编译|未玖

Nature, 6 March 2025, Volume 639, Issue 8053

《自然》2025年3月6日，第639卷，8053期

天文学Astronomy

Real-time inference for binary neutron star mergers using machine learning

利用机器学习对双中子星合并进行实时推论

▲ 作者：Maximilian Dax, Stephen R. Green, Jonathan Gair, Nihar Gupte, Michael Pürrer, Vivien Raymond, et al.

▲链接：

https://www.nature.com/articles/s41586-025-08593-z

▲摘要：

双中子星的合并会同时发射引力波（GW）和电磁波谱信号。众所周知，2017年对GW170817的多信使观测导致了宇宙学、核物理学和引力领域的科学发现。这些结果的核心是从GW数据（如GW170817）中获得的天空定位和距离，这有助于识别GW信号发出后11小时的相关电磁瞬变，即AT 2017gfo。

快速分析GW数据对于指导时间敏感的电磁观测至关重要。然而，由于信号长度和复杂性带来的挑战，通常需要做出牺牲精度的近似值。

研究组提出了一个机器学习框架，可以在短短1秒内执行完整的双中子星推理，而无需引入近似假设。该方法通过提供以下优势来增强多信使观测：（1）即使在合并之前也能精确定位；（2）与近似低延迟方法相比，定位精度提高30%左右；（3）详细的光度距离、倾角和质量信息，可用来优先考虑昂贵的望远镜时间。

此外，该方法的灵活性和降低的成本为状态方程研究开辟了新的机会。最后，研究组证明了该方法可扩展到长达一小时的长信号，从而为下一代地面和空基探测器数据分析提供了蓝图。

▲ Abstract：

Mergers of binary neutron stars emit signals in both the gravitational-wave (GW) and electromagnetic spectra. Famously, the 2017 multi-messenger observation of GW170817 led to scientific discoveries across cosmology, nuclear physics and gravity. Central to these results were the sky localization and distance obtained from the GW data, which, in the case of GW170817, helped to identify the associated electromagnetic transient, AT 2017gfo, 11 h after the GW signal. Fast analysis of GW data is critical for directing time-sensitive electromagnetic observations. However, owing to challenges arising from the length and complexity of signals, it is often necessary to make approximations that sacrifice accuracy. Here we present a machine-learning framework that performs complete binary neutron star inference in just 1 s without making any such approximations. Our approach enhances multi-messenger observations by providing: (1) accurate localization even before the merger; (2) improved localization precision by around 30% compared to approximate low-latency methods; and (3) detailed information on luminosity distance, inclination and masses, which can be used to prioritize expensive telescope time. Additionally, the flexibility and reduced cost of our method open new opportunities for equation-of-state studies. Finally, we demonstrate that our method scales to long signals, up to an hour in length, thus serving as a blueprint for data analysis for next-generation ground- and space-based detectors.

物理学Physics

Orbital hybridization in graphene-based artificial atoms

石墨烯基人造原子的轨道杂化

▲ 作者：Yue Mao, Hui-Ying Ren, Xiao-Feng Zhou, Hao Sheng, Yun-Hao Xiao, Yu-Chen Zhuang, et al.

▲链接：

https://www.nature.com/articles/s41586-025-08620-z

▲摘要：

原子内部轨道杂化和原子间键的形成是真实原子凝聚形成物质的两个基本过程。人造原子通过展示可归因于量子约束的离散能级来模拟真实原子。因此，人造原子为模拟原子内轨道杂化和原子间键形成提供了一种固态模拟。人们在各种人造原子中广泛观察到原子间键形成的特征。然而，人造原子中原子内轨道杂化的直接证据仍有待实验证明。

研究组通过改变人造原子的形状来实现人造原子的轨道杂化。约束势的各向异性引起了人造原子内不同轨道量子数的准束缚态之间的杂化。在该实验中，这些杂化轨道在真实空间中直接可视化，并通过数值计算和分析推导得到了很好的再现。

该研究为设计无法通过实验在真实原子上获得的人造物质开辟了一条途径。此外，所得结果启发了对不同系统中量子态的渐进控制。

▲ Abstract：

Intra-atomic orbital hybridization and interatomic bond formation are the two fundamental processes when real atoms are condensed to form matter. Artificial atoms mimic real atoms by demonstrating discrete energy levels attributable to quantum confinement. As such, they offer a solid-state analogue for simulating intra-atomic orbital hybridization and interatomic bond formation. Signatures of interatomic bond formation have been extensively observed in various artificial atoms. However, direct evidence of the intra-atomic orbital hybridization in the artificial atoms remains to be experimentally demonstrated. Here we realize the orbital hybridization in artificial atoms by altering the shape of the artificial atoms. The anisotropy of the confining potential gives rise to the hybridization between quasibound states with different orbital quantum numbers within the artificial atom. These hybridized orbits are directly visualized in real space in our experiment and are well reproduced by both numerical calculations and analytical derivations. Our study opens an avenue for designing artificial matter that cannot be accessed on real atoms through experiments. Moreover, the results obtained inspire the progressive control of quantum states in diverse systems.

Interplay of geometrical and spin chiralities in 3D twisted magnetic ribbons

三维扭曲磁性带中几何手性和自旋手性的相互作用

▲ 作者：André M. A. Farinha, See-Hun Yang, Jiho Yoon, Banabir Pal & Stuart S. P. Parkin

▲链接：

https://www.nature.com/articles/s41586-024-08582-8

▲摘要：

手性是自然界中普遍存在的基本不对称性。近年来，手性物体与自旋电流的相互作用引起了科学和技术领域的极大关注。特别令人感兴趣的是手性拓扑激发的电流驱动运动，例如手性三维磁性结构中的手性磁畴壁，可实现高密度存储设备。

研究组使用最先进的多光子光刻技术来创建三维手性磁性带，并进行手性畴壁的电流感应运动。这些带子被设计成具有可变幅度的顺时针或逆时针手性扭曲。结果发现畴壁可以穿过带子或受阻，这取决于其手性和构型以及带子的几何手性扭曲。

磁交换能量和几何扭曲之间的相互作用产生了一个有利于手性布洛赫型壁的扭转场，而不是由磁性带本身的固有磁性所支持的奈尔型壁。此外，自旋手性和手性扭曲的相互作用导致了非互易畴壁运动，即畴壁滤波器或二极管。

该发现表明几何手性和自旋手性之间的相互作用可产生新的物理效应，从而实现创新的手性自旋电子学。

▲ Abstract：

Chirality is a ubiquitous and fundamental asymmetry in nature. Recently, the interaction of chiral objects with spin currents has attracted enormous attention from both scientific and technological perspectives. Of particular interest is the current-driven motion of chiral topological excitations such as chiral magnetic domain walls in chiral three-dimensional magnetic structures that could allow for high-density memory-storage devices. Here we use state-of-the-art multiphoton lithography to create three-dimensional chiral magnetic ribbons and perform current-induced motion of chiral domain walls. The ribbons are designed to have a clockwise or anticlockwise chiral twist with a variable magnitude. We find that domain walls can either pass through the ribbon or are impeded, depending on their chirality and configuration and the geometrical chiral twist of the ribbon. The interplay between the magnetic exchange energy and the geometrical twist generates a torsional field that favours chiral Bloch-type walls rather than the Néel-type wall favoured by the intrinsic magnetic properties of the magnetic ribbon itself. Furthermore, the interplay of spin chirality and chiral twist results in a non-reciprocal domain wall motion, namely, a domain wall filter or diode. Our findings show how the interplay between geometrical and spin chiralities can lead to new functionalities that could allow for innovative chiral spintronics.

材料科学Materials Science

Steering perovskite precursor solutions for multijunction photovoltaics

调控钙钛矿前驱体溶液制备多结光伏电池

▲ 作者：Shuaifeng Hu, Junke Wang, Pei Zhao, Jorge Pascual, Jianan Wang, Florine Rombach, et al.

▲链接：

https://www.nature.com/articles/s41586-024-08546-y

▲摘要：

多结光伏电池（PV）因其超越单结电池辐射极限功率转换效率（PCE）的优越能力而日益突出，为此改善窄带隙（NBG）锡铅钙钛矿对薄膜器件至关重要。

研究组重点分析了锡铅钙钛矿前驱体溶液的化学性质，发现Sn（II）物种主导了与前驱体和添加剂的相互作用，揭示了羧酸在调节溶液胶体性质和薄膜结晶方面的独特作用，以及铵在改善薄膜光电性能方面的独特作用。结合这两种官能团（氨基酸盐）的材料大大提高了钙钛矿薄膜的半导体质量和均匀性，超过了单个官能团作为单独分子的一部分引入时的效果。

研究组的增强锡铅钙钛矿层实现了制造PCE分别为23.9%、29.7%（认证为29.26%）和28.7%的单结、双结和三结器件的太阳能电池。该1 cm2三结器件的PCE为28.4%（认证为27.28%）。封装的三结电池在标准测试条件下进行最大功率点跟踪（MPPT）860小时后仍保持80%的初始效率。

研究组进一步制备了四结器件，获得了27.9%的PCE，最高开路电压为4.94 V。这项工作为多结PV建立了一个新基准。

▲ Abstract：

Multijunction photovoltaics (PVs) are gaining prominence owing to their superior capability of achieving power conversion efficiencies (PCEs) beyond the radiative limit of single-junction cells, for which improving narrow-bandgap (NBG) tin–lead perovskites is critical for thin-film devices. Here, with a focus on understanding the chemistry of tin–lead perovskite precursor solutions, we find that Sn(II) species dominate interactions with precursors and additives and uncover the exclusive role of carboxylic acid in regulating solution colloidal properties and film crystallization and ammonium in improving film optoelectronic properties. Materials that combine these two functional groups, amino acid salts, considerably improve the semiconducting quality and homogeneity of perovskite films, surpassing the effect of the individual functional groups when introduced as part of separate molecules. Our enhanced tin–lead perovskite layer allows us to fabricate solar cells with PCEs of 23.9%, 29.7% (certified 29.26%) and 28.7% for single-junction, double-junction and triple-junction devices, respectively. Our 1-cm2triple-junction devices show PCEs of 28.4% (certified 27.28%). Encapsulated triple-junction cells maintain 80% of their initial efficiencies after 860 h maximum power point tracking (MPPT) in ambient. We further fabricate quadruple-junction devices and obtain PCEs of 27.9% with the highest open-circuit voltage of 4.94 V. This work establishes a new benchmark for multijunction PVs.

机械工程Mechanical Engineering

Achieving kilowatt-scale elastocaloric cooling by a multi-cell architecture

多单元结构助力千瓦级弹性热冷却

▲ 作者：Guoan Zhou, Lingyun Zhang, Zexi Li, Peng Hua, Qingping Sun & Shuhuai Yao

▲链接：

https://www.nature.com/articles/s41586-024-08549-9

▲摘要：

使用形状记忆合金（SMA）的弹性热冷却作为一种环保、节能的传统蒸汽压缩制冷替代方案，引起了人们极大的兴趣。然而，现有设备的有限冷却功率（≤300W）阻碍了该技术的商业化。

研究组使用薄壁压缩管状镍钛在“SMA串联—流体并联”架构中构建了一个千瓦级的弹性热冷却装置，称为多单元架构。在高频操作（3.5 Hz）下，薄壁管状镍钛具有较大的比表面积，并辅以石墨烯纳米流体作为高效传热剂，从而实现了12.3 W g?1的大比冷却功率。

此外，多单元结构确保了足够的弹性热质量，以实现紧密组装，同时保持较低的系统流体压力。在最初的50万次循环中，该设备在零温差下实现了1284W的冷却功率，展示了这种绿色冷却技术在脱碳未来的潜力。

▲ Abstract：

Elastocaloric cooling using shape memory alloys (SMAs) has attracted considerable interest as an environmentally friendly, energy-efficient alternative to conventional vapour-compression refrigeration. However, the limited cooling power of existing devices (≤300 W) hampers the commercialization of this technology. Here we constructed a kilowatt-scale elastocaloric cooling device using compressive tubular NiTi in an ‘SMAs in series–fluid in parallel’ architecture, referred to as the multi-cell architecture. A large specific cooling power of 12.3 W g?1was achieved by the large surface-area-to-volume ratio of thin-walled tubular NiTi at high-frequency operation (3.5 Hz), complemented by graphene nanofluid as an efficient heat transfer agent. Furthermore, the multi-cell architecture ensures a sufficient elastocaloric mass for tight assembly while maintaining a low system fluid pressure. Our device achieves a cooling power of 1,284 W on the fluid side at zero temperature lift during the initial 500,000 cycles, demonstrating the potential of this green cooling technology for a decarbonized future.

地球科学Earth Science

Glacial isostatic adjustment reveals Mars’s interior viscosity structure

冰川均衡调整揭示了火星内部的粘度结构

▲ 作者：A. Broquet, A.-C. Plesa, V. Klemann, B. C. Root, A. Genova, M. A. Wieczorek, et al.

▲链接：

https://www.nature.com/articles/s41586-024-08565-9

▲摘要：

研究冰川均衡调整一直是揭示地球内部粘度结构的标准方法，但由于缺乏观测数据，这种方法很少应用于其他行星。火星的北极冰盖是唯一一个有数百万年历史的地表特征，可在火星上引起可测量的地表变形，从而为其目前的内部粘度结构提供线索。

研究组采用热演化模型、粘弹性变形计算和雷达观测相结合的方法研究了该冰盖的定位过程。结果表明，北部地区的沉降运动持续进行，并且可以通过分析时变重力场和美国宇航局的洞察号地震矩率来约束。

只有现今高粘度（深度大于500千米时为2~6×1022Pa s）、放射性成因元素的强烈地幔耗竭（超过90%）和厚平均地壳（厚度大于40千米）的模式与雷达观测到的北极冰盖下可忽略的变形一致。北部岩石圈的变形速度必须小于0.13 mm /年，地震能量释放效率必须小于0.3，才能分别满足重力和地震约束。

该模型表明，北极冰盖形成于过去的170~1200万年，冰川均衡调整可能会受到未来火星重力恢复任务的进一步约束。

▲ Abstract：

Investigating glacial isostatic adjustment has been the standard method to decipher Earth’s interior viscosity structure, but such an approach has been rarely applied to other planets because of a lack of observational data. The north polar cap of Mars is the only millions-of-years-old surface feature that can induce measurable surface deformation on this planet, thereby holding clues to its present-day internal viscosity structure. Here we investigate the emplacement of this ice cap by combining thermal evolution models, viscoelastic deformation calculations and radar observations. We show that downward motion of the northern regions is ongoing and can be constrained by analyses of the time-variable gravity field and NASA’s InSight seismic moment rate. Only models with present-day high viscosities (2–6 ×1022Pa s for depths greater than 500 km), strong mantle depletion in radiogenic elements (more than 90%) and thick average crusts (thicker than 40 km) are consistent with the negligible flexure beneath the polar cap seen by radars. The northern lithosphere must deform at less than 0.13 mm per year and have a seismic efficiency less than 0.3 to satisfy gravity and seismic constraints, respectively. Our models show that the north polar cap formed over the last 1.7–12.0 Myr and that glacial isostatic adjustment can be further constrained by future gravity recovery missions to Mars.