编译|未玖
Nature, 17 April 2025, Volume 640, Issue 8059
《自然》2025年4月17日，第640卷，8059期
物理学Physics
Near-field photon entanglement in total angular momentum
总角动量中的近场光子纠缠
▲ 作者：Amit Kam, Shai Tsesses, Yigal Ilin, Kobi Cohen, Yaakov Lumer, Lior Fridman, et al.
▲ 链接： https://www.nature.com/articles/s41586-025-08761-1
▲ 摘要： 光子可以携带角动量，通常将其归因于两部分：自旋角动量（SAM）和轨道角动量（OAM），前者是与偏振相关的固有性质，后者与光子空间分布有关。
在近轴光学中，这两种形式的角动量是可分离的，因此可在单个光子的SAM和OAM之间或在多光子状态下的不同光子之间诱导纠缠。然而，在纳米光子系统中，光子的SAM和OAM是不可分离的，因此只有总角动量（TAM）可作为好的量子数。
研究组提出了两个光子在近场机制下的非经典相关性的观察，引发了与TAM相关的纠缠。他们通过将光子对耦合到等离子体模式来纠缠这些纳米光子态，并使用量子成像技术来测量其相关性。
研究组观察到，与两个组成角动量相关的纠缠相比，TAM中的纠缠导致光子对的量子关联结构完全不同。这项工作为利用光子的TAM作为量子信息的编码特性进行片上量子信息处理奠定了基础。
▲ Abstract： Photons can carry angular momentum, which is conventionally attributed to two constituents—spin angular momentum (SAM), which is an intrinsic property related to the polarization, and orbital angular momentum (OAM), which is related to the photon spatial distribution. In paraxial optics, these two forms of angular momentum are separable, such that entanglement can be induced between the SAM and the OAM of a single photon or of different photons in a multi-photon state. In nanophotonic systems, however, the SAM and the OAM of a photon are inseparable, so only the total angular momentum (TAM) serves as a good quantum number. Here we present the observation of non-classical correlations between two photons in the near-field regime, giving rise to entanglement related to the TAM. We entangle those nanophotonic states by coupling photon pairs to plasmonic modes and use quantum imaging techniques to measure their correlations. We observe that entanglement in TAM leads to a completely different structure of quantum correlations of photon pairs, compared with entanglement related to the two constituent angular momenta. This work paves the way for on-chip quantum information processing using the TAM of photons as the encoding property for quantum information.
材料科学Material Science
Observation of plastic ice VII by quasi-elastic neutron scattering
准弹性中子散射观测塑性冰VII
▲ 作者：Maria Rescigno, Alberto Toffano, Umbertoluca Ranieri, Leon Andriambariarijaona, Richard Gaal, Stefan Klotz, et al.
▲ 链接： https://www.nature.com/articles/s41586-025-08750-4
▲摘要：水是宇宙中第三丰富的分子，也是冰卫星、巨行星以及类天王星和类海王星系外行星内部的关键成分。由于水具有独特的分子结构和灵活的氢键，很容易适应大范围的压力和温度，水形成了许多结晶相和非晶相。
与行星内部的高压和高温最相关的是冰VII，模拟已确定了沿着其融化曲线存在所谓的塑性相，其中单个分子像在固体中一样占据固定位置，但又能像在液体中一样旋转。这种塑性冰尚未在实验中直接观测到。
研究组报道了在450至600 K的温度和高达6 GPa的压力下进行的准弹性中子散射测量，揭示了在冰VII中存在体心立方结构，水分子表现出典型液态水的皮秒旋转动力学。与分子动力学模拟的比较表明，这种塑性冰VII不符合自由转子相，而是表现出快速的定向跳跃，正如在跳跃转子塑性晶体中观察到的那样。
研究组预计，他们对塑性冰VII的观察将影响人们对冰行星地球动力学和大型冰卫星分化过程的理解。
▲ Abstract： Water is the third most abundant molecule in the universe and a key component in the interiors of icy moons, giant planets and Uranus- and Neptune-like exoplanets. Owing to its distinct molecular structure and flexible hydrogen bonds that readily adapt to a wide range of pressures and temperatures, water forms numerous crystalline and amorphous phases. Most relevant for the high pressures and temperatures of planetary interiors is ice VII, and simulations have identified along its melting curve the existence of a so-called plastic phase in which individual molecules occupy fixed positions as in a solid yet are able to rotate as in a liquid. Such plastic ice has not yet been directly observed in experiments. Here we present quasi-elastic neutron scattering measurements, conducted at temperatures between 450 and 600 K and pressures up to 6 GPa, that reveal the existence of a body-centred cubic structure, as found in ice VII, with water molecules showing picosecond rotational dynamics typical for liquid water. Comparison with molecular dynamics simulations indicates that this plastic ice VII does not conform to a free rotor phase but rather shows rapid orientational jumps, as observed in jump-rotor plastic crystals. We anticipate that our observation of plastic ice VII will affect our understanding of the geodynamics of icy planets and the differentiation processes of large icy moons.
人工智能Artificial Intelligence
Mastering diverse control tasks through world models
通过世界模型掌握不同的控制任务
▲ 作者：Danijar Hafner, Jurgis Pasukonis, Jimmy Ba & Timothy Lillicrap
▲ 链接： https://www.nature.com/articles/s41586-025-08744-2
▲摘要：开发一种通用算法，学习解决各种应用中的任务，一直是人工智能领域的一个基本挑战。尽管当前的强化学习算法可以很容易地应用于与算法所开发目的类似的任务，但将其配置到新应用领域需要大量的人类专业知识和实验。
研究组介绍了第三代Dreamer，这是一种通用算法，在超过150种不同的任务中，仅用单一的配置便胜过专业方法。Dreamer学习环境模型，并通过想象未来场景来改进其行为。基于规范化、平衡和转换的鲁棒性技术实现了跨领域的稳定学习。
据研究组所知，Dreamer能够开箱即用，是第一个在没有人工数据或课程的情况下，在《我的世界》游戏中从零开始收集钻石的算法。这一成就被视为攻克了人工智能领域的一项重大挑战，即需要在开放世界中从像素和稀疏奖励中探索有远见的策略。
该工作实现了在没有大量实验的情况下解决具有挑战性的控制问题，使强化学习具有广泛适用性。
▲ Abstract： Developing a general algorithm that learns to solve tasks across a wide range of applications has been a fundamental challenge in artificial intelligence. Although current reinforcement-learning algorithms can be readily applied to tasks similar to what they have been developed for, configuring them for new application domains requires substantial human expertise and experimentation. Here we present the third generation of Dreamer, a general algorithm that outperforms specialized methods across over 150 diverse tasks, with a single configuration. Dreamer learns a model of the environment and improves its behaviour by imagining future scenarios. Robustness techniques based on normalization, balancing and transformations enable stable learning across domains. Applied out of the box, Dreamer is, to our knowledge, the first algorithm to collect diamonds in Minecraft from scratch without human data or curricula. This achievement has been posed as a substantial challenge in artificial intelligence that requires exploring farsighted strategies from pixels and sparse rewards in an open world. Our work allows solving challenging control problems without extensive experimentation, making reinforcement learning broadly applicable.
化学Chemistry
Metal–support frontier orbital interactions in single-atom catalysis
单原子催化中的金属-载体前沿轨道相互作用
▲ 作者：Xianxian Shi, Zhilin Wen, Qingqing Gu, Long Jiao, Hai-Long Jiang, Haifeng Lv, et al.
▲ 链接： https://www.nature.com/articles/s41586-025-08747-z
▲ 摘要： 单原子催化剂（SACs）具有最大限度地利用金属和离散能级的特点，在多相催化、能量转换、环境科学和生物医学等领域有广泛的应用前景。SACs的活性和稳定性是由一对金属—吸附物和金属—载体的相互作用决定的。然而，理解这些相互作用及其在自然界的催化性能颇具挑战性。活性与金属原子电荷态的相关性经常得出有争议的结论。
研究组报道了钯（Pd1）SACs的活性与14种半导体中氧化物载体的最低未占据分子轨道（LUMO）的位置呈线性缩放关系。通过将载体粒径减小到几纳米来提高LUMO位置，可在乙炔半氢化过程中提升创纪录的高活性以及优异的稳定性。
研究结果表明，载体的LUMO升高减少了其与Pd1原子的最高占据分子轨道（HOMO）的能隙，从而促进了Pd1—载体轨道杂化以获得高稳定性，并进一步修正了锚定Pd1原子的LUMO，以增强Pd1—吸附物的高活性相互作用。这些发现与前沿分子轨道理论一致，为合理选择具有可预测活性的金属—载体对提供了一个通用描述符。
▲ Abstract： Single-atom catalysts (SACs) with maximized metal use and discrete energy levels hold promise for broad applications in heterogeneous catalysis, energy conversion, environmental science and biomedicine. The activity and stability of SACs are governed by the pair of metal–adsorbate and metal–support interactions. However, the understanding of these interactions with their catalytic performance in nature is challenging. Correlations of activity with the charge state of metal atoms have frequently reached controversial conclusions. Here we report that the activity of palladium (Pd1) SACs exhibits a linear scaling relationship with the positions of the lowest unoccupied molecular orbital (LUMO) of oxide supports across 14 types of semiconductor. Elevation of the LUMO position by reducing the support particle size to a few nanometres boosts a record high activity along with excellent stability in the semi-hydrogenation of acetylene. We show that the elevated LUMO of support reduces its energy gap with the highest occupied molecular orbital (HOMO) of Pd1 atoms, which promotes Pd1–support orbital hybridizations for high stability and further amends the LUMO of anchored Pd1 atoms to enhance Pd1–adsorbate interactions for high activity. These findings are consistent with the frontier molecular orbital theory and provide a general descriptor for the rational selection of metal–support pairs with predictable activity.
Supramolecular docking structure determination of alkyl-bearing molecules
含烷基链分子的超分子对接结构测定
▲ 作者：Yitao Wu, Le Shi, Lei Xu, Jiale Ying, Xiaohe Miao, Bin Hua, et al.
▲ 链接： https://www.nature.com/articles/s41586-025-08833-2
▲ 摘要： 许多天然产物和药物都含有柔性烷基链。由此产生的构象运动可能增加单晶的获取难度，亦很难通过单晶X射线衍射（SCXRD）确定其分子结构。
研究组证明了通过使用柱[5]芳烃—金属有机框架（MOF）并利用柱[5]芳烃—烷基链的主—客体识别，有望减少这种运动，并通过在整体MOF中可接触柱[5]芳烃单元内对接，使含烷基链分子有序。
这实现了48个含烷基链分子（包括6种天然产物、2种批准药物和来自16个研究组的18种定制化合物）的单晶结构可通过标准SCXRD仪器进行确定。从粗反应产物中衍生的含烷基链分子的结构也可以通过SCXRD分析直接确定，而无需进一步纯化。
这种基于柱[5]芳烃—MOF的超分子对接方法具有简单、高效和通用性强等优势，可作为不适用于传统基于SCXRD结构测定法的天然产物和药物分析的新工具。
▲ Abstract： Numerous natural products and drugs contain flexible alkyl chains. The resulting conformational motion can create challenges in obtaining single crystals and thus determining their molecular structures by single-crystal X-ray diffraction (SCXRD). Here we demonstrate that by using pillar[5]arene-incorporated metal–organic frameworks (MOFs) and taking advantage of pillar[5] arene alkyl chain host guest recognition, it is possible to reduce this motion and bring order to alkyl-chain-containing molecules as the result of docking within accessible pillar[5]arene units present in an overall MOF. This has allowed the single-crystal structures of 48 alkyl-chain-containing molecules, including 6 natural products, 2 approved drugs and 18 custom-made compounds collected from 16 research groups, to be determined using standard SCXRD instrumentation. The structures of alkyl-chain-containing molecules derived from crude reaction products can also be determined directly by SCXRD analyses without further purification. The simplicity, high efficiency and apparent generality of the present pillar[5]arene-incorporated MOF-based supramolecular docking approach suggest that it could emerge as a new tool for the analyses of natural products and drugs that might not be amenable to traditional SCXRD-based structure determination.
地球科学Earth Science
Seismic imaging of a basaltic Lesser Antilles slab from ancient tectonics
古构造下小安的列斯玄武岩板块的地震成像
▲ 作者：Xusong Yang, Yujiang Xie, Catherine A. Rychert, Nicholas Harmon, Saskia Goes, Andreas Rietbrock, et al.
▲ 链接： https://www.nature.com/articles/s41586-025-08754-0
▲ 摘要： 在俯冲带，岩石圈物质通过上地幔下降到地幔过渡带（MTZ），在那里其可能继续下沉到下地幔或停滞。影响这种流动的几个因素可能很重要，包括化学非均质性。然而，探究这些地幔流动的严格限制和影响流动的确切因素颇具挑战性。 研究组使用P-to-S接收器函数对小安的列斯俯冲带下的俯冲板块和MTZ进行成像。他们在板块内200千米宽的区域内拍摄了一个异常加深（＞700千米）660千米的不连续面，并伴有附近的双660不连续面相（正常和超深）。 结合地球动力学和波形建模表明，这一观测结果不能用典型地幔成分的温度效应来解释，而必须存在一个富含玄武岩的大型化学异常区，在660深的异常位置最强。推断出的玄武岩特征靠近一个俯冲消亡扩张脊的位置，该区域玄武岩富集程度更高。 该发现表明，过去的构造事件赋予了板块化学非均质性，而这种非均质性反过来又可能影响板块下沉的固有趋势。
▲ Abstract： At subduction zones, lithospheric material descends through the upper mantle to the mantle transition zone (MTZ), where it may continue to sink into the lower mantle or stagnate. Several factors may be important in influencing this flow, including chemical heterogeneity. However, tight constraints on these mantle flows and the exact factors that affect them have proved challenging. We use P-to-S receiver functions to image the subducting slab and the MTZ beneath the Lesser Antilles subduction zone. We image a singular, superdeep (>700 km) 660-km discontinuity over a 200-km-wide zone within the slab, accompanied by nearby double 660 discontinuity phases (normal and superdeep). Combined geodynamic and waveform modelling shows that this observation cannot be explained by temperature effects in typical mantle compositions but requires a large basalt-rich chemical anomaly, strongest in the location of the singular, deep 660. The inferred basalt signature is near the proposed location of a subducted extinct spreading ridge, where basalt is probably present in greater proportions. Our finding suggests that past tectonic events impart chemical heterogeneity into slabs, and the heterogeneities, in turn, may affect the inherent tendency of the slab to sink.
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