編譯|未玖
Nature, 17 April 2025, Volume 640, Issue 8059
《自然》2025年4月17日，第640卷，8059期
物理學Physics
Near-field photon entanglement in total angular momentum
總角動量中的近場光子糾纏
▲ 作者：Amit Kam, Shai Tsesses, Yigal Ilin, Kobi Cohen, Yaakov Lumer, Lior Fridman, et al.
▲ 鏈接： https://www.nature.com/articles/s41586-025-08761-1
▲ 摘要： 光子可以攜帶角動量，通常將其歸因于兩部分：自旋角動量（SAM）和軌道角動量（OAM），前者是與偏振相關的固有性質，后者與光子空間分布有關。
在近軸光學中，這兩種形式的角動量是可分離的，因此可在單個光子的SAM和OAM之間或在多光子狀態下的不同光子之間誘導糾纏。然而，在納米光子系統中，光子的SAM和OAM是不可分離的，因此只有總角動量（TAM）可作為好的量子數。
研究組提出了兩個光子在近場機制下的非經典相關性的觀察，引發了與TAM相關的糾纏。他們通過將光子對耦合到等離子體模式來糾纏這些納米光子態，并使用量子成像技術來測量其相關性。
研究組觀察到，與兩個組成角動量相關的糾纏相比，TAM中的糾纏導致光子對的量子關聯結構完全不同。這項工作為利用光子的TAM作為量子信息的編碼特性進行片上量子信息處理奠定了基礎。
▲ 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.
材料科學Material Science
Observation of plastic ice VII by quasi-elastic neutron scattering
準彈性中子散射觀測塑性冰VII
▲ 作者：Maria Rescigno, Alberto Toffano, Umbertoluca Ranieri, Leon Andriambariarijaona, Richard Gaal, Stefan Klotz, et al.
▲ 鏈接： https://www.nature.com/articles/s41586-025-08750-4
▲摘要：水是宇宙中第三豐富的分子，也是冰衛星、巨行星以及類天王星和類海王星系外行星內部的關鍵成分。由于水具有獨特的分子結構和靈活的氫鍵，很容易適應大范圍的壓力和溫度，水形成了許多結晶相和非晶相。
與行星內部的高壓和高溫最相關的是冰VII，模擬已確定了沿著其融化曲線存在所謂的塑性相，其中單個分子像在固體中一樣占據固定位置，但又能像在液體中一樣旋轉。這種塑性冰尚未在實驗中直接觀測到。
研究組報道了在450至600 K的溫度和高達6 GPa的壓力下進行的準彈性中子散射測量，揭示了在冰VII中存在體心立方結構，水分子表現出典型液態水的皮秒旋轉動力學。與分子動力學模擬的比較表明，這種塑性冰VII不符合自由轉子相，而是表現出快速的定向跳躍，正如在跳躍轉子塑性晶體中觀察到的那樣。
研究組預計，他們對塑性冰VII的觀察將影響人們對冰行星地球動力學和大型冰衛星分化過程的理解。
▲ 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
通過世界模型掌握不同的控制任務
▲ 作者：Danijar Hafner, Jurgis Pasukonis, Jimmy Ba & Timothy Lillicrap
▲ 鏈接： https://www.nature.com/articles/s41586-025-08744-2
▲摘要：開發一種通用算法，學習解決各種應用中的任務，一直是人工智能領域的一個基本挑戰。盡管當前的強化學習算法可以很容易地應用于與算法所開發目的類似的任務，但將其配置到新應用領域需要大量的人類專業知識和實驗。
研究組介紹了第三代Dreamer，這是一種通用算法，在超過150種不同的任務中，僅用單一的配置便勝過專業方法。Dreamer學習環境模型，并通過想象未來場景來改進其行為。基于規范化、平衡和轉換的魯棒性技術實現了跨領域的穩定學習。
據研究組所知，Dreamer能夠開箱即用，是第一個在沒有人工數據或課程的情況下，在《我的世界》游戲中從零開始收集鉆石的算法。這一成就被視為攻克了人工智能領域的一項重大挑戰，即需要在開放世界中從像素和稀疏獎勵中探索有遠見的策略。
該工作實現了在沒有大量實驗的情況下解決具有挑戰性的控制問題，使強化學習具有廣泛適用性。
▲ 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.
化學Chemistry
Metal–support frontier orbital interactions in single-atom catalysis
單原子催化中的金屬-載體前沿軌道相互作用
▲ 作者：Xianxian Shi, Zhilin Wen, Qingqing Gu, Long Jiao, Hai-Long Jiang, Haifeng Lv, et al.
▲ 鏈接： https://www.nature.com/articles/s41586-025-08747-z
▲ 摘要： 單原子催化劑（SACs）具有最大限度地利用金屬和離散能級的特點，在多相催化、能量轉換、環境科學和生物醫學等領域有廣泛的應用前景。SACs的活性和穩定性是由一對金屬—吸附物和金屬—載體的相互作用決定的。然而，理解這些相互作用及其在自然界的催化性能頗具挑戰性。活性與金屬原子電荷態的相關性經常得出有爭議的結論。
研究組報道了鈀（Pd1）SACs的活性與14種半導體中氧化物載體的最低未占據分子軌道（LUMO）的位置呈線性縮放關系。通過將載體粒徑減小到幾納米來提高LUMO位置，可在乙炔半氫化過程中提升創紀錄的高活性以及優異的穩定性。
研究結果表明，載體的LUMO升高減少了其與Pd1原子的最高占據分子軌道（HOMO）的能隙，從而促進了Pd1—載體軌道雜化以獲得高穩定性，并進一步修正了錨定Pd1原子的LUMO，以增強Pd1—吸附物的高活性相互作用。這些發現與前沿分子軌道理論一致，為合理選擇具有可預測活性的金屬—載體對提供了一個通用描述符。
▲ 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
含烷基鏈分子的超分子對接結構測定
▲ 作者：Yitao Wu, Le Shi, Lei Xu, Jiale Ying, Xiaohe Miao, Bin Hua, et al.
▲ 鏈接： https://www.nature.com/articles/s41586-025-08833-2
▲ 摘要： 許多天然產物和藥物都含有柔性烷基鏈。由此產生的構象運動可能增加單晶的獲取難度，亦很難通過單晶X射線衍射（SCXRD）確定其分子結構。
研究組證明了通過使用柱[5]芳烴—金屬有機框架（MOF）并利用柱[5]芳烴—烷基鏈的主—客體識別，有望減少這種運動，并通過在整體MOF中可接觸柱[5]芳烴單元內對接，使含烷基鏈分子有序。
這實現了48個含烷基鏈分子（包括6種天然產物、2種批準藥物和來自16個研究組的18種定制化合物）的單晶結構可通過標準SCXRD儀器進行確定。從粗反應產物中衍生的含烷基鏈分子的結構也可以通過SCXRD分析直接確定，而無需進一步純化。
這種基于柱[5]芳烴—MOF的超分子對接方法具有簡單、高效和通用性強等優勢，可作為不適用于傳統基于SCXRD結構測定法的天然產物和藥物分析的新工具。
▲ 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.
地球科學Earth Science
Seismic imaging of a basaltic Lesser Antilles slab from ancient tectonics
古構造下小安的列斯玄武巖板塊的地震成像
▲ 作者：Xusong Yang, Yujiang Xie, Catherine A. Rychert, Nicholas Harmon, Saskia Goes, Andreas Rietbrock, et al.
▲ 鏈接： https://www.nature.com/articles/s41586-025-08754-0
▲ 摘要： 在俯沖帶，巖石圈物質通過上地幔下降到地幔過渡帶（MTZ），在那里其可能繼續下沉到下地幔或停滯。影響這種流動的幾個因素可能很重要，包括化學非均質性。然而，探究這些地幔流動的嚴格限制和影響流動的確切因素頗具挑戰性。 研究組使用P-to-S接收器函數對小安的列斯俯沖帶下的俯沖板塊和MTZ進行成像。他們在板塊內200千米寬的區域內拍攝了一個異常加深（＞700千米）660千米的不連續面，并伴有附近的雙660不連續面相（正常和超深）。 結合地球動力學和波形建模表明，這一觀測結果不能用典型地幔成分的溫度效應來解釋，而必須存在一個富含玄武巖的大型化學異常區，在660深的異常位置最強。推斷出的玄武巖特征靠近一個俯沖消亡擴張脊的位置，該區域玄武巖富集程度更高。 該發現表明，過去的構造事件賦予了板塊化學非均質性，而這種非均質性反過來又可能影響板塊下沉的固有趨勢。
▲ 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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