Exact Single-Scale Outer Solution of the Abrikosov Vortex in the Extreme Type-II Limit
极端第二类极限下阿布里科索夫涡旋的精确单尺度外解
AI总结 在Ginzburg-Landau参数κ发散时,通过求解超流速度的非线性理论,得到了极端第二类极限下阿布里科索夫涡旋的精确外结构,证明磁场和超导密度均在伦敦穿透深度尺度上变化,推翻了传统的双尺度图像。
极端第二类极限下阿布里科索夫涡旋的精确单尺度外解
Eugene B. Kolomeisky
AI总结 在Ginzburg-Landau参数κ发散时,通过求解超流速度的非线性理论,得到了极端第二类极限下阿布里科索夫涡旋的精确外结构,证明磁场和超导密度均在伦敦穿透深度尺度上变化,推翻了传统的双尺度图像。
我们确定了极端第二类极限下阿布里科索夫涡旋的精确外结构,该极限发生在Ginzburg-Landau参数$κ$发散时。在此极限下,Ginzburg-Landau理论在缩小的核心外部简化为一个封闭的非线性理论,描述超流速度并受代数密度约束。所得解在消失的涡旋核心外部处处渐近精确,证明磁场和超导密度均在伦敦穿透深度的长度尺度上变化。这确立了传统的涡旋双尺度图像在$κ\gg 1$极限下不成立。
We determine the exact outer structure of the Abrikosov vortex in the extreme type-II limit, which occurs when the Ginzburg-Landau parameter $κ$ diverges. In this limit, Ginzburg-Landau theory simplifies, outside a shrinking core, to a closed nonlinear theory for the superfluid velocity subject to an algebraic density constraint. The resulting solution is asymptotically exact everywhere outside the vanishing vortex core, demonstrating that both magnetic field and superconducting density vary on the length scale of the London penetration depth. This establishes that the conventional two-length-scale picture of the vortex does not hold in the $κ\gg 1$ limit.
MeerKAT大质量遥远星系团巡天:在30个$z>1$的大质量SZ选星系团中搜寻弥漫射电辐射
Dakalo G. Phuravhathu, M. Hilton, S. P. Sikhosana, D. Y. Klutse, K. Knowles, J. van Marrewijk, K. Moodley, T. Mroczkowski, N. Oozeer, B. Partridge, Y. C. Perrott, C. Sifón, U. Sureshkumar
AI总结 利用MeerKAT 1.28 GHz观测,在30个红移$z>1$的大质量SZ选星系团中搜寻弥漫射电辐射,发现8个射电晕(27%),并分析了射电功率与团块质量的标度关系,揭示了高红移下射电晕的探测率低于中等红移但仍高于理论预期。
我们展示了对一个均匀选择的30个红移$z>1$的最大质量Sunyaev-Zel'dovich选星系团样本中弥漫射电辐射的搜寻结果,首次提供了该红移以上团尺度弥漫射电辐射演化的统计约束。我们还分析了该高红移样本中射电功率($P_{1.4\,\mathrm{GHz}}$)与团块质量($M_{\rm 500c}$)之间的标度关系。已知射电晕主要存在于最大质量的星系团中,在那里主要并合产生的湍流能量可以重新加速相对论性电子并在兆秒差距尺度上放大磁场。深度的MeerKAT 1.28 GHz观测在8个星系团(27%)中揭示了弥漫射电晕,而其余21个(70%)未显示任何发射;另外1个星系团(3%)因数据质量差被排除在射电分析之外。该高红移样本中的射电晕探测率低于中等红移,但仍高于理论模型在$z \gtrsim 1$时普遍预测的$\lesssim 10\%$的出现率。探测到的射电晕围绕MMDCS样本的最佳拟合$P_{1.4\,\mathrm{GHz}}$-$M_{\rm 500c}^{\rm {Unc}}$关系散布,而非探测样本则占据射电功率-质量平面的下包络,与低红移观测到的趋势相似。未识别出团尺度的射电遗迹或迷你晕。我们的发现突显了MeerKAT探测最遥远星系团中非热过程的能力,以及需要更深的低频巡天来揭示微弱的弥漫发射并检验$P_{1.4\,\mathrm{GHz}}$-$M_{\rm 500}$关系在宇宙时间上的持续性。
We present the results of a search for diffuse radio emission in a uniformly selected sample of 30 of the most massive Sunyaev-Zel'dovich selected galaxy clusters at $z > 1$, providing the first statistical constraints on the evolution of cluster-scale diffuse emission beyond this redshift. We also analyse the scaling relations between radio power ($P_{1.4\,\mathrm{GHz}}$) and cluster mass ($M_{\rm 500c}$) in this high-redshift sample. It is well established that radio halos are primarily found in the most massive clusters, where turbulent energy from major mergers can re-accelerate relativistic electrons and amplify magnetic fields on megaparsec scales. Deep MeerKAT 1.28 GHz observations reveal diffuse radio halos in eight clusters (27$\%$), while the remaining 21 (70$\%$) show no emission; one additional cluster (3$\%$) was excluded from the radio analysis due to poor data quality. The halo detection rate in this high-redshift sample is lower than at intermediate redshift, but remains higher than the $\lesssim 10\%$ occurrence generally predicted by theoretical models at $z \gtrsim 1$. The detected radio halos scatter around the best-fitting $P_{1.4\,\mathrm{GHz}}$-$M_{\rm 500c}^{\rm {Unc}}$ relation derived for the MMDCS sample, whereas non-detections populate the lower envelope of the radio power-mass plane, similar to trends seen at lower redshift. No cluster-scale radio relics or mini-halos are identified. Our findings highlight MeerKAT's ability to probe non-thermal processes in the most distant clusters and the need for deeper, lower-frequency surveys to uncover faint diffuse emission and test the persistence of the $P_{1.4\,\mathrm{GHz}}$-$M_{\rm 500}$ relation across cosmic time.
第一光与再电离纪元模拟 (FLARES) XXII:再电离纪元的紫外-尘埃空间偏移
Paurush Punyasheel, Aswin P. Vijayan, William J. Roper, Thomas R. Greve, Hiddo Algera, Christopher C. Lovell, Steven Gillman, Bitten Gullberg, Shihong Liao, Robert M. Yates, Stephen M. Wilkins
AI总结 利用FLARES模拟和辐射传输代码,统计了高红移星系中紫外与远红外发射峰的空间偏移,发现约16%的星系存在≥2.5 kpc的偏移,且偏移与恒星质量、光度等无关,而与更蓝的紫外斜率、早期恒星形成历史及金属丰度相关。
最近的观测揭示了高红移星系中紫外(UV)和远红外(FIR)发射之间有趣的偏移。在本研究中,我们使用第一光与再电离纪元模拟(\textsc{Flares})计算了一个统计样本(6890个)中大质量(M$_{\\star}\\, \\gtrsim10^{9} \\,{\rm M_{\\odot}}$)高红移星系($z \\in [5,10]$)的紫外和远红外中心的空间偏移。这些星系经过\textsc{skirt}辐射传输代码的后处理,以获得完整的光谱能量分布和表面亮度分布。我们模拟了\textit{詹姆斯·韦伯空间望远镜(JWST)}近红外相机(NIRCam;静止帧1500 Å,分辨率约$0.031''$)和ALMA静止帧158 \um(角分辨率约$0.3''$)的观测,然后计算UV-FIR中心之间的距离,以分析驱动观测到的UV-FIR空间偏移的物理过程。我们发现约16.23%的星系在其UV和FIR发射峰值之间表现出$\\geq 2.5$ kpc的空间偏移。我们确定空间偏移与恒星质量、UV/FIR光度以及大小无关。偏移也与活动星系核反馈、大尺度环境或并合历史无关。具有显著偏移的星系优先表现出更蓝的紫外斜率($-2.5<β<-1.5$),这与最近的恒星形成和尘埃衰减的核心导致观测到的UV质心位移一致。它们显示出加速的恒星形成历史,比没有偏移的星系早约0.1 Gyr形成其$z=5$恒星质量的一半。这些星系比没有偏移的星系更早富集,并显示出增强的恒星金属丰度,表明在更高红移($z \\geq 6$)时向外生长的转变。
Recent observations have revealed intriguing offsets between the UV and FIR emission in high redshift galaxies. In this study, we use the First Light And Reionisation Epoch Simulations (\textsc{Flares}) to compute the spatial offset of ultraviolet (UV) and far-infrared (FIR) centres for a statistical sample (6890) of massive (M$_{\star}\, \gtrsim10^{9} \,{\rm M_{\odot}}$) high redshift galaxies ($z \in [5,10]$). The galaxies are post-processed with the \textsc{skirt} radiative transfer code, to obtain the full spectral energy distribution and surface brightness profile. We simulate \textit{James Webb Space Telescope (JWST)} Near Infrared Camera (NIRCam; rest-frame 1500 Å, $ \approx 0.031 ''$ resolution) and ALMA rest-frame 158 \um\ ($\approx$ $0.3''$ angular resolution) observations of the galaxies and then calculate the distance between the UV-FIR centres to analyse which physical processes drive the observed UV - FIR spatial offset. We find that $\sim16.23\%$ of galaxies exhibit spatial offsets of $\geq 2.5$ kpc between their UV and FIR emission peaks. We establish that the spatial offsets do not correlate with stellar mass, UV/FIR luminosity, and size. Offsets also do not correlate with AGN feedback or with large-scale environment or merger history. Galaxies with significant offsets preferentially have bluer UV slopes ($-2.5<β<-1.5$), consistent with recent star formation and dust-attenuated cores displacing the observed UV centroid. They show an accelerated star formation history, forming half their $z=5$ stellar mass $\sim$0.1 Gyr earlier than galaxies without offsets. These galaxies are enriched earlier than galaxies without an offset and show enhanced stellar metallicities, indicating a transition to an outward growth at higher redshifts ($z \geq 6$).
广义多级振幅阻尼通道及其热力学性能
Vito Vetrano, Vittorio Giovannetti, Vasco Cavina
AI总结 本文引入广义多级振幅阻尼(GMAD)通道来模拟与热环境耦合的qudit中的噪声和退相干效应,通过评估功泛函和ergotropic电容研究GMAD下能量资源的退化,揭示了ergotropic电容随环境温度非单调变化以及马尔可夫Mpemba效应等反直觉现象。
我们引入了一类新的量子通道,即广义多级振幅阻尼(GMAD)通道,用于模拟与热环境耦合的qudit中的噪声和退相干效应。通过评估功泛函和ergotropic电容,研究了GMAD下能量资源的退化,特别关注ergotropy的相干和非相干贡献,为此我们引入了新的量化指标。我们的分析揭示了如何在热环境中最优地制备qudit以从功提取的角度保留其价值,并揭示了几个反直觉的现象:GMAD通道的ergotropic电容随环境温度非单调变化;此外,迭代该映射可能导致不同温度下ergotropic泛函的交叉,表明存在马尔可夫Mpemba效应。
We introduce a new class of quantum channels, the Generalized Multilevel Amplitude Damping (GMAD) channels, to model noise and decoherence effects in a qudit coupled to a thermal environment. The degradation of energetic resources under GMADs is investigated by evaluating work functionals and ergotropic capacitances, with particular attention to the coherent and incoherent contributions to ergotropy, for which we introduce new quantifiers. Our analysis sheds light on how to optimally prepare a qudit in a thermal environment in order to preserve its value from the perspective of work extraction, and reveals several counterintuitive phenomena: the ergotropic capacitance of a GMAD channel is not monotonic in the temperature of the environment; moreover, iterating the map can lead to crossings between ergotropic functionals at different temperatures, indicating the presence of a Markovian Mpemba effect.
厚壁外尔半金属圆柱体中的自发持续电流和时间反演对称性破缺
J. C. Pérez-Pedraza, Juan A. Cañas, Daniel A. Bonilla, A. Martín-Ruiz
AI总结 通过低能有效哈密顿量解析求解厚壁外尔半金属圆柱体的本征值问题,发现外尔节点的空间分离作为内禀手征规范场,在零外磁通下自发破缺时间反演对称性,产生持续电流和电导通道展开。
我们理论研究了在外部轴向磁场作用下的厚壁外尔半金属(WSM)圆柱体中的阿哈罗诺夫-玻姆效应。通过采用低能有效哈密顿量,我们解析求解了无限长和有限长圆柱几何的本征值问题。在径向壁处应用无限质量边界条件,在圆柱帽处应用MIT袋边界条件,以分别正确考虑节点内约束和谷间散射。我们的数值结果表明,外尔节点的空间分离充当了内禀手征规范场。这个几何场内禀地破缺了时间反演(TR)对称性,即使在零外磁通下也解除了手征简并。这种对称性破缺表现为自发持续电流和电导通道的展开。此外,纵向约束诱导了传播方向依赖的能量分裂,改变了部分态密度并导致空间-手征电流不平衡。
We theoretically investigate the Aharonov-Bohm effect in a thick-walled Weyl semimetal (WSM) cylinder subject to an external axial magnetic field. By employing a low-energy effective Hamiltonian, we analytically solve the eigenvalue problem for both infinite and finite-length cylindrical geometries. We apply infinite-mass boundary conditions at the radial walls and MIT bag boundary conditions at the cylinder caps to properly account for intra-node confinement and inter-valley scattering, respectively. Our numerical results demonstrate that the spatial separation of the Weyl nodes acts as an internal chiral gauge field. This geometric field intrinsically breaks time-reversal (TR) symmetry, lifting the chiral degeneracy even at zero external flux. This symmetry breaking manifests as spontaneous persistent currents and the unfolding of conductance channels. Furthermore, longitudinal confinement induces propagation-direction-dependent energy splitting, altering the partial density of states and causing spatio-chiral current imbalances.
分钟级深度银心巡天:DREAMS首次数据发布
Hongjing Yang, Weicheng Zang, Francisco Valdes, Qiyue Qian, Yuchen Tang, Zhixing Li, Yuxin Shang, Shude Mao, Yaosong Yu, Guillermo Damke, Alfredo Zenteno, Steve Heathcote, Konstantina Boutsia, Andong Xu, Hao Ma, Jiyuan Zhang, Hongyu Li, Xikai Shan, Przemek Mróz, Xiurui Zhao, Andrew Gould, Jennifer C. Yee, Chung-Uk Lee, Matthew Penny, Sean Terry, Patrick Tamburo, Tim Cunningham, Quanzhi Ye, Eric W. Peng, Rachel Street, Katarzyna Kruszyńska, Etienne Bachelet, Yiannis Tsapras, Markus Hundertmark
AI总结 基于DECam的DREAMS巡天项目在银心5平方度区域进行三年分钟级测光观测,首次数据发布包含约5900万颗恒星的z波段和r波段光变曲线,用于探测低质量自由漂浮行星、恒星耀发和短时标变星。
DECam流浪地球与火星巡天(DREAMS)是NOIRLab的一个巡天项目,自2025年6月起在银心5平方度区域进行为期三年的巡天。其主要科学目标是通过微引力透镜探测低质量自由漂浮行星,同时其分钟级采样率还能探测和表征时标从分钟到小时的快速现象,如恒星耀发和脉动变星。本文介绍了2025年DREAMS观测数据的处理和校准,并发布了首次DREAMS数据(DR1)。DR1包含59,372,789颗恒星的1,856次z波段观测和325次r波段观测。DREAMS DR1星表包含的恒星数量至少是覆盖相同5平方度区域的其他星表的两倍。我们展示了已知蓝大振幅脉动变星和已知凌星系系统的DREAMS光变曲线,以展示巡天的能力。我们还对DR1样本中约0.4%的区域进行了短时标变星的试搜索,识别出一个新的短时标微引力透镜事件、两个恒星耀发和24个新的短时标变星。这表明DREAMS DR1可能包含数百个恒星耀发和数千个此前未知的短时标变星。
The DECam Rogue Earths and Mars Survey (DREAMS), a NOIRLab survey program, has been conducting a three-year survey covering a 5\,deg$^2$ area in the Galactic bulge since 2025 June. Its primary science goal is to detect low-mass free-floating planets through microlensing, while its minute-level cadence also enables the detection and characterization of rapid phenomena on timescales of minutes to hours such as stellar flares and pulsating stars. Here, we present the data reduction and calibration of the DREAMS observations obtained in 2025 and introduce the first DREAMS data release (DR1). DR1 includes 1,856 $z$-band observations and 325 $r$-band observations for 59,372,789 stars. The DREAMS DR1 catalog contains at least twice as many stars as any previous catalog covering the same 5\,deg$^2$ area. We present DREAMS light curves for a known blue large-amplitude pulsator and a known transiting system to demonstrate the survey's capabilities. We also perform a pilot search for short-duration variables over about 0.4% of the DR1 sample, identifying one new short microlensing event, two stellar flares, and 24 new short variables. This suggests that DREAMS DR1 may contain hundreds of stellar flares and thousands of previously unknown short variables.
NGC 4151外流首次近红外高分辨率阶梯光谱:覆盖索伦之眼的云团研究
Francesco Gabriele Saturni, Riccardo Middei, Hermine Landt, Valerio D'Elia, Fabio La Franca, Matteo Perri, Enrico Piconcelli
AI总结 利用IRTF/iSHELL和TNG/GIANO-B光谱仪对NGC 4151(“索伦之眼”)进行首次近红外高分辨率光谱观测,结合Swift-XRT数据,揭示He I吸收线变化与X射线电离连续谱变化相关,并限制外流物理参数。
我们展示了附近著名的赛弗特星系NGC 4151(“索伦之眼”)核区的首次高分辨率近红外光谱。过去对该源的研究揭示了一个与He I λ10,830 Å发射线相关的可变吸收特征,可能指示影响中央引擎的遮蔽事件。这里,我们利用IRTF/iSHELL和TNG/GIANO-B光谱仪以空前的光谱分辨率(λ/Δλ > 50,000)观测该特征,能够详细研究吸收槽的结构及其在约700天时间跨度内的变化。为了推断He I吸收变化与X射线电离连续谱变化之间的联系,我们还分析了同一时期由Swift-XRT仪器收集的公开数据,揭示了由于X射线通量变化导致的外流电离态变化的潜在驱动机制。我们还推导了外流物理参数——Ṁ_out ≲ 10^{-2} M_⊙ yr^{-1},r_out ~ 3 pc,v_max ~ 1000 km s^{-1}——这些参数与类似目标中发现的相当的电离风一致,其中外流不足以触发显著的AGN反馈(Ė_kin/L_bol ~ 0.001%)。这些发现指向一个场景:一个遮蔽NGC 4151直至星系尺度的尘埃和团块外流响应电离X射线通量的变化,类似于具有宽吸收线的类星体和具有多相外流的赛弗特星系(如NGC 5548)中发生的情况。
We present the first high-resolution near-infrared spectroscopy of the nucleus of the nearby, well-known Seyfert galaxy NGC 4151 (the "Eye of Sauron"). Past studies of this source have revealed that it exhibits a variable absorption feature associated with the He I $λ$10,830 AA emission line, potentially indicative of obscuration events affecting the central engine. Here, we take advantage of the IRTF/iSHELL and TNG/GIANO-B spectrographs to observe this feature with unprecedented spectral resolution ($λ/Δλ> 50,000$), being able to study in detail the structure of the absorption trough and its variations over a time span of $\sim$700 days. In order to infer a connection between the He I absorption variability and that of the X-ray ionising continuum, we also analyse the publicly available data collected by the Swift-XRT instrument over the same period of time, unveiling a potential driving mechanism in the changes of the outflow ionisation state due to the X-ray flux variations. We also derive outflow physical parameters - $\dot{M}_{\rm out} \lesssim 10^{-2}$ M$_\odot$ yr$^{-1}$, $r_{\rm out} \sim 3$ pc, $v_{\rm max} \sim 1000$ km s$^{-1}$ - that are in line with those of comparable ionised winds found in similar targets, where the outflow is not powerful enough to trigger a significant AGN feedback ($\dot{E}_{\rm kin}/L_{\rm bol} \sim 0.001$%). Such findings point at a scenario in which a dusty and clumpy outflow that obscures NGC 4151 up to galactic scales responds to changes in the ionising X-ray flux, similarly to what happens in quasars with broad absorption lines and Seyferts with multiphase outflows such as NGC 5548.
热木星的孤立并非高偏心率潮汐迁移所独有
Brandon Radzom, Songhu Wang, Bonan Pu, Hareesh Gautham Bhaskar, Malena Rice
AI总结 通过数值模拟表明,热木星在形成后与伴星的动力学演化自然导致其比暖木星更孤立,无需依赖高偏心率潮汐迁移。
传统上,观测到的热木星孤立性——即附近缺乏低质量行星伴星——被视为这些近距离气态巨行星经历高偏心率潮汐迁移的证据。这种孤独与暖木星常见的紧凑构型形成鲜明对比,暗示这两类短周期巨行星在动力学起源上存在奇特二分性。然而,在本研究中,我们对两类巨行星采用统一的宁静形成框架,即它们从原行星盘中作为紧凑多超级地球系统中的唯一木星行星出现。我们使用长期数值模拟表明,盘后动力学演化自然会导致热木星相对于暖木星在观测上更倾向于孤立。具体而言,它们的伴星实现了显著更大的周期比和相互倾角,使其更难被探测——尤其是通过凌星法。此外,我们发现这一范式与长周期热木星拥有共面轨道内部伴星的谜样群体一致。该模型的另一个预测——最好通过高精度多普勒巡天检验——是热木星存在一群近距离(周期<50天)但相互倾斜的外部伴星。
Conventionally, the observed isolation of hot Jupiters, marked by a paucity of nearby low-mass planetary companions, has been interpreted as evidence of high-eccentricity tidal migration for these close-in gas giants. This loneliness is in stark contrast with the compact configurations commonly observed for warm Jupiters, indicating a curious dichotomy in dynamical origins between these two classes of short-period giants. In this study, however, we adopt a unified quiescent framework for both giant populations wherein they emerge from the protoplanetary disk as the sole Jovian planet within a compact multi-super-Earth system. We use long-term numerical simulations to show that post-disk dynamical evolution will naturally result in an observed preferential isolation for hot Jupiters relative to warm Jupiters. Specifically, their companions achieve significantly larger period ratios and mutual inclinations, rendering them more difficult to detect - especially via the transit method. Additionally, we find that this paradigm is consistent with the enigmatic population of longer-period hot Jupiters hosting interior companions on coplanar orbits. Another prediction of this model, best tested through high-precision Doppler campaigns, is the existence of a population of close-in (P<50 days) but mutually inclined outer companions to hot Jupiters.
二维超对称杨-米尔斯理论中的非重整化定理与Wilson系数
Kabir Bajaj
AI总结 利用紫外规范理论中的非重整化论证,确定了矩阵弦理论中对称积轨形CFT的Dijkgraaf-Verlinde-Verlinde算符的Wilson系数,结果与矩阵弦理论猜想一致。
矩阵弦理论(arXiv:hep-th/9703030, arXiv:hep-th/9701025, arXiv:hep-th/9710009)是二维最大超对称$U(N)$杨-米尔斯理论与十维闵可夫斯基时空中的IIA型弦理论之间的猜想对偶。该规范理论的红外描述由对称积轨形$(\mathbb{R}^8)^N/S_N$ CFT主导。来自该红外不动点的最相关不可忽略形变是Dijkgraaf-Verlinde-Verlinde算符,它带有一个未知的Wilson系数。我们利用紫外规范理论中的非重整化论证确定了该系数。结果与矩阵弦理论猜想一致,并为$g_{\rm YM}$与弦耦合之间的关系提供了第一性原理检验。我们还评论了用类似方法确定其他Wilson系数的前景。
Matrix string theory (arXiv:hep-th/9703030, arXiv:hep-th/9701025, arXiv:hep-th/9710009) is a conjectured duality between two-dimensional maximally supersymmetric $U(N)$ Yang-Mills theory and type-IIA string theory in ten-dimensional Minkowski spacetime. The IR description of this gauge theory is governed by the symmetric product orbifold $(\mathbb{R}^8)^N/S_N$ CFT. The leading irrelevant deformation from this IR fixed point is the Dijkgraaf-Verlinde-Verlinde operator, which comes with an unknown Wilson coefficient. We determine this coefficient using non-renormalization arguments from the UV gauge theory. The result is consistent with the matrix string theory conjecture and gives a first-principles check of the relation between $g_{\rm YM}$ and the string coupling. We also comment on the prospects for fixing further Wilson coefficients using similar methods.
利用机器学习与引力波标准汽笛对宇宙学参数的高斯过程重建
Gourab Nandi, Anish Ghoshal, David F. Mota
AI总结 本文提出基于高斯过程回归的模型无关框架,通过分析LISA和爱因斯坦望远镜的模拟标准汽笛目录,重建共动距离及其导数,并利用导数敏感诊断量识别区分不同宇宙学模型的最佳红移窗口。
未来的引力波标准汽笛目录将探测传统电磁观测难以触及的红移范围内宇宙晚期膨胀历史。为确定这种背景距离信息区分可行宇宙学模型的有效性,我们引入了一个利用高斯过程回归(GPR)的模型无关重建框架。分析六个基准宇宙学背景——ΛCDM、CPL、CPL+Λ、相互作用暗物质、相互作用暗能量和轴子启发早期暗能量——下的模拟LISA和爱因斯坦望远镜(ET)目录。我们重建了共动距离及其导数。关键的是,我们传播了完整的GP协方差,包括导数交叉协方差,以稳健地评估哈勃参数$H(z)$及其他诊断量,如$q(z)$、$\mathcal{O}_{m}(z)$、$w_{ m total}(z)$和$\kappa(z)$。虽然我们的分析表明GW亮标准汽笛能忠实恢复基准膨胀历史,但应用逐点边缘Hellinger距离显示,仅背景测量无法提供模型间的决定性统计分离。相反,导数敏感诊断量精确指出了未来目录将最大化其区分能力的特定红移窗口(例如,ET的$z\simeq1.6-1.8$和LISA的$z\simeq2.6-2.9$)。随着机器学习方法在天体物理学和宇宙学中日益不可或缺,这一贝叶斯GPR流程提供了一种原则性的非参数方法,以精确识别最有价值的宇宙学信息所在之处。
Future gravitational wave (GW) standard siren catalogues will probe the late-time expansion history of the Universe across redshift ranges largely inaccessible to traditional electromagnetic observations. To determine how effectively this background distance information can distinguish between viable cosmological models, we introduce a model-independent reconstruction framework utilizing Gaussian Process Regression (GPR). Analyzing mock LISA and Einstein Telescope (ET) catalogues across six fiducial cosmological backgrounds-$Λ$CDM, CPL, CPL+$Λ$, interacting dark matter, interacting dark energy and axion inspired early dark energy. We reconstruct the comoving distance and its derivatives. Crucially, we propagated the full GP covariance, including derivative cross-covariances, to robustly evaluate the Hubble parameter $H(z)$ and other diagnostics such as $q(z)$, $\mathcal{O}_{m}(z)$ $w_{\rm total}(z)$ and $κ(z)$. While our analysis demonstrates that GW bright standard sirens faithfully recover fiducial expansion histories, applying pointwise marginal Hellinger distance reveals that background measurements alone do not provide decisive statistical separation among models. Instead, derivative sensitive diagnostics pinpoint specific redshift windows (e.g., $z\simeq1.6-1.8$ for ET and $z\simeq2.6-2.9$ for LISA) where future catalogues will maximize their discriminatory power. As machine learning methodologies become increasingly integral to astrophysics and cosmology, this Bayesian GPR pipeline offers a principled, nonparametric approach to precisely identifying where the most valuable cosmological information lies.
低维超流体的量子电阻悖论
Simon Wili, Meng-Zi Huang, Tommaso Bonaccorsi, Michael Mühlematter, Mohsen Talebi, Yaakov Yudkin, Alex Gómez-Salvador, Filip Marijanovic, Eugene Demler, Tilman Esslinger
AI总结 通过无缺陷均匀费米气体在数字可编程输运几何中的实验,发现从一维到二维的交叉中电阻达到最小值,揭示了相滑移和涡旋两种耗散机制之间的转变。
标准导体中的电阻随横截面积增大而减小。然而,在低维超导体和超流体中,剩余电阻源于序参量的拓扑涨落,表现为一维系统中的相滑移和二维系统中的涡旋。当几何结构在这些区域之间插值时,电阻和耗散如何演变仍是一个悬而未决的问题。这种演变在固态实验中因无序、杂质和几何缺陷而被掩盖,并且由于竞争性的耗散过程和显著的有限尺寸效应而带来理论挑战。在这里,我们使用数字可编程输运几何中的无缺陷均匀费米气体来隔离几何效应对超流体耗散的影响,并发现一个悖论:在一维到二维的交叉中,电阻达到最小值。在那里,加宽通道会增加其电阻。更窄的准一维通道表现出由Langer-Ambegaokar-McCumber-Halperin相滑移理论描述的耗散。在这个区域,改变通道宽度使得激活因子的指数标度在超过十个数量级上得到验证。更宽的准二维通道表现出与有限尺寸涡旋模型一致的耗散。维度交叉中的最小耗散反映了主导耗散机制的转变,其中相滑移和涡旋同时被抑制。我们的测量为最小化超导器件中的耗散提供了一条途径,并为旨在描述维度交叉的理论工作提供了基准。
Resistance in standard conductors decreases with increasing cross-section. Yet, in low-dimensional superconductors and superfluids residual resistance arises from topological fluctuations of the order parameter manifesting as phase slips in one-dimensional (1D) and vortices in two-dimensional (2D) systems. How resistance and dissipation evolve as geometry interpolates between these regimes remains an open question. This evolution is masked in solid-state experiments by disorder, impurities, and geometric imperfections, and poses theoretical challenges due to competing dissipative processes and pronounced finite-size effects. Here, we use a defect-free unitary Fermi gas in a digitally programmable transport geometry to isolate geometric effects on superfluid dissipation and discover a paradox: in the crossover from 1D to 2D, the resistance reaches a minimum. There, widening a channel increases its resistance. Narrower, quasi-1D channels show dissipation described by Langer-Ambegaokar-McCumber-Halperin theory of phase slips. In this regime, varying the channel width yields the predicted exponential scaling of the activation factor over more than ten orders of magnitude. Wider, quasi-2D channels show dissipation consistent with a finite-size vortex model. The minimal dissipation in the dimensional crossover reflects a transition in the dominant dissipative mechanism, with both phase slips and vortices simultaneously suppressed. Our measurements suggest a route to minimizing dissipation in superconducting devices and provide a benchmark for theoretical efforts aimed at describing the dimensional crossover.
云对亚海王星大气-地幔界面的影响
Sagnick Mukherjee, Matthew C. Nixon, Luis Welbanks, James Mang, Nicholas F. Wogan, Natasha E. Batalha, Michael R. Line
AI总结 使用PICASO 1D气候模型耦合内部结构和岩浆-大气化学框架,量化云如何改变亚海王星的大气和内部结构,发现云会导致深层加热和浅层冷却,并显著改变界面组成。
亚海王星是我们银河系中最常见的近距离行星类型之一,但其整体组成仍然很大程度上不确定;富含H的包层覆盖岩石核心、富含挥发物的行星和富含碳的内部都是这一群体成员的可行配置。大气表征已被提议作为区分这些情景的手段,但越来越多的证据表明,亚海王星可能拥有熔融的大气-地幔界面,这可能会改变其大气成分。我们使用PICASO 1D气候模型,结合内部结构和岩浆-大气化学框架,量化云如何改变亚海王星的大气和内部结构。对于像TOI-270 d这样的温带亚海王星,我们发现云可以导致深层(约10^4 bar)加热≥1000 K,以及在浅层压力(约1 bar)下冷却约600 K。这种加热对云沉降效率非常敏感,对金属丰度敏感程度较低。我们样本中的大多数亚海王星应该具有熔融的大气-地幔界面,除了TOI-1231 b和GJ 1214 b。对于这两颗行星,多云模型具有熔融界面,而晴空模型可能允许固体边界。对于我们样本中的大多数亚海王星,云可以使大气-地幔界面加热约1400-2600 K的温度差。这种云驱动的加热可以显著改变界面的组成,在TOI-270 d的多云和晴空模型中,O₂、SiH₄和SiO的丰度增加了≥36%。我们讨论了我们的结果对这一群体的热演化和内部热通量测量的影响。
Sub-Neptunes are among the most common type of close-in planets found in our galaxy, yet their bulk composition remains largely uncertain; H-rich envelopes overlaying rocky cores, volatile-rich planets, and carbon-rich interiors all remain viable configurations for members of this population. Atmospheric characterization has been proposed as a means of distinguishing between these scenarios, but growing evidence suggests that sub-Neptunes may host molten atmosphere-mantle interfaces which could alter the composition of their atmosphere. We use the PICASO 1D climate model, coupled to interior-structure and magma-atmosphere chemistry frameworks to quantify how clouds alter the atmospheric and interior structure of sub-Neptunes. For temperate sub-Neptunes like TOI-270 d, we find that clouds can lead to $\ge{1000}$ K heating at depth (${\sim}10^{4}$ bar) and $\sim{600}$ K cooling at shallow pressures ($\sim$1 bar). This heating is very sensitive to the cloud sedimentation efficiency and, to a lesser extent, to metallicity. Most sub-Neptunes in our sample should have a molten atmosphere-mantle interface, except TOI-1231 b and GJ 1214 b. For these two planets, cloudy models have a molten interface whereas clear models can allow a solid boundary. Clouds can heat the atmosphere-mantle interfaces by a temperature difference between $\sim{1400}-2600$ K for most sub-Neptunes in our sample. Such cloud-driven heating can substantially change the composition of the interface with abundances of O$_2$, SiH$_4$, and SiO showing a $\ge{36}$\% increase between cloudy and clear models of TOI-270 d. We discuss the implications of our results for the thermal evolution and measurements of intrinsic heat flux for this population.
受监测自旋链中无后选择的弹道-扩散转变
K. G. S. H. Gunawardana, Ali G. Moghaddam, Teemu Ojanen
AI总结 研究周期性监测下自旋1/2 XXZ链的自旋与纠缠动力学,发现两种测量诱导的相变:稳态纠缠相变和瞬态动力学中的弹道-扩散转变,后者无需后选择即可观测,是实验可及的多体Zeno效应表现。
我们研究了周期性监测下自旋1/2 XXZ链的自旋与纠缠动力学,并表明该系统表现出两种测量诱导的相变:类似于受监测量子电路中的稳态纠缠相变,以及瞬态动力学中的弹道到扩散转变。具体来说,我们发现低监测率下,包含畴壁$|\uparrow\uparrow\uparrow\ldots \downarrow\downarrow\downarrow\ldots\rangle$的初始构型呈弹道扩散,而高监测率下,畴熔化是扩散性的。大量数值模拟及理论论证表明,弹道-扩散转变与纠缠相变密切相关。与需要指数复杂后选择的纠缠相变不同,弹道-扩散转变无需后选择即可观测,构成了多体Zeno效应的实验可及表现。
We study spin and entanglement dynamics in spin-1/2 XXZ chains under periodic monitoring and show that this system exhibits two measurement-induced phase transitions: a steady-state entanglement phase transition similar to those in monitored quantum circuits and a ballistic-to-diffusive transition in transient dynamics. Specifically, we discover that at low monitoring rate, an initial configuration containing a domain wall $|\uparrow\uparrow\uparrow\ldots \downarrow\downarrow\downarrow\ldots\rangle$ spreads ballistically while, at large monitoring rates, the domain melting is diffusive. Extensive numerical simulations, supported by theoretical arguments, indicate that the ballistic-diffusive transition is intimately interlinked with the entanglement phase transition. In contrast to the entanglement phase transitions, which require exponentially complex postselection, the ballistic-diffusive transition can be observed without postselection and constitutes an experimentally accessible manifestation of the many-body Zeno effect.
实时核-电子轨道含时密度泛函理论中的约束行进质子基组
Nicholas J. Boyer, Sharon Hammes-Schiffer
AI总结 提出约束行进质子基组方法,在实时核-电子轨道含时密度泛函理论中实现质子动力学模拟,准确计算振动频率并模拟激发态分子内质子转移。
核量子效应和非玻恩-奥本海默效应在许多化学和生物过程中起着至关重要的作用,促使将这些效应纳入动力学模拟。在实时核-电子轨道含时密度泛函理论(RT-NEO-TDDFT)中,电子和核密度根据含时薛定谔方程在时间上进行数值传播。在该框架下,特定质子与电子在同一水平上被量子力学处理。经典核可以通过埃伦费斯特动力学在瞬时NEO振动表面上传播。行进质子基组(TPB)可用于描述移动质子的动力学,并结合每个量子质子的高斯型质子基组和电子基组。本文提出了一种约束行进质子基组(c-TPB)方法,确保在动力学过程中每个质子基函数中心与相应的质子位置期望值一致。该方法能够产生准确的核-电子量子动力学,并严格守恒能量。我们通过计算分子振动频率以及模拟邻羟基苯甲醛和[2,2'-联吡啶]-3,3'-二醇分子中的激发态分子内质子转移和双质子转移,展示了该方法的准确性和稳定性。这些应用表明,c-TPB方法提供了准确的动力学,守恒能量,并且计算效率高。
Nuclear quantum effects and non-Born--Oppenheimer effects play a vital role in many chemical and biological processes, motivating the incorporation of such effects into dynamical simulations. In real-time nuclear--electronic orbital time-dependent density functional theory (RT-NEO-TDDFT), the electronic and nuclear densities are propagated numerically in time according to the time-dependent Schrödinger equation. In this framework, specified protons are treated quantum mechanically on the same level as the electrons. The classical nuclei can be propagated on the instantaneous NEO vibronic surface using Ehrenfest dynamics. A traveling proton basis (TPB) can be used to describe the dynamics of moving protons in conjunction with Gaussian-type protonic and electronic basis sets for each quantum proton. Herein, we present a constrained TPB (c-TPB) approach that ensures each protonic basis function center coincides with the corresponding proton position expectation value during the dynamics. This approach produces accurate nuclear--electronic quantum dynamics and rigorously conserves energy. We demonstrate the accuracy and stability of this approach for computing molecular vibrational frequencies as well as simulating excited-state intramolecular proton transfer and double proton transfer in the o-hydroxybenzaldehyde and [2,2$'$-bipyridyl]-3,3$'$-diol molecules. These applications show that the c-TPB method provides accurate dynamics, conserves energy, and is computationally efficient.
忆阻器迟滞回线的相-拓扑分类:基于自交叉点
Ovidiu-Zeno Lipan, Eric Neuhaus, Rafael Schio Wengenroth Silva, Soumen Pradhan, Fabian Hartmann, Leonardo K. Castelano, Ana Luiza Costa Silva, Sven Höfling, Victor Lopez-Richard
AI总结 本文引入拓扑与代数框架,将忆阻器迟滞回线的横向自交点数作为鲁棒的整数值不变量,利用微分拓扑、奇点理论和尖点突变,通过判别式和结式对六维参数空间进行分层,实现所有多叶迟滞行为的完整分类。
忆阻器件革新了非易失性存储和神经形态计算,但其迟滞回线的几何结构——特别是多个自交叉点的出现和鲁棒性——仍知之甚少。本文引入一个拓扑和代数框架,将忆阻器迟滞回线的横向自交点数视为一个鲁棒的整数值不变量。借助微分拓扑、奇点理论和尖点突变,我们使用判别式和结式对六维参数空间进行分层。该方法将参数空间划分为结构稳定的区域,这些区域由可显式计算的突变面分隔。我们证明了交叉数在连续变形下严格不变,仅在自切或尖点奇点处发生变化,从而提供了所有多叶迟滞行为的完整分类。这些见解将器件物理学与现代奇点理论联系起来,并为在下一代电子学和类脑硬件中利用高阶记忆效应提供了清晰的路线图。
Memristive devices have revolutionized non-volatile memory and neuromorphic computing, yet the geometry of their hysteresis loops -- in particular, the occurrence and robustness of multiple self-crossings -- remains poorly understood. Here we introduce a topological and algebraic framework that treats the number of transverse self-intersections of a memristor hysteresis loop as a robust integer-valued invariant. Drawing on differential topology, singularity theory, and cusp catastrophe, we employ discriminants and resultants to stratify the six-dimensional parameter space. This approach partitions the parameter space into structurally stable regions separated by explicitly computable catastrophe surfaces. We demonstrate that the crossing number remains strictly invariant under continuous deformations and changes only at self-tangencies or cusp singularities, thereby providing a complete classification of all multi-lobed hysteresis behaviors. These insights bridge device physics with modern singularity theory and suggest a clear roadmap for exploiting higher-order memory effects in next-generation electronics and brain-inspired hardware.
二维Zakharov-Kuznetsov方程的谱性质
Justin Holmer, Svetlana Roudenko
AI总结 本文研究二维Zakharov-Kuznetsov方程维里算子的谱性质,通过解析分析将问题简化为数值验证内积符号和特征值,为孤立波的爆破或渐近稳定性提供关键要素。
我们讨论了二维Zakharov-Kuznetsov (ZK) 方程维里算子的谱性质。这是建立高维问题中孤立波爆破或渐近稳定性的关键要素。该模型在三维情形下最初由Zakharov和Kuznetsov在等离子体物理中引入,也是著名的Korteweg-de Vries (KdV) 方程的高维推广。ZK方程中孤立波的稳定性或修正ZK(或KdV型)方程中的稳定爆破是一个重要的物理问题,其中维里算子及其谱性质是分析的基本要素。在本文中,我们解析地研究该问题,并将其简化为仅需数值验证某些内积的符号和某些特征值。
We discuss a spectral property for the virial operator of the 2D Zakharov-Kuznetsov (ZK) equation. This is a crucial ingredient to establish blow-up or asymptotic stability of solitary waves in higher-dimensional problems. This model in 3D setting was originally introduced by Zakharov and Kuznetsov in plasma physics, and is also a higher-dimensional generalization of the well-known Korteweg-de Vries (KdV) equation. The problem of stability of solitary waves in ZK equation or stable blow-up in modified ZK (or KdV-type) equation is an important physical question, for which virial operators and their spectral properties are the essential elements of the analysis. In this paper we investigate this problem analytically and reduce it to verifying numerically only some signs of inner products and certain eigenvalues.
具有递归相关雪崩的硅光电倍增管的闭式解析电荷响应模型
Yiqi Liu, Xuewei Liu, Benda Xu
AI总结 针对硅光电倍增管(SiPM)的完整电荷响应谱,提出一种无需截断和数值卷积的闭式解析模型,通过特征函数框架统一处理基底噪声、单电子响应、光学串扰和后脉冲效应,并推导出用于事件级能量重建的显式电荷-时间似然函数。
硅光电倍增管(SiPM)已成为下一代中微子实验的首选光电探测器,然而,对于其完整的电荷响应谱,目前尚未建立统一的、无截断和数值卷积的闭式解析表达式,该表达式必须同时捕捉传统光电倍增管(PMT)中不存在的相关串扰和后脉冲效应。我们在特征函数框架内提出了一种统一的SiPM电荷响应闭式模型,将基底噪声、单电子响应(SER)电荷、内部光学串扰和后脉冲同等对待。特征函数表示将完整的电荷谱分解为三个独立的物理分量:基底、单电子响应(SER)和雪崩计数统计。瞬时光学串扰被建模为具有泊松后代的Galton-Watson分支过程;基于Vinogradov识别的广义泊松计数统计,我们通过Lagrange-Bürmann反演推导出总后代概率生成函数(PGF)的Lambert $W$闭式,为高效的事件级重建提供了解析工具。后脉冲被建模为每次雪崩的几何链,推导为最大熵泊松-伽马混合:指数先验(对于具有固定均值的正连续产额的最大熵)在泊松计数上边缘化后,得到每次雪崩的几何分布,其$N$次雪崩总和为负二项分布。这自然包含了泊松后脉冲极限和递归后脉冲链,同时保持了解析闭式性。所得八参数表达式进一步用于推导显式的每通道电荷-时间似然函数,用于事件级能量重建,而无需在推理时进行数值卷积。
Silicon photomultipliers (SiPMs) have become the preferred photodetectors in next-generation neutrino experiments, yet no unified closed-form analytical expression free of truncation and numerical convolution has been established for their full charge response spectrum, which must simultaneously capture correlated cross-talk and afterpulsing effects absent in conventional photomultiplier tubes (PMTs). We present a unified closed-form model for the SiPM charge response within the characteristic-function framework, treating pedestal noise, single-electron-response (SER) charge, internal optical cross-talk, and afterpulsing on equal footing. The characteristic-function representation factorises the full charge spectrum into three independent physical components: pedestal, single-electron response (SER), and avalanche count statistics. Prompt internal optical cross-talk is modelled as a Galton-Watson branching process with Poisson offspring; building on the Generalised Poisson count statistics identified by Vinogradov, we derive a Lambert $W$ closed form for the total-progeny PGF via Lagrange-Bürmann inversion, providing the analytical handle needed for efficient event-level reconstruction. Afterpulsing is modelled as a per-avalanche geometric chain, derived as the maximum-entropy Poisson-Gamma mixture: the exponential prior-maximum-entropy for a positive continuous yield with fixed mean-marginalised over a Poisson count yields the geometric per-avalanche distribution, whose $N$-avalanche total is Negative Binomial. This naturally encompasses the Poisson afterpulsing limit and recursive afterpulse chains while preserving analytical closure. The resulting eight-parameter expression is further applied to derive an explicit per-channel charge-time likelihood for event-level energy reconstruction without numerical convolution at inference time.
超大质量黑洞:强磁化和弱磁化错位吸积盘的建模
Joshua Samuel Stanway, Cora Prather, Derek Ward-Thompson, Timothy J. Walton, Brett Patterson, Hyerin Cho
AI总结 通过GRMHD模拟研究不同初始错位角和磁场配置下的吸积盘,发现磁抑制盘(MAD)状态可使盘在极端错位下与黑洞对齐,而弱磁场盘保持错位且最大倾斜角约50°。
在本文中,我们对旋转超大质量黑洞周围的错位吸积盘进行了数值研究。我们使用广义相对论磁流体动力学(GRMHD)代码KHARMA,进行了一项参数调查,涵盖了初始盘错位角($\mathcal{T}_\mathrm{init}=15^\circ, 45^\circ, 75^\circ$)的范围,并采用了磁抑制盘(MAD)或标准正常演化(SANE)磁场配置。我们发现,MAD状态下的模型可以与黑洞对齐至约$10 \, r_g$,即使在极端错位模型($\mathcal{T}_\mathrm{init}=75^\circ$)中也是如此,这是以前未曾见过的。没有动态重要磁场的模型在黑洞附近仍然保持错位,最大盘倾斜出现在约$10 \, r_g$处,峰值距黑洞的径向距离随盘错位增加而增加。然而,最大盘倾斜与初始盘错位并非线性关系,且似乎有一个最大值约$50^\circ$。我们还展示了KHARMA产生的错位盘模拟结果与其它GRMHD代码在多种问题下是一致的。
In this paper, we carry out a numerical study of misaligned accretion disks around spinning supermassive black holes. Here, we conduct a parameter survey covering a range of initial disk misalignment angles ($\mathcal{T}_\mathrm{init}=15^\circ, 45^\circ, 75^\circ$) with either the Magnetically Arrested Disk (MAD) or Standard And Normal Evolution (SANE) magnetic field configurations, using the general-relativistic magnetohydrodynamic (GRMHD) code KHARMA. We find that models in the MAD state can align with the black hole up to $\sim10 \, r_g$, even in extremely misaligned models ($\mathcal{T}_\mathrm{init}=75^\circ$), which has not been seen before. Models without a dynamically important magnetic field remain misaligned up to the black hole, with a maximum disk tilt at $\sim10 \, r_g$, the peak's radial distance from the black hole increases with increasing disk misalignment. However, the maximum disk tilt does not have a linear relationship with the initial disk misalignment, and appears to have a maximum value of $\sim50^\circ$. We also show misaligned disk simulations produced in KHARMA are consistent with other GRMHD codes, for a variety of problems.
量子电机械系统中的自主振荡:张量网络处理
Mahasweta Pandit, Sheikh Parvez Mandal, Mark T. Mitchison, Javier Prior
AI总结 本文提出张量网络框架,结合振动模式的二进制表示与介观储层嵌入,无需实时传播即可描述纳米电机械系统中由输运诱导的自持振荡,并揭示了强电机械反作用、非绝热振荡器动力学和能量相关电子隧穿过程竞争下的振荡行为。
电机械系统中输运诱导的自持振荡将静态电化学偏压转化为稳健的自主振荡运动,无需任何外部周期驱动。然而,在同时具有大玻色子希尔伯特空间、强相互作用和结构化费米子引线的纳米尺度电机械器件中,对这种自振荡的精确描述仍然具有挑战性。我们制定了一个张量网络框架,该框架将振动模式的二进制表示与介观储层嵌入相结合,无需显式实时传播即可控制地访问自振荡稳态和相关的输运可观测量。我们展示了在广泛的操作条件下机械自振荡的出现,其中强电机械反作用、非绝热振荡器动力学和能量相关的电子隧穿过程相互竞争。此外,我们观察到,对于慢速和快速振动的机械模式,在电机械耦合强度扫描过程中,自振荡窗口内振动占据数涨落的抑制之前会出现占据数涨落的峰值。总的来说,我们探索了内在系统特性和环境参数如何在广泛的操作条件下支配这种自主振荡。我们框架的通用性将使该方法能够直接应用于更复杂或实验相关的场景。
Transport-induced self-sustained oscillations in electromechanical systems convert a static electrochemical bias into robust, autonomous oscillatory motion in the absence of any external periodic drive. However, an exact description of such self-oscillations remains challenging in nanoscale electromechanical devices featuring a simultaneously large bosonic Hilbert space, strong interactions, and structured fermionic leads. We formulate a tensor-network framework that combines a binary representation of the vibrational mode with mesoscopic reservoir embeddings that enable controlled access to the self-oscillatory steady states and relevant transport observables without explicit real-time propagation. We demonstrate the emergence of mechanical self-oscillations across a broad set of operating conditions, in which strong electromechanical backaction, nonadiabatic oscillator dynamics, and energy-dependent electronic tunneling processes compete. Furthermore, we observe that for both slow and fast vibrating mechanical modes, suppressed vibrational occupation fluctuations in the self-oscillation window along the electromechanical coupling strength sweep is preceded by a peak in the occupation fluctuations. Collectively, we explore how both intrinsic system properties and environmental parameters govern such autonomous oscillations over a broad range of operating conditions. The generality of our framework will enable the method to be employed straightforwardly to more complicated or experimentally relevant scenarios.
微观结构感知的深度学习桥接原子尺度与宏观尺度实现冲击到爆轰预测
Simon Gonzalez-Zapata, Aidan Pantoya, Chunyu Li, Marisol Koslowski, Alejandro Strachan
AI总结 针对含能材料中冲击到爆轰转变的多尺度耦合难题,提出MISTnetX卷积深度神经网络,直接桥接大规模分子动力学模拟与连续介质有限元模型,实现无参数预测完整爆轰转变过程。
含能材料中的冲击到爆轰转变由跨越埃到毫米、飞秒到微秒的耦合过程控制,传统多尺度模型因缺乏尺度分离而失效。我们通过使用卷积深度神经网络MISTnetX直接桥接大规模分子动力学(MD)模拟与连续介质有限元(FE)模型来应对这一重大挑战。MISTnetX在通过复杂微观结构传播的冲击MD模拟上训练,捕捉冲击-微观结构相互作用、热点形成以及向爆燃的转变,为力学、冲击、热输运和化学的FE模拟提供关键的子网格信息。应用于合成但真实的纳米结构塑料粘结RDX复合材料,MISTnetX实现了无参数预测完整的爆轰转变过程。
The shock-to-detonation transition in energetic materials is governed by coupled processes spanning Angstroms to millimeters and femtoseconds to microseconds, where traditional multiscale models fail due to the lack of scale separation. We address this grand challenge by directly bridging large-scale molecular dynamics (MD) simulations with continuum finite-element (FE) models using MISTnetX, a convolutional deep neural network. Trained on MD simulations of shock propagation through complex microstructures, MISTnetX captures shock-microstructure interactions, hotspot formation, and the transition to deflagration, supplying critical sub-grid information to FE simulations of mechanics, shocks, thermal transport, and chemistry. Applied to a synthetic but realistic nanostructured plastic-bonded RDX composite, MISTnetX enables parameter-free prediction of the full run-to-detonation transition.
在 $f(R, L_{m})$ 引力中通过参数化哈勃函数约束重建宇宙膨胀
Khomesh R. Patle, G. P. Singh
AI总结 采用 $f(R, L_{m}) = \frac{R}{2} + L_{m}^\lambda$ 函数形式,引入三种基于红移相关哈勃参数 $H(z)$ 的宇宙学模型,通过贝叶斯方法约束模型参数,研究宇宙膨胀历史及能量条件、态诊断等,并验证热力学可行性。
我们在 $f(R, L_{m})$ 引力框架内,通过采用一个动机良好的函数形式 $f(R, L_{m}) = \frac{R}{2} + L_{m}^\lambda$ 来探测宇宙膨胀情景。具体来说,我们引入了三种新颖的宇宙学模型,这些模型用红移相关的哈勃参数 $H(z)$ 表述,为潜在的宇宙动力学提供了更深入的见解。这些模型进一步用于研究宇宙的膨胀历史以及几个宇宙学参数的演化。通过使用基于 $\chi^{2}$ 最小化技术的贝叶斯方法,针对宇宙计时器(CC)和联合(CC+Pantheon)数据集确定了模型参数的中值。对减速参数、能量密度、压强和状态方程参数进行了全面研究,以理解宇宙的演化。此外,还彻底检查了能量条件的有效性和态诊断的行为。最后,通过温度和熵密度的演化确认了模型的热力学可行性,并且估算的宇宙年龄进一步证明了与晚期天文观测的良好一致性。
We probe the cosmic expansion scenario within the framework of $f(R, L_{m})$ gravity by employing a well-motivated functional form of $f(R, L_{m}) = \frac{R}{2} + L_{m}^λ$. Specifically, we introduce three novel cosmological models formulated in terms of the redshift-dependent Hubble parameter $H(z)$, offering deeper insights into the underlying cosmic dynamics. The models are further utilized to investigate the expansion history of the universe and the evolution of several cosmological parameters. By using the Bayesian methods based on the $χ^{2}$-minimization technique, the median values of the model parameters are determined for the cosmic chronometer (CC) and joint (CC+Pantheon) datasets. A comprehensive study of the deceleration parameter, energy density, pressure and the equation of state parameter is carried out to understand the universe's evolution. Additionally, the validity of the energy conditions and the behavior of the statefinder diagnostic are thoroughly examined. Finally, the thermodynamic viability of the models is confirmed through the evolution of temperature and entropy density, and the estimated age of the universe further exemplifies good agreement with late-time astronomical observations.
狄拉克朗道极化子中超辐射相变的缺失
Elsa Jöchl, Felix Helmrich, Frieder Lindel, Lucy Hale, Lorenzo Graziotto, Mona Jarrahi, Tobia F. Nova, Jérôme Faist, Giacomo Scalari
AI总结 通过太赫兹光谱测量,发现石墨烯朗道极化子在超强耦合下未出现超辐射相变,排除了No-Go定理规避的可能性。
光子凝聚成宏观占据的基态,即超辐射相变(SRPT),是腔量子电动力学(cQED)最引人注目的预测之一,但在平衡态中五十多年来一直未能实验实现。这种相变是否能在光-物质耦合系统中存在仍存在争议,一个广泛建立的No-Go定理在多个模型中排除了它的可能性。石墨烯回旋跃迁与太赫兹(THz)腔的超强耦合一直是这一争论的核心。在领头阶,电子的线性狄拉克色散不产生执行该定理的抗磁$\\vec{A}^2$项,使石墨烯成为规避No-Go定理的最清洁候选者。\n在这里,我们首次展示了封装单层石墨烯薄片与单个互补开口谐振环超强耦合的太赫兹光谱测量。通过调节载流子密度,我们将系统从弱耦合扫入超强耦合区域,达到归一化耦合强度$Ω_\\text{R}/ω_\\text{cav} \\\approx 0.4$。这已进入二阶SRPT会通过下极化子分支软化而显现的范围,但我们并未观察到。完整的极化子色散反而由基于第一性原理的Hopfield哈密顿量定量再现,该哈密顿量使用近场模型考虑了腔的亚波长特性。\n我们的结果为二维狄拉克系统中腔驱动相变的预测建立了实验基准,并排除了在当前可达到的最强耦合下石墨烯朗道极化子中规避No-Go定理的SRPT,这对固体cQED中真空诱导有序的提议有直接影响。
The condensation of photons into a macroscopically populated ground state, a superradiant phase transition (SRPT), is one of the most striking predictions of cavity quantum electrodynamics (cQED), yet has resisted experimental realization in equilibrium for over fifty years. Whether such a transition can survive at all in light-matter coupled systems is still debated, with a widely established \textit{No-Go} theorem ruling it out across several models. Graphene cyclotron transitions ultrastrongly coupled to terahertz (THz) cavities have been at the heart of this debate. At leading order, the linear Dirac dispersion of electrons does not generate the diamagnetic $\vec{A}^2$ term that enforces the theorem, making graphene the cleanest candidate for a No-Go-evading phase transition. Here, we present the first THz spectroscopic measurements of an encapsulated monolayer graphene flake ultrastrongly coupled to a single complementary split-ring resonator. By tuning the carrier density we sweep the system from weak coupling into the ultrastrong regime, reaching a normalized coupling $Ω_\text{R}/ω_\text{cav} \approx 0.4$. This is well into the range where a second order SRPT would manifest by a softening of the lower polariton branch, which we do not observe. The full polariton dispersion is instead quantitatively reproduced by a Hopfield Hamiltonian derived from first principles using a near-field model that accounts for the sub-wavelength character of the cavity. Our results establish an experimental baseline for predictions of cavity-driven phase transitions in two-dimensional Dirac systems, and rule out a No-Go-evading SRPT in graphene Landau polaritons up to the strongest couplings accessible today, with direct implications for proposals invoking vacuum-induced order in solid-state cQED.
具有Wronskian的有限维多项式代数在$\mathbb{R}^d$上作为$N$元李括号的显式类:超越$\mathfrak{sl}(2)$
Markuss G. Ķēniņš, Arthemy V. Kiselev
AI总结 本文通过广义完全Wronskian作为$N$元括号,显式构造了$\mathbb{R}^d$上所有有限维多项式强同伦李代数,并得到了结构常数中广义Vandermonde行列式的分解公式。
李代数$\mathfrak{sl}(2)$可以通过$\mathbb{R}^1\ni x$上具有多项式系数$1$, $-2x$, $-x^2$的向量场实现;它们的Wronskian行列式产生李括号。类似地,单项式$1$, $\ldots$, $x^k/k!$, $\ldots$, $x^N/N!$张成有限维强同伦(SH)李代数,其中Wronskian $\mathbf{1} \wedge \partial_x \wedge \ldots \wedge \partial_x^{N-1}$作为$N$元括号。在维数$d=2$且$\mathbb{R}^2\ni(x,y)$的情况下,对于微分阶$k=1$的广义完全Wronskian $W^{d=2}_{k=1}=\mathbf{1}\wedge \partial_x \wedge \partial_y$作为三元括号,有限维多项式SH李代数由$\langle 1$, $x$, $y$, $p\rangle$张成,其中$p\in\{x^2$, $xy$, $y^2\}$。我们显式描述了所有有限维多项式SH李代数$\Bbbk_k[{\boldsymbol{x}}]\subseteq \mathcal{A} \subseteq \Bbbk[x^1,\ldots,x^d]$($\Bbbk=\mathbb{R}$或$\mathbb{C}$),其中阶为$k$的完全广义Wronskian $W^{d\geqslant 1}_{k\geqslant 1}$作为$N$元括号:$N=\binom{d+k}{d}$。我们得到了多项式代数$\mathcal{A}$的结构常数中出现的广义Vandermonde行列式的分解公式。
Lie algebra $\mathfrak{sl}(2)$ can be realised by vector fields on $\mathbb{R}^1\ni x$ with polynomial coefficients $1$, $-2x$, $-x^2$; their Wronskian determinants yield the Lie bracket. Likewise, the monomials $1$, $\ldots$, $x^k/k!$, $\ldots$, $x^N/N!$ span finite-dimensional strong homotopy (SH) Lie algebras with the Wronskians $\mathbf{1} \wedge \partial_x \wedge \ldots \wedge \partial_x^{N-1}$ as the $N$-ary brackets. Over dimension $d=2$ with $\mathbb{R}^2\ni(x,y)$ and for the generalised complete Wronskian $W^{d=2}_{k=1}=\mathbf{1}\wedge \partial_x \wedge \partial_y$ of differential order $k=1$ as the ternary bracket, the finite-dimensional polynomial SH-Lie algebras are spanned by $\langle 1$, $x$, $y$, $p\rangle$ with $p\in\{x^2$, $xy$, $y^2\}$. We explicitly describe all finite-dimensional polynomial SH-Lie algebras $\Bbbk_k[{\boldsymbol{x}}]\subseteq \mathcal{A} \subseteq \Bbbk[x^1,\ldots,x^d]$ (over $\Bbbk=\mathbb{R}$ or $\mathbb{C}$) with the complete generalised Wronskians $W^{d\geqslant 1}_{k\geqslant 1}$ of order $k$ as $N$-ary bracket: $N=\binom{d+k}{d}$. We obtain a factorisation formula for the generalised Vandermonde determinants which show up in the structure constants of the polynomial algebras $\mathcal{A}$.
通过自回归外生神经网络确定性地映射拓扑相
Graciana Puentes
AI总结 本文比较了三种动态神经网络架构(NAR、NARX、NIO),发现NARX架构在估计弱测量诱导几何相变中的临界测量强度参数时达到数值精度极限,揭示了缠绕数与临界参数之间的确定性关系。
我们报告了三种动态神经网络架构——NAR、NARX和NIO——的比较分析,以评估它们在估计表征弱测量诱导几何相中拓扑相变的临界测量强度参数($c_{crit}$)方面的效率。我们的结果表明,NARX架构在最优延迟$d=1$时实现了卓越的预测保真度,均方误差达到$10^{-27}$(数值精度极限)。这一非凡表现暗示了一个完美函数恒等式的识别,表明缠绕数$W$与$c_{crit}$之间的关系在数学上是确定性的。我们观察到一个“复杂性悖论”:NARX模型的准确性在更高延迟($d=4$)时崩溃,这种相位敏感性证实了模型捕捉的是高精度动态映射而非平凡模式。虽然NAR模型在局部趋势捕捉方面保持稳健,但NIO架构尽管增加了神经元容量,却未能准确解析相变。这些发现强调,自回归反馈和即时外生上下文对于拓扑相的精确表征都是必不可少的,从而将NARX确立为在解析解仍难以获得的复杂量子系统中推导控制定律的稳健框架。
We report a comparative analysis of three dynamic neural network (NN) architectures -- NAR, NARX, and NIO -- to evaluate their efficiency in estimating the critical-measurement-strength parameter ($c_{crit}$) characterizing topological phase transitions in geometric phases induced by weak measurements. Our results demonstrate that the NARX architecture achieves superior predictive fidelity, reaching a Mean Squared Error (MSE) of $10^{-27}$ -- the limit of numerical precision -- at an optimal delay of $d=1$. This exceptional performance implies the identification of a perfect functional identity, suggesting that the relationship between winding numbers $W$ and $c_{crit}$ is mathematically deterministic. We observe a "complexity paradox" where the NARX model's accuracy collapses at higher delays ($d=4$), a phase-sensitivity that confirms the model captures a high-precision dynamic mapping rather than a trivial pattern. While the NAR model remains robust for local-trend capture, the NIO architecture fails to accurately resolve the phase transition despite increased neuronal capacity. These findings underscore that both autoregressive feedback and immediate exogenous context are essential for the exact characterization of topological phases, establishing NARX as a robust framework for deriving governing laws in complex quantum systems, where analytical solutions remain elusive.
向列相环的几何与弛豫动力学
F. Aprile, A. J. H. Houston, G. Gonnella, D. Marenduzzo, T. N. Shendruk, G. Negro
AI总结 利用Clifford代数描述向列相液晶中向错环的几何轮廓,并揭示其动力学演化与拓扑链接的关系。
三维向列相液晶中的向错线通常形成闭合环,其拓扑由同伦论分类。虽然这种分类成功捕捉了全局拓扑特征,但它并未编码沿环的缺陷轮廓的几何形状,而这可以强烈影响缺陷动力学。在这里,我们提出使用Clifford代数Cl(3,0)对向列相向错环进行几何描述。该方法自然地捕捉了局部缺陷轮廓的几何形状,以及沿环的变化,这在数学上是SU(2)和乐。对嵌入向列相液晶中具有指定几何形状的缺陷环动力学的模拟表明,环会引发缺陷的“拓扑团块”生长,随后消散,留下均匀的向列相织构。缺陷轮廓的自扭转会导致额外的链接向错线的成核,总自扭转与链接数之间存在简单的算术关系。相反,具有偶数个离散轮廓转变的环会产生环间穿线的图案,但没有链接。这些结果建立了向错环的几何和乐与其后续演化之间的直接联系,并且可能扩展到更复杂的序参量流形,如胆甾相或近晶相。
Disclination lines in three-dimensional nematic liquid crystals generically form closed loops whose topology is classified by homotopy theory. While this classification successfully captures global topological features, it does not encode the geometry of the defect profile along the loop, which can strongly influence defect dynamics. Here, we propose a geometric description of nematic disclination loops using the Clifford algebra Cl(3,0). This approach naturally captures the geometry of the local defect profile, as well as changes along the loop, which is mathematically a SU(2) holonomy. Simulations of the dynamics of defect loops with specified geometries embedded in nematic liquid crystals demonstrate that loops nucleate the growth of "topological blobs" of defects, which later dissipate leaving uniform nematic textures. Self-twist of the defect profile leads to nucleation of additional linking disclination lines, with a simple arithmetic relation between total self-twist and linking number. In contrast, loops with an even number of discrete profile transitions generate patterns with threading between loops, but no linking. These results establish a direct connection between the geometric holonomy of a disclination loop and its subsequent evolution, and may be extendable to more complex order parameter manifolds, such as cholesterics or smectics.
海王星脊行星 WASP-156 b 并非极轨道
M. Lafarga, J. I. Espinoza-Retamal, H. M. Cegla, G. Stefánsson, A. V. Freckelton, A. Mortier, S. Gill, E. Ahrer, D. Anderson, D. J. Armstrong, J. L. Bean, V. Bourrier, M. Brady, M. Brogi, E. M. Bryant, M. R. Burleigh, L. Doyle, J. S. Jenkins, D. Kasper, X. Luo, L. Mancini, M. Moyano, S. Saha, J. Southworth, D. Veras, J. I. Vines, P. J. Wheatley, J. N. Winn
AI总结 通过分析 ESPRESSO 和 MAROON-X 的罗斯特-麦克劳林效应观测,发现 WASP-156 b 的轨道是共面的(λ=-8±16°),否定了先前高度倾斜轨道的结论,并更新了系统参数。
短周期系外海王星种群被认为是由不同动力学机制(如轨道迁移、潮汐效应和光蒸发)的相互作用塑造的。我们可以通过研究恒星倾角等可观测量来深入了解这些过程。本文研究了罗斯特-麦克劳林(RM)效应,并测量了海王星脊行星 WASP-156 b 的投影倾角 λ。我们分析了新的 ESPRESSO 和 MAROON-X 光谱凌星观测数据,以及同时进行的 NGTS 测光数据。我们的分析显示轨道是共面的(基于 ESPRESSO 观测,λ=-8±16°),这与先前高度倾斜轨道的报告相反。我们还通过谱线建模发现恒星的投影自转速度 v sin i_★ ≤ 2 km/s,通过 RM 建模得到 v sin i_★ = 0.40±0.11 km/s。这低于先前报告的约 4 km/s,这可以部分解释先前得出的极轨道。我们还更新了系统的轨道参数,并利用长期径向速度数据排除了 5 au 内存在木星质量伴星的可能性。该行星的共面且圆形轨道(3σ 下 e<0.16),以及附近缺乏大质量伴星,与原地形成或早期盘驱动迁移一致。我们的发现将 WASP-156 b 从极轨道近距离海王星的暂定星群转移到了共面海王星的星群中。
The population of short-period exo-Neptunes is thought to be shaped by an interplay between different dynamical mechanisms, such as orbital migration and tidal effects, and photoevaporation. We can gain insight into these processes by studying observables such as the stellar obliquity. Here we study the Rossiter-McLaughlin (RM) effect and measure the projected obliquity, $λ$, of the Neptunian ridge planet WASP-156 b. We analyse new ESPRESSO and MAROON-X spectroscopic transit observations, and new NGTS photometry simultaneous to the ESPRESSO data. Our analyses show an aligned orbit ($λ=-8\pm16^\circ$, based on the ESPRESSO observations), in contrast to a previous report of a highly misaligned orbit. We also find the star's projected rotational velocity to be $v \sin i_\mathrm{\star}\leq2$ km/s from spectral line modelling and $v \sin i_\mathrm{\star}=0.40\pm0.11$ km/s from the RM modelling. This is lower than the previously reported value of $\sim4$ km/s, which could partly explain the previously derived polar orbit. We also update the system's orbital parameters and rule out Jupiter-mass companions within 5 au using long-term radial velocity data. The planet's aligned and circular orbit ($e<0.16$ at $3σ$), and lack of nearby massive companions, are consistent with in situ formation or early disc-driven migration. Our findings move WASP-156 b from a tentative cluster of close-in Neptunes in polar orbits to the group of aligned Neptunes.
表面吸积盘中气体的重元素富集:系外行星质量-金属丰度反相关的一个可能起源
Yoshitaka Ikeda, Kazumasa Ohno, Satoshi Okuzumi
AI总结 本文提出表面吸积盘模型,通过缓慢漂移的脆弱冰尘在雪线内富集水汽,解释了系外行星大气金属丰度与行星质量的反相关关系。
最近的观测,包括JWST的观测,表明许多气态巨行星的大气具有超恒星金属丰度,且与行星质量呈反相关。多项研究表明,超恒星金属丰度可以通过快速漂移的冰卵石升华产生的蒸汽富集盘气体的吸积来解释。然而,最近的盘观测和实验表明,冰尘在低温下是脆弱的,这对冰粒高效生长并快速漂移的传统观点提出了质疑。我们提出了一个由脆弱、缓慢漂移的冰尘在内盘引起重元素富集的新场景,假设磁流体动力学盘风驱动气体吸积发生在盘表面而非中平面。我们模拟了表面吸积盘中气体和尘埃的演化,考虑了气体和尘埃的径向输运、脆弱尘埃的碰撞生长和破碎以及H2O的凝结和升华。提出了两种吸积盘模型,其中气体吸积流假设为垂直均匀或狭窄集中在盘表面。在均匀吸积盘模型中,由于缓慢漂移,脆弱冰粒仅将雪线内的水汽丰度提高了约3倍。相比之下,在表面吸积盘模型中,由于选择性去除盘中的无冰气体,冰尘的缓慢漂移导致水汽富集高出一个数量级。此外,表面吸积产生了内盘水汽浓度与残余盘气体质量之间的反相关,类似于在太阳系外巨行星中观察到的大气金属丰度与行星质量之间的反相关。
Recent observations, including those by JWST, suggest that the atmospheres of many gas giant exoplanets have super-stellar metallicity that is anti-correlated with planetary mass. Several studies suggest that the super-stellar metallicity can be explained by accretion of vapor-enriched disk gas produced by the sublimation of rapidly drifting icy pebbles. However, recent disk observations and experiments suggest that icy dust is fragile at low temperatures, calling into question the conventional picture that icy grains grow efficiently and drift rapidly. We present a new scenario for heavy-element enrichment in the inner disk by fragile, slowly drifting icy dust, assuming that magnetohydrodynamical disk winds drive gas accretion near the disk surface rather than at the midplane. We simulate the evolution of gas and dust in a surface-accretion disk, taking into account the radial transport of gas and dust, collision growth and fragmentation of fragile dust, and the condensation and sublimation of H2O. Two accretion disk models are presented, in which gas accretion flows are assumed to be either vertically uniform or narrowly concentrated near the disk surface. In the uniform accretion disk model, fragile icy grains enhance the water vapor abundance inside the snow line only by a factor of ${\sim}3$ due to their slow drift. In contrast, in the surface-accretion disk model, the slow drift of icy dust leads to water vapor enrichment that is higher by an order of magnitude, owing to the selective removal of ice-free gas from the disk. Furthermore, surface accretion yields an anti-correlation between the water vapor concentration in the inner disk and the residual disk gas mass, analogous to the anti-correlation between atmospheric metallicity and planet mass observed in extrasolar giant planets.
基自适应稀疏态量子电路模拟
Ch Nihar Kartikeya, Anjana K, Bijita Sarma, Sangkha Borah
AI总结 提出基自适应稀疏态模拟(BASS)算法,通过动态更新每个量子比特的局部表示基(基于自然轨道思想),在截断时保持振幅聚集,从而在固定稀疏预算下显著提高量子电路模拟的保真度。
多体量子系统的经典模拟仅在波函数振幅在工作基中保持局域化时才经济。固定基稀疏态模拟器通过保留最大计算基振幅,将内存缩放为 $\mathcal{O}(k)$;然而,一旦纠缠或基旋转将权重分布到希尔伯特空间,保真度就会下降。在这项工作中,我们引入了一种称为基自适应稀疏态模拟(BASS)的算法,该算法在执行过程中更新每个量子比特的局部表示基,而不是在整个电路中锁定计算基。在截断之前,每个量子比特被旋转到其单量子比特约化密度矩阵的本征基,遵循量子化学中的自然轨道思想,因此保留的振幅保持聚集。我们证明,在任何固定基中,top-$k$ 选择对于一步截断是唯一最优的,并且一体约化密度矩阵本征基是逆参与比(PR)的平稳乘积基,其残差由局域纠缠相干性界定。我们对各种量子电路进行了系统基准测试,并证明比值 $k/\text{PR}_Z$(稀疏预算与计算参与比之比)可作为自适应测量基提供性能优势的指标。在结构化砖墙电路上,BASS 实现了比固定基方法显著更高的保真度,同时在内存受限情况下仅适度增加墙钟时间。此外,对于无序伊辛电路,BASS 在固定计算预算下系统性地将状态重叠提高了大约一个数量级。
Classical simulation of many-body quantum systems remains economical only when wavefunction amplitudes stay localized in the working basis. Fixed-basis sparse-state simulators scale memory as $\mathcal{O}(k)$ by keeping the largest computational-basis amplitudes; however, fidelity drops once entanglement or basis rotations spread weight across the Hilbert space. In this work, we introduce an algorithm called Basis-Adaptive Sparse-State Simulation (BASS), which updates each qubit's local representation basis during execution rather than locking the computational basis for the entire circuit. Before truncation, each qubit is rotated into the eigenbasis of its single-qubit reduced density matrix, following the natural-orbital idea from quantum chemistry, so the retained amplitudes stay clustered. We prove that top-$k$ selection is uniquely optimal for one-step truncation in any fixed basis and that the one-body reduced-density-matrix eigenbasis is a stationary product basis for the inverse participation ratio (PR), with a residual bounded by local entanglement coherence. We perform a systematic benchmarking over a variety of quantum circuits and demonstrate that the ratio \(k/\text{PR}_Z\) (sparse budget over computational participation ratio) serves as an indicator for regimes in which adaptive measurement bases provide a performance advantage. On structured brickwork circuits, BASS achieves substantially higher fidelity than the fixed-basis approach, while incurring only a moderate increase in wall-clock time in the memory-limited regime. Moreover, for disordered Ising circuits, BASS systematically provides an improvement of approximately one order of magnitude in state overlap at a fixed computational budget.
带空间电荷的粒子加速器模拟中反向模式微分的记忆缩放
Arjun Dhamrait, Edoardo Zoni, Axel Huebl, Ji Qiang, Chad E. Mitchell, Ryan Roussel, Jan Kaiser, Chenran Xu, Jean-Luc Vay, Remi Lehe
AI总结 研究了基于PyTorch的束流追踪代码Cheetah中空间电荷计算对反向模式自动微分记忆使用的影响,发现记忆使用与宏粒子数、网格数及空间电荷踢数线性增长,可用于评估硬件内存约束下的模拟可行性。
最近,粒子加速器可微分模拟代码的发展使得基于梯度的流程成为可能,有望实现对加速器设施的更精细控制和更真实建模。然而,当使用反向模式自动微分时,模拟过程中内存使用持续增加,可能超过可用硬件内存——尤其是在包含昂贵的空间电荷计算时。为了研究可微分模拟的内存需求,我们在Cheetah(一个基于PyTorch、支持反向模式微分的束流追踪代码)中实现了空间电荷。我们发现,反向模式微分的内存使用随宏粒子和网格数量线性增长,并且与模拟中涉及的空间电荷踢数成正比。这种通用缩放可用于评估在给定硬件内存约束下,特定可微分模拟是否可行。
The recent development of differentiable simulation codes for particle accelerators has enabled gradient-based workflows that promise finer control and more realistic modeling of accelerator facilities. However, when using reverse-mode automatic differentiation, the memory usage continuously increases during the simulation, and can potentially exceed the available hardware memory -- especially when costly space charge computation is included. To study the memory requirements for differentiable simulations, we have implemented space charge in Cheetah, a PyTorch-based beam tracking code that supports reverse-mode differentiation. We find that the memory usage for reverse-mode differentiation grows linearly with the number of macroparticles and cells, and that it is proportional to the number of space charge kicks involved in the simulation. This general scaling can be used to evaluate whether a given differentiable simulation is feasible given hardware memory constraints.
三次轨道磁化的三个量子几何贡献
T. Farajollahpour
AI总结 本文通过Ward完备的有限动量三次Kubo核,将非中心对称金属中直流三次轨道磁化响应分解为三个量子几何通道,并提出了三次谐波磁光Kerr光谱作为实验探测方法。
在非中心对称金属中,例如$C_{3v}$拓扑绝缘体表面、莫尔异质双层和闪锌矿晶体,点群对称性可以禁止线性和二次电场诱导的轨道磁化,使得三次响应成为主导信号。使用具有反对称线性$q$投影的Ward完备有限动量三次Kubo核,我们展示了直流响应分解为三个量子几何通道。这些是混合电磁位置位移四极子、量子度量漂移项和轨道矩八极子。这三个贡献具有相同的点群对称性,但在寿命、频率和栅极指纹上有所不同。对于扭曲的$C_{3v}$表面,度量通道遵循截断无关定律$arχ_G \propto μ^{-2}$。我们提出三次谐波磁光Kerr光谱作为实验途径。
In noncentrosymmetric metals such as $C_{3v}$ topological-insulator surfaces, moiré heterobilayers, and zincblende crystals, point-group symmetry can forbid the linear and quadratic electric-field-induced orbital magnetization, leaving the cubic response as the leading signal. Using a Ward-complete finite-momentum cubic Kubo kernel with an antisymmetric linear-in-$q$ projection, we show that the dc response separates into three quantum-geometric channels. These are a mixed electric-magnetic positional-shift quadrupole, a quantum-metric drift term, and an orbital-moment octupole. The three contributions share the same point-group symmetry but differ in their lifetime, frequency, and gate fingerprints. For a warped $C_{3v}$ surface the metric channel obeys the cutoff-independent law $\barχ_G \propto μ^{-2}$. We propose third-harmonic magneto-optical Kerr spectroscopy as an experimental route.