实验制造。使用OpenFOAM模拟评估了所提出模型的水动力性能。我们的结果表明,红树林的波浪衰减效果具有频率选择性和物种依赖性。这种非线性行为与经典植被模型形成对比,揭示了一种先前未被认识的机制,即红树林根系特征控制着海岸保护。
Mangroves are increasingly promoted as nature-based solutions for coastal protection, yet many existing models neglect the vertical variation of vegetation biomass, leading to oversimplified representations of root-flow interactions. In this study, we introduce a generalised parametrisation of the mangrove vegetation profile that is applicable across multiple mangrove species and derive a wave attenuation model that explicitly accounts for the mangrove root characteristics. Based on this parametrisation, we propose a simplified mangrove representation that reproduces a prescribed drag force profile and is suitable for both computational fluid dynamics simulations and experimental fabrication. The hydrodynamic performance of the proposed model is evaluated using OpenFOAM simulations. Our results show that the wave attenuation effectiveness of mangroves is frequency-selective and species dependent. This nonlinear behaviour contrasts with classical vegetation models and reveals a previously unrecognized mechanism by which mangrove root characteristics govern coastal protection.
具有可处理不确定性量化的保结构神经代理模型
Handi Zhang, Adrienne M. Propp, Brooks Kinch, Houman Owhadi, Nathaniel Trask
发表机构 * University of Pennsylvania(宾夕法尼亚大学) ; Stanford University(斯坦福大学) ; California Institute of Technology(加州理工学院)
AI总结 提出一种结合混合有限元空间与高斯过程回归的保结构降阶模型,通过拓扑结构实现状态-通量关系的不确定性量化,并导出狄利克雷-诺伊曼映射的闭式后验不确定性。
科学机器学习的最新进展为偏微分方程(PDE)的近实时求解提供了一种手段,但缺乏支持当代验证与确认的传统模拟器的理论基础。在这项工作中,我们构建了数据驱动的降阶模型,作为保结构、实时代理模型。值得注意的是,施加物理守恒结构的外微分也揭示了拓扑结构,我们利用该结构构建了状态-通量关系中不确定性的高斯过程(GP)表示,最终为目标量导出具有后验不确定性闭式表达的狄利克雷-诺伊曼映射。我们特别提出了由轻量级变压器规定的传统Raviart-Thomas和$dgP_0$单元的保结构$H(\mathrm{div})$--$L^2$子空间。通过提出一个守恒律来学习与该子空间一致的降阶动力学,其中GP描述了体积之间的通量。这项工作依赖于混合有限元空间与GP回归之间的新颖接口;当训练被表述为最优恢复问题(ORP)时,得到的GP回归可以写成一个带有等式约束的优化问题,该约束施加了守恒结构,适用于快速的Schur补训练策略。然后,训练好的模型可以实时求解,得到由指定狄利克雷数据驱动的边界通量的闭式估计量。本文包括线性泛函的RKHS后验误差界以支持不确定性量化,以及数值实验证明了后验分布作为误差估计代理的准确性。
Recent advances in scientific machine learning provide a means of near-real-time solution to partial differential equations (PDEs), but lack the theoretical underpinnings of conventional simulators that support contemporary verification and validation. In this work, we construct data-driven reduced-order models that serve as structure-preserving, real-time surrogates. Remarkably, the exterior calculus that imposes physical conservation structure also exposes topological structure that we use to build a Gaussian process (GP) representation of uncertainty in state-flux relationships, ultimately yielding a Dirichlet-to-Neumann map for quantities of interest with closed-form expressions for posterior uncertainty. We specifically propose structure-preserving $H(\mathrm{div})$--$L^2$ subspaces of conventional Raviart--Thomas and $dgP_0$ elements prescribed by a lightweight transformer. Reduced-order dynamics consistent with this subspace are learned by posing a conservation law in which a GP describes the fluxes between volumes. This work hinges on a novel interface between mixed FEM spaces and GP regression; when training is posed as the optimal recovery problem (ORP), the resulting GP regression can be written as an optimization problem with equality constraints that impose a conservation structure, amenable to a fast Schur-complement training strategy. The trained model can then be solved in real time with closed-form estimators for boundary fluxes driven by prescribed Dirichlet data. The paper includes RKHS posterior error bounds for linear functionals to support uncertainty quantification, as well as numerical experiments demonstrating the accuracy of the posterior distribution as a surrogate for error estimation.
水/ITO界面上的体上DC克尔电光效应,通过普克尔斯效应解析
Soichiro Ashikaga, Kazuaki Nakata, Akihiro Okada, Takumi Takayanagi, Kyohei Yamashita, Takayoshi Kobayashi, Eiji Tokunaga
AI总结 本文通过AC+DC调制方法,同时参数化水/ITO界面的普克尔斯和DC克尔效应,发现界面DC克尔系数比体水高数倍,且为界面特异性可调性质。
在带电界面上,反演对称性破缺允许通过$\chi^{(2)}(\omega;\omega,0)$产生大的场线性普克尔斯响应;在水/ITO界面,$|r_{13}|$已被报道达到$10^{2}\\,\mathrm{pm/V}$量级。共存的第三阶DC克尔项$\chi^{(3)}(\omega;\omega,0,0)$——在体水中很小($|\chi^{(3)}_{\mathrm{bulk}}|\sim5.5\times10^{-21}\\,\mathrm{m^2/V^2}$)——尚未与普克尔斯项沿基频($\omega$)电光路径联合参数化。在0.1\\,M NaCl中叠加交流调制和直流偏置,通过交叉项$2 s_{1133}\\,E_{\mathrm{DC}}$将$\chi^{(3)}$贡献与1f响应混合,使得水的折射率调制$\Delta n_{\mathrm{water}}$随$V_{\mathrm{WE}}$线性变化;模型辅助的线性拟合随后从单次AC$+$DC扫描中确定两项。在$V_{\mathrm{WE}}=0\\,\mathrm{V}$(相对于Ag/AgCl)时,$|r_{13}|=(1.18 \pm 0.06_{\mathrm{PZC}})\times10^{2}\\,\mathrm{pm/V}$,且在$\eta_{\mathrm{DC}}=1$下,厚度归一化的DC克尔系数$|s_{1133}/d_{\mathrm{EDL}}|=33.0 \pm 5.6\\,\mathrm{pm/V^{2}}$。在物理合理的$d_{\mathrm{EDL}}$($0.6$--$1.6\\,\mathrm{nm}$)范围内,界面DC克尔磁化率达到$|\chi^{(3),\mathrm{int}}_{1133}| \approx (2\text{--}5.5)\times10^{-20}\\,\mathrm{m^2/V^2}$,比可见光范围内体水值高出数倍。该响应是特定界面的性质,可通过电极、电解质和溶剂的选择而非体水固有性质进行调节。在对水的克尔响应重新产生兴趣的背景下(包括近期太赫兹波段光学克尔研究),该方法直接探测了沿$\omega$路径的DC克尔项,并补充了SHG/SFG($2\omega$路径)。
On a charged interface, broken inversion symmetry permits a large field-linear Pockels response through $\chi^{(2)}(\omega;\omega,0)$; at the water/ITO interface $|r_{13}|$ has been reported to reach the $10^{2}\,\mathrm{pm/V}$ order. The coexisting third-order DC Kerr term $\chi^{(3)}(\omega;\omega,0,0)$ -- small in bulk water ($|\chi^{(3)}_{\mathrm{bulk}}|\sim5.5\times10^{-21}\,\mathrm{m^2/V^2}$) -- had not been jointly parameterized with the Pockels term along the fundamental-frequency ($\omega$) electro-optic path. Superimposing an AC modulation and a DC bias in 0.1\,M NaCl mixes the $\chi^{(3)}$ contribution with the 1f response through the cross-term $2 s_{1133}\,E_{\mathrm{DC}}$, so that the water refractive-index modulation $\Delta n_{\mathrm{water}}$ varies linearly with $V_{\mathrm{WE}}$; a model-assisted linear fit then determines both terms from a single AC$+$DC sweep. At $V_{\mathrm{WE}}=0\,\mathrm{V}$ vs Ag/AgCl, $|r_{13}|=(1.18 \pm 0.06_{\mathrm{PZC}})\times10^{2}\,\mathrm{pm/V}$ and, under $\eta_{\mathrm{DC}}=1$, the thickness-normalized DC Kerr coefficient $|s_{1133}/d_{\mathrm{EDL}}|=33.0 \pm 5.6\,\mathrm{pm/V^{2}}$. Across physically reasonable $d_{\mathrm{EDL}}$ ($0.6$--$1.6\,\mathrm{nm}$), the interfacial DC Kerr susceptibility reaches $|\chi^{(3),\mathrm{int}}_{1133}| \approx (2\text{--}5.5)\times10^{-20}\,\mathrm{m^2/V^2}$, several-fold above the visible-range bulk-water value. This response is a property of the specific interface, tunable through the choice of electrode, electrolyte, and solvent rather than intrinsic to bulk water. Amid renewed interest in the Kerr response of water (including recent THz-band optical Kerr studies), the method directly probes this DC Kerr term along the $\omega$ path and complements SHG/SFG (the $2\omega$ path).