《自然》（20250327出版）一周論文導(dǎo)讀
編譯|未玖
Nature, 27 March 2025, Volume 639, Issue 8056
《自然》2025年3月27日，第639卷，8056期
天文學(xué)Astronomy
Witnessing the onset of reionization through Lyman-α emission at redshift 13
紅移13處的萊曼-α發(fā)射見(jiàn)證再電離的開(kāi)始
▲ 作者：Joris Witstok, Peter Jakobsen, Roberto Maiolino, Jakob M. Helton, Benjamin D. Johnson, Brant E. Robertson, et al.
▲鏈接：
https://www.nature.com/articles/s41586-025-08779-5
▲摘要：
宇宙再電離始于首批星系產(chǎn)生的紫外線（UV）輻射照亮充斥著原始宇宙的冷中性氣體之時(shí)。詹姆斯·韋伯太空望遠(yuǎn)鏡（JWST）的最新觀測(cè)表明，在宇宙年齡不足3億年時(shí)，就有驚人的紫外明亮星系存在于紅移z=14之外的區(qū)域。
這些星系紫外線連續(xù)譜的平滑翻轉(zhuǎn)被解釋為中性氫躍遷的萊曼-α（Ly-α）阻尼翼吸收。然而，這些來(lái)源的關(guān)鍵特性（如其逃逸輻射場(chǎng)）在很大程度上仍難以捉摸。
研究組報(bào)告了來(lái)自JWST深空星系外觀測(cè)（JADES）對(duì)一個(gè)紅移z=13.0星系的光譜學(xué)觀測(cè)結(jié)果，其呈現(xiàn)出一條獨(dú)特的明亮發(fā)射線，明確被識(shí)別為L(zhǎng)y-α，以及一個(gè)平滑翻轉(zhuǎn)。
他們觀測(cè)到EWLy-α的等效寬度>40A（靜止幀），此前僅在星系間介質(zhì)電離程度較高的z<9區(qū)域普遍觀測(cè)到。結(jié)合極藍(lán)的紫外線連續(xù)譜，意外的Ly-α 發(fā)射表明該星系是大量產(chǎn)生和泄漏電離光子的源頭。
這表明，大質(zhì)量、熾熱的恒星或活躍星系核創(chuàng)建了一個(gè)早期再電離區(qū)域，從而阻止了Ly-α線的完全消失，這為最早期星系的性質(zhì)以及大爆炸后僅3.3億年就已存在局部再電離區(qū)域提供了新見(jiàn)解。
▲ Abstract：
Cosmic reionization began when ultraviolet (UV) radiation produced in the first galaxies began illuminating the cold, neutral gas that filled the primordial Universe. Recent James Webb Space Telescope (JWST) observations have shown that surprisingly UV-bright galaxies were in place beyond redshift z?=?14, when the Universe was less than 300?Myr old. Smooth turnovers of their UV continua have been interpreted as damping-wing absorption of Lyman-α (Ly-α), the principal hydrogen transition. However, spectral signatures encoding crucial properties of these sources, such as their emergent radiation field, largely remain elusive. Here we report spectroscopy from the JWST Advanced Deep Extragalactic Survey (JADES) of a galaxy at redshift z?=?13.0 that reveals a singular, bright emission line unambiguously identified as Ly-α, as well as a smooth turnover. We observe an equivalent width of EWLy-α?>?40?? (rest frame), previously only seen at z?<?9 where the intervening intergalactic medium becomes increasingly ionized. Together with an extremely blue UV continuum, the unexpected Ly-α emission indicates that the galaxy is a prolific producer and leaker of ionizing photons. This suggests that massive, hot stars or an active galactic nucleus have created an early reionized region to prevent complete extinction of Ly-α, thus shedding new light on the nature of the earliest galaxies and the onset of reionization only 330?Myr after the Big Bang.
Vertical structure of an exoplanet’s atmospheric jet stream
系外行星大氣急流的垂直結(jié)構(gòu)
▲ 作者：Julia V. Seidel, Bibiana Prinoth, Lorenzo Pino, Leonardo A. dos Santos, Hritam Chakraborty, Vivien Parmentier, et al.
▲鏈接：
https://www.nature.com/articles/s41586-025-08664-1
▲摘要：
超熱木星是一類極端系外行星，為研究大氣過(guò)程提供了獨(dú)特窗口。這類行星的晝/夜側(cè)存在極端的溫度差異，構(gòu)成了一個(gè)基本的氣候難題：能量是如何分布的？
為了解決這個(gè)問(wèn)題，研究組必須觀察這些大氣的三維結(jié)構(gòu)，尤其是其垂直環(huán)流模式，這些模式可作為先進(jìn)全球環(huán)流模型的試驗(yàn)臺(tái)。他們展示了超熱木星大氣環(huán)流的一個(gè)顯著變化：從行星朝向熾熱恒星一側(cè)到朝向較冷太空一側(cè)的緯向流動(dòng)位于赤道超旋轉(zhuǎn)急流下方。
通過(guò)解析大氣動(dòng)力學(xué)的垂直結(jié)構(gòu)，研究組不再局限于大氣的整體全球快照，能夠更準(zhǔn)確地識(shí)別流動(dòng)模式，并實(shí)現(xiàn)與模型進(jìn)行更細(xì)致的比較。基于第一性原理的全球環(huán)流模型難以復(fù)制觀測(cè)到的環(huán)流模式，這凸顯了對(duì)大氣流動(dòng)的理論理解與觀測(cè)證據(jù)之間存在的關(guān)鍵差距。
這項(xiàng)工作可作為一個(gè)試驗(yàn)臺(tái)，為下一代巨型望遠(yuǎn)鏡的投入使用做好準(zhǔn)備，以開(kāi)發(fā)適用于太陽(yáng)系之外天體的更全面模型。
▲ Abstract：
Ultra-hot Jupiters, an extreme class of planets not found in our Solar System, provide a unique window into atmospheric processes. The extreme temperature contrasts between their day and night sides pose a fundamental climate puzzle: how is energy distributed? To address this, we must observe the three-dimensional structure of these atmospheres, particularly their vertical circulation patterns that can serve as a testbed for advanced global circulation models, for example. Here we show a notable shift in atmospheric circulation in an ultra-hot Jupiter: a unilateral flow from the hot star-facing side to the cooler space-facing side of the planet sits below an equatorial super-rotational jet stream. By resolving the vertical structure of atmospheric dynamics, we move beyond integrated global snapshots of the atmosphere, enabling more accurate identification of flow patterns and allowing for a more nuanced comparison to models. Global circulation models based on first principles struggle to replicate the observed circulation pattern underscoring a critical gap between theoretical understanding of atmospheric flows and observational evidence. This work serves as a testbed to develop more comprehensive models applicable beyond our Solar System as we prepare for the next generation of giant telescopes.
物理學(xué)Physics
Hyperbolic phonon-polariton electroluminescence in 2D heterostructures
二維異質(zhì)結(jié)構(gòu)中的雙曲聲子-極化子電致發(fā)光
▲ 作者：Qiushi Guo, Iliya Esin, Cheng Li, Chen Chen, Guanyu Han, Song Liu, et al.
▲鏈接：
https://www.nature.com/articles/s41586-025-08686-9
▲摘要：
聲子極化子是極性電介質(zhì)中光子與光學(xué)聲子相干耦合產(chǎn)生的準(zhǔn)粒子。因其以低損耗將電場(chǎng)約束在深亞波長(zhǎng)尺度內(nèi)的特殊能力，聲子極化子具有獨(dú)特的優(yōu)勢(shì)，可以實(shí)現(xiàn)傳統(tǒng)光子學(xué)無(wú)法實(shí)現(xiàn)的一系列應(yīng)用，例如亞衍射成像和近場(chǎng)能量轉(zhuǎn)移。
然而，通過(guò)光學(xué)方法激發(fā)聲子極化子的傳統(tǒng)方法涉及昂貴的光源和近場(chǎng)方案，并且由于聲子極化子和自由空間光子之間的大量動(dòng)量失配，通常導(dǎo)致激發(fā)效率低。
研究組證明了在適當(dāng)?shù)臈l件下，聲子極化子可被非平衡態(tài)載流子全電激發(fā)。具體而言，在六方氮化硼（hBN）/石墨烯異質(zhì)結(jié)構(gòu)中，通過(guò)電驅(qū)動(dòng)超高遷移率石墨烯中的載流子脫離平衡，他們?cè)谥屑t外頻率下觀察到hBN的雙曲聲子極化子（HPhPs）的明亮電致發(fā)光，其表現(xiàn)出與黑體熱輻射不同的溫度和載流子密度依賴性。
此外，HPhP電致發(fā)光光譜的載流子密度依賴性表明，HPhP電致發(fā)光可以由石墨烯中電荷載流子的帶間躍遷和帶內(nèi)切倫科夫輻射引起。HPhP電致發(fā)光為實(shí)現(xiàn)電泵浦中紅外和太赫茲聲子極化子光源提供了途徑。
▲ Abstract：
Phonon polaritons are quasiparticles resulting from the coherent coupling of photons with optical phonons in polar dielectrics. Owing to their exceptional ability to confine electric fields to deep-subwavelength scales with low loss, they are uniquely poised to enable a suite of applications beyond the reach of conventional photonics, such as subdiffraction imaging and near-field energy transfer. The conventional approach to exciting phonon polaritons through optical methods, however, involves costly light sources along with near-field schemes, and generally leads to low excitation efficiency owing to substantial momentum mismatch between phonon polaritons and free-space photons. Here we demonstrate that under proper conditions, phonon polaritons can be excited all-electrically by drifting charge carriers. Specifically, in hexagonal boron nitride (hBN)/graphene heterostructures, by electrically driving charge carriers in ultrahigh-mobility graphene out of equilibrium, we observe bright electroluminescence of hBN’s hyperbolic phonon polaritons (HPhPs) at mid-infrared frequencies, which shows a temperature and carrier density dependence distinct from black-body thermal emission. Moreover, the carrier density dependence of the HPhP electroluminescence spectra reveals that HPhP electroluminescence can arise from both interband transition and intraband Cherenkov radiation of charge carriers in graphene. The HPhP electroluminescence offers avenues for realizing electrically pumped mid-infrared and terahertz phonon-polariton light sources.
Down-converted photon pairs in a high-Q silicon nitride microresonator
高Q氮化硅微諧振器中的下轉(zhuǎn)換光子對(duì)
▲ 作者：Bohan Li, Zhiquan Yuan, James Williams, Warren Jin, Adrian Beckert, Tian Xie, et al.
▲鏈接：
https://www.nature.com/articles/s41586-025-08662-3
▲摘要：
自發(fā)參量下轉(zhuǎn)換（SPDC）產(chǎn)生的糾纏光子對(duì)是許多量子應(yīng)用的核心。SPDC通常在具有固有二階非線性（χ(2)）的非中心對(duì)稱系統(tǒng)中進(jìn)行。
研究組在Si3N4中展示了具有每秒80萬(wàn)對(duì)片上速率的強(qiáng)窄帶SPDC。Si3N4是一種卓越的光子集成材料，并表現(xiàn)出最低的波導(dǎo)損耗（這對(duì)集成量子電路至關(guān)重要）。然而，由于氮化硅是無(wú)定形的，缺乏固有的χ(2)，這限制了其在光子量子器件中的作用。
研究組通過(guò)將高光學(xué)Q因子微腔內(nèi)的強(qiáng)光場(chǎng)增強(qiáng)與光誘導(dǎo)空間電荷場(chǎng)相結(jié)合，在Si3N4中實(shí)現(xiàn)了SPDC。他們提出了具有高光譜亮度的窄帶光子對(duì)。下轉(zhuǎn)換光子對(duì)的量子性質(zhì)通過(guò)符合測(cè)量驗(yàn)證。該光源基于Si3N4集成光子學(xué)技術(shù)，為片上量子系統(tǒng)開(kāi)辟了新途徑。
▲ Abstract：
Entangled photon pairs from spontaneous parametric down-conversion (SPDC) are central to many quantum applications. SPDC is typically performed in non-centrosymmetric systems with an inherent second-order nonlinearity (χ(2)). We demonstrate strong narrowband SPDC with an on-chip rate of 0.8 million pairs per second in Si3N4. Si3N4 is the pre-eminent material for photonic integration and also exhibits the lowest waveguide loss (which is essential for integrated quantum circuits). However, being amorphous, silicon nitride lacks an intrinsic χ(2), which limits its role in photonic quantum devices. We enabled SPDC in Si3N4 by combining strong light-field enhancement inside a high optical Q-factor microcavity with an optically induced space-charge field. We present narrowband photon pairs with a high spectral brightness. The quantum nature of the down-converted photon pairs is verified through coincidence measurements. This light source, based on Si3N4 integrated photonics technology, unlocks new avenues for quantum systems on a chip.
地球科學(xué)Earth Science
Record sea surface temperature jump in 2023–2024 unlikely but not unexpected
2023~2024年創(chuàng)紀(jì)錄的海表溫度躍升：不太可能，但并不意外
▲ 作者：Jens Terhaar, Friedrich A. Burger, Linus Vogt, Thomas L. Fr?licher & Thomas F. Stocker
▲鏈接：
https://www.nature.com/articles/s41586-025-08674-z
▲摘要：
從2023年4月開(kāi)始，全球海表溫度在一年多的時(shí)間里處于創(chuàng)紀(jì)錄水平，在2023年4月至2024年3月期間，平均比2015—2016年的記錄高出0.25℃。這一事件的范圍接近全球，強(qiáng)度前所未有，引發(fā)了人們的疑問(wèn)：它有多罕見(jiàn)？氣候模型是否能代表海表溫度如此破紀(jì)錄的躍升？
研究組構(gòu)建了基于觀測(cè)的合成時(shí)間序列，表明在當(dāng)前長(zhǎng)期變暖趨勢(shì)下，全球海表溫度的躍升至少打破了之前的記錄0.25℃，這是512年一遇的事件（205年一遇至1185年一遇；95%置信區(qū)間）。如果沒(méi)有全球變暖的趨勢(shì)，這樣的事件幾乎不可能發(fā)生。
通過(guò)對(duì)各種全耦合氣候模型進(jìn)行270次模擬，研究組發(fā)現(xiàn)這些模型成功模擬了全球海表溫度的破紀(jì)錄躍升，從而支持了這些模型在理解此類事件的特征、驅(qū)動(dòng)因素和后果方面的實(shí)用性。這些模型模擬表明，2023~2024年海表溫度破紀(jì)錄的躍升是一個(gè)極端事件，之后海表溫度預(yù)計(jì)將恢復(fù)到預(yù)期的長(zhǎng)期變暖趨勢(shì)。
▲ Abstract：
Global ocean surface temperatures were at record levels for more than a year from April 2023 onwards, exceeding the previous record in 2015–2016 by 0.25?°C on average between April 2023 and March 2024. The nearly global extent and unprecedented intensity of this event prompted questions about how exceptional it was and whether climate models can represent such record-shattering jumps in surface ocean temperatures. Here we construct observation-based synthetic time series to show that a jump in global sea surface temperatures that breaks the previous record by at least 0.25?°C is a 1-in-512-year event under the current long-term warming trend (1-in-205-year to 1-in-1,185-year event; 95% confidence interval). Without a global warming trend, such an event would have been practically impossible. Using 270 simulations from a wide range of fully coupled climate models, we show that these models successfully simulate such record-shattering jumps in global ocean surface temperatures, underpinning the models’ usefulness in understanding the characteristics, drivers and consequences of such events. These model simulations suggest that the record-shattering jump in surface ocean temperatures in 2023–2024 was an extreme event after which surface ocean temperatures are expected to revert to the expected long-term warming trend.
Sliding and healing of frictional interfaces that appear stationary
表觀靜止摩擦界面的滑動(dòng)和愈合
▲ 作者：Krittanon Sirorattanakul, Stacy Larochelle, Vito Rubino, Nadia Lapusta & Ares J. Rosakis
▲鏈接：
https://www.nature.com/articles/s41586-025-08673-0
▲摘要：
摩擦界面存在于從生物關(guān)節(jié)到地震斷層的各種系統(tǒng)中。這些界面何時(shí)以及如何滑動(dòng)是地球科學(xué)和工程中的一個(gè)基本問(wèn)題。人們認(rèn)為存在一個(gè)閾值剪切力，稱為靜摩擦力，低于該閾值界面是靜止的，盡管許多研究表明這一概念存在局限性。相比之下，速率和狀態(tài)摩擦公式雖然預(yù)測(cè)界面總是處于滑動(dòng)狀態(tài)，但這一特征通常被認(rèn)為是需要修正的理論假象。
研究組表明，受到恒定剪切和法向載荷的名義上靜止界面正在滑動(dòng)，其驅(qū)動(dòng)力明顯低于已知發(fā)生蠕變的經(jīng)典定義的靜摩擦，但速度越來(lái)越小，低至10-12ms-1。通過(guò)數(shù)字圖像相關(guān)性，研究組可以直接在界面上進(jìn)行精確測(cè)量。這種行為與經(jīng)典的摩擦模型相矛盾，但證實(shí)了速率和狀態(tài)摩擦的預(yù)測(cè)。
名義上靜止界面的滑動(dòng)率減小反映了界面的愈合，這將在隨后的滑動(dòng)事件（如地震和滑坡）中表現(xiàn)為更高的峰值摩擦，從而大大改變了其成核和傳播，進(jìn)而放大災(zāi)害規(guī)模。
▲ Abstract：
Frictional interfaces are found in systems ranging from biological joints to earthquake faults. When and how these interfaces slide is a fundamental problem in geosciences and engineering. It is believed that there exists a threshold shear force, called static friction, below which the interface is stationary, despite many studies suggesting that this concept is outdated. By contrast, rate-and-state friction formulations predict that interfaces are always sliding, but this feature is often considered an artefact that calls for modifications. Here we show that nominally stationary interfaces subjected to constant shear and normal loads, with a driving force that is notably below the classically defined static friction for which creep is known to occur, are sliding, but with diminishingly small rates down to 10-12 m s -1. Our precise measurements directly at the interface are enabled by digital image correlation. This behaviour contradicts classical models of friction but confirms the prediction of rate-and-state friction. The diminishing slip rates of nominally stationary interfaces reflect interface healing, which would manifest itself in higher peak friction in subsequent slip events, such as earthquakes and landslides, substantially modifying their nucleation and propagation and hence their hazard.
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