《科學》（20200918出版）一周論文導讀

編譯 | 李言

Science, 18 SEPTEMBER 2020, VOL 369, ISSUE 6510

《科學》2020年9月18日，第369卷，6510期

物理Physics

Reversible structural transformations in supercooled liquid water from 135 to 245 K

在135K到245K的過冷水中的可逆結構轉變

▲ 作者：Loni Kringle, Wyatt A. Thornley, Bruce D. Kay, Greg A. Kimmel

▲ 連結：

https://science.sciencemag.org/content/369/6510/1490

▲ 摘要

對水不同尋常的特性的基本理解仍然是難以捉摸的，因為在不同理論中做出決定所需要的溫度和壓力的數據有限。

我們研究了瞬時加熱過冷水膜的結構轉變，在快速雷射加熱到70K之前，每脈衝演變數納秒。在明顯的結晶之前，水的結構從最初的形態放鬆到穩定的形態。

在研究的全部溫度範圍內，所有的結構變化是可逆的和可重複的線性組合的高溫和低溫結構。隨著溫度從245K降至190K，高溫組分液體的比例迅速下降，這與超臨界狀態下過冷水的雙態「混合物」模型的預測一致。

▲ Abstract

A fundamental understanding of the unusual properties of water remains elusive because of the limited data at the temperatures and pressures needed to decide among competing theories. We investigated the structural transformations of transiently heated supercooled water films, which evolved for several nanoseconds per pulse during fast laser heating before quenching to 70 kelvin (K). Water’s structure relaxed from its initial configuration to a steady-state configuration before appreciable crystallization. Over the full temperature range investigated, all structural changes were reversible and reproducible by a linear combination of high- and low-temperature structural motifs. The fraction of the liquid with the high-temperature motif decreased rapidly as the temperature decreased from 245 to 190 K, consistent with the predictions of two-state 「mixture」 models for supercooled water in the supercritical regime.

Universal coherence protection in a solid-state spin qubit

固態自旋量子比特中的通用相干保護

▲ 作者：Kevin C. Miao, Joseph P. Blanton, Christopher P. Anderson, Alexandre Bourassa, et al

▲ 連結：

https://science.sciencemag.org/content/369/6510/1493

▲ 摘要

退相干限制了量子比特的物理實現，而退相干的緩解對量子科學技術的發展至關重要。通過對碳化矽缺陷基態電子自旋的時鐘躍遷進行微波修飾，構造了一個嵌入到退相干保護子空間中的魯棒量子比特。

量子比特被通用保護，不受磁、電和溫度波動的影響，這些因素幾乎佔了固態中所有相關的退相干通道。這使得量子位元的非均勻去相時間增加了4個數量級（>為22毫秒），而它的哈恩回波相干時間接近64毫秒。

這一結果表明，在廣泛選擇的量子架構中可以實現實質性的一致性改進，僅需很少的關鍵平臺獨立組件。

▲ Abstract

Decoherence limits the physical realization of qubits, and its mitigation is critical for the development of quantum science and technology. We construct a robust qubit embedded in a decoherence-protected subspace, obtained by applying microwave dressing to a clock transition of the ground-state electron spin of a silicon carbide divacancy defect. The qubit is universally protected from magnetic, electric, and temperature fluctuations, which account for nearly all relevant decoherence channels in the solid state. This culminates in an increase of the qubit’s inhomogeneous dephasing time by more than four orders of magnitude (to >22 milliseconds), while its Hahn-echo coherence time approaches 64 milliseconds. Requiring few key platform-independent components, this result suggests that substantial coherence improvements can be achieved in a wide selection of quantum architectures.

化學Chemistry

Following the microscopic pathway to adsorption through chemisorption and physisorption wells

通過化學吸附井和物理吸附井進行微觀吸附

▲ 作者：Dmitriy Borodin, Igor Rahinov, Pranav R. Shirhatti, Meng Huang, Alexander Kandratsenka, et al.

▲ 連結：

https://science.sciencemag.org/content/369/6510/1461

▲ 摘要

吸附涉及分子在固體表面的碰撞，並通過一個動態的途徑能達到平衡以失去入射能。造成能量損失的相互作用一般包括化學鍵的形成（化學吸附）和非鍵的相互作用（物理吸附）。

在這項研究中，我們的實驗揭示了一個定量的能量景觀和一個分子與原型系統表面平衡的微觀途徑：CO吸附在Au（111）上。雖然最小能態是物理控制的，但氣體相分子的初始捕獲，加上高能分子束，會進入亞穩化學吸附狀態。

化學吸附態的隨後熱衰變使分子達到物理吸附的最小值。通過精準平衡，我們發現熱吸附到兩種結合狀態在所有溫度下都很重要。

▲ Abstract

Adsorption involves molecules colliding at the surface of a solid and losing their incidence energy by traversing a dynamical pathway to equilibrium. The interactions responsible for energy loss generally include both chemical bond formation (chemisorption) and nonbonding interactions (physisorption). In this work, we present experiments that revealed a quantitative energy landscape and the microscopic pathways underlying a molecule’s equilibration with a surface in a prototypical system: CO adsorption on Au(111). Although the minimum energy state was physisorbed, initial capture of the gas-phase molecule, dosed with an energetic molecular beam, was into a metastable chemisorption state. Subsequent thermal decay of the chemisorbed state led molecules to the physisorption minimum. We found, through detailed balance, that thermal adsorption into both binding states was important at all temperatures.

天文學Astronomy

(Sub)stellar companions shape the winds of evolved stars

次恆星伴星塑造演化恆星的星風

▲ 作者：L. Decin, M. Montargès, A. M. S. Richards, C. A. Gottlieb, W. Homan, I. McDonald, I. El Mellah, et al.

▲ 連結：

https://science.sciencemag.org/content/369/6510/1497

▲ 摘要

雙星相互作用主導了大質量恆星的演化，但它們在低質量和中質量恆星中的作用不太明確。球形風從漸進巨星支（AGB）恆星演化為非球形行星狀星雲（PN）可能是由於雙星相互作用。

我們用阿塔卡瑪大型毫米波天線陣（ALMA）觀察了AGB恆星的樣本，發現它們的星風呈現出獨特的非球面幾何形狀，與行星狀星雲（PNe）的形態相似。我們推斷，形成AGB星風和PNe星風的物理過程是相同的；此外，地形與AGB的質量損失率也有相關性。

這些特徵可以用二元相互作用來解釋。我們提出了一個與AGB星和PNe中觀察到的現象一致的AGB形態的演化方案。

▲ Abstract

Binary interactions dominate the evolution of massive stars, but their role is less clear for low- and intermediate-mass stars. The evolution of a spherical wind from an asymptotic giant branch (AGB) star into a nonspherical planetary nebula (PN) could be due to binary interactions. We observed a sample of AGB stars with the Atacama Large Millimeter/submillimeter Array (ALMA) and found that their winds exhibit distinct nonspherical geometries with morphological similarities to planetary nebulae (PNe). We infer that the same physics shapes both AGB winds and PNe; additionally, the morphology and AGB mass-loss rate are correlated. These characteristics can be explained by binary interaction. We propose an evolutionary scenario for AGB morphologies that is consistent with observed phenomena in AGB stars and PNe.

地球科學Geoscience

Seismic ocean thermometry

地震海洋測溫

▲ 作者：Wenbo Wu, Zhongwen Zhan, Shirui Peng, Sidao Ni, Jörn Callies

▲ 連結：

https://science.sciencemag.org/content/369/6510/1510

▲ 摘要

地球上日益豐富的溫室氣體所捕獲的能量中，有90%以上被海洋吸收。監測由此導致的海洋變暖仍然是一個具有挑戰性的採樣問題。

為了補充現有的點測量，我們引入了一種方法，從重複地震產生的聲波的傳播時間來推斷盆級深海溫度變化。這種海洋地震測溫技術的首次應用，以0.0060 K的標準誤差，限制了赤道東印度洋一段3000公裡長的區域的平均溫度異常。

從2005年到2016年，我們發現溫度在12個月、6個月和10天左右的時間尺度上有波動，我們推斷出一個明顯超過之前估計的10年變暖趨勢。

▲ Abstract

More than 90% of the energy trapped on Earth by increasingly abundant greenhouse gases is absorbed by the ocean. Monitoring the resulting ocean warming remains a challenging sampling problem. To complement existing point measurements, we introduce a method that infers basin-scale deep-ocean temperature changes from the travel times of sound waves that are generated by repeating earthquakes. A first implementation of this seismic ocean thermometry constrains temperature anomalies averaged across a 3000-kilometer-long section in the equatorial East Indian Ocean with a standard error of 0.0060 kelvin. Between 2005 and 2016, we find temperature fluctuations on time scales of 12 months, 6 months, and ~10 days, and we infer a decadal warming trend that substantially exceeds previous estimates.

環境科學Environmental Sciences

Evaluating scenarios toward zero plastic pollution

評估實現塑料零汙染的方案

▲ 作者：Winnie W. Y. Lau, Yonathan Shiran, Richard M. Bailey, Ed Cook, Martin R. Stuchtey, et al.

▲ 連結

https://science.sciencemag.org/content/369/6510/1455

▲ 摘要

塑料汙染是一個日益嚴重的普遍問題。為了評估減少塑料汙染幹預措施的有效性，我們對2016年至2040年期間全球塑料系統中城市固體廢物和四種微塑料來源的存量和流動進行了建模。

通過實施所有可行的幹預措施，塑料汙染比2016年減少了40%，與2040年相比減少了78%。即使採取立即和協調一致的行動，仍有7.1億公噸的塑料廢物累積進入水生和陸地生態系統。

為了避免塑料在環境中大量堆積，迫切需要採取協調一致的全球行動來減少塑料的消耗；提高廢物再利用、收集和循環再造率；擴大安全處置系統；以及加快塑料價值鏈創新。

▲ Abstract

Plastic pollution is a pervasive and growing problem. To estimate the effectiveness of interventions to reduce plastic pollution, we modeled stocks and flows of municipal solid waste and four sources of microplastics through the global plastic system for five scenarios between 2016 and 2040. Implementing all feasible interventions reduced plastic pollution by 40% from 2016 rates and 78% relative to 「business as usual」 in 2040. Even with immediate and concerted action, 710 million metric tons of plastic waste cumulatively entered aquatic and terrestrial ecosystems. To avoid a massive build-up of plastic in the environment, coordinated global action is urgently needed to reduce plastic consumption; increase rates of reuse, waste collection, and recycling; expand safe disposal systems; and accelerate innovation in the plastic value chain.

Predicted growth in plastic waste exceeds efforts to mitigate plastic pollution

預計中的塑料垃圾增長超出減少塑料汙染的努力

▲ 作者：Stephanie B. Borrelle, Jeremy Ringma, Kara Lavender Law, Cole C. Monnahan, Laurent Lebreton, et al.

▲ 連結：

https://science.sciencemag.org/content/369/6510/1515

▲ 摘要

塑料汙染是一個全球性的威脅，幾乎影響著全球每一個海洋和淡水生態系統。為此，正在採取多級緩解戰略，但缺乏對這些戰略如何減少塑料排放的定量評估。

我們評估了減少塑料廢物、廢物管理和環境恢復這三種總體管理策略在不同努力水平上的影響，以估計173個國家到2030年的塑料排放量。我們估計，2016年全球產生的塑料垃圾中有1900萬至2300萬噸（11%）進入了水生生態系統。

考慮到各國政府目前作出的承諾，到2030年，年排放量可能達到每年5300萬公噸。要把排放量降低到遠低於這一預測的水平，就需要做出非凡的努力來改變全球塑料經濟。

▲ Abstract

Plastic pollution is a planetary threat, affecting nearly every marine and freshwater ecosystem globally. In response, multilevel mitigation strategies are being adopted but with a lack of quantitative assessment of how such strategies reduce plastic emissions. We assessed the impact of three broad management strategies, plastic waste reduction, waste management, and environmental recovery, at different levels of effort to estimate plastic emissions to 2030 for 173 countries. We estimate that 19 to 23 million metric tons, or 11%, of plastic waste generated globally in 2016 entered aquatic ecosystems. Considering the ambitious commitments currently set by governments, annual emissions may reach up to 53 million metric tons per year by 2030. To reduce emissions to a level well below this prediction, extraordinary efforts to transform the global plastics economy are needed.