《自然》（20211104出版）一周論文導讀

編譯 | 李言

nature, 4 november 2021, volume 599 issue 7883

《自然》2021年11月4日，第599卷，7883期

材料科學material science

reconstruction of bloch wavefunctions of holes in a semiconductor

半導體空穴中布洛赫波函數的重建

▲ 作者：j. b. costello, s. d. o’hara, q. wu, d. c. valovcin, l. n. pfeiffer, k. w. west & m. s. sherwin

▲ 連結：

https://www.nature.com/articles/s41586-021-03940-2

▲ 摘要

在高階邊帶産生中，近紅外雷射在半導體中産生的電子和空穴被強太赫茲場加速到高動能，并在散射前反沖發射近紅外邊帶。

在此，我們通過實驗測量邊帶極化，并引入一個理論，将這些極化與不同的回憶路徑之間的量子幹涉聯系起來，重建了砷化镓中兩種類型的空穴在波長遠長于原子間距的波長下的布洛赫波函數。這些布洛赫波函數在球體的表面上緊密可見。 原則上，任何直接間隙半導體或絕緣體都可以觀察到高階邊帶産生。

是以，我們期望這裡介紹的方法可以用于重建這些材料中的低能量布洛赫波函數，進而對凝聚态物質的電子和光學性質的起源和工程有重要的見解。

▲ abstract

in high-order sideband generation, electrons and holes generated in semiconductors by a near-infrared laser are accelerated to a high kinetic energy by a strong terahertz field, and recollide to emit near-infrared sidebands before they are scattered. here we reconstruct the bloch wavefunctions of two types of hole in gallium arsenide at wavelengths much longer than the spacing between atoms by experimentally measuring sideband polarizations and introducing an elegant theory that ties those polarizations to quantum interference between different recollision pathways. these bloch wavefunctions are compactly visualized on the surface of a sphere. high-order sideband generation can, in principle, be observed from any direct-gap semiconductor or insulator. we thus expect that the method introduced here can be used to reconstruct low-energy bloch wavefunctions in many of these materials, enabling important insights into the origin and engineering of the electronic and optical properties of condensed matter.

percolation transitions in compressed sio2 glasses

壓縮二氧化矽玻璃中的滲透轉變

▲ 作者：a. hasmy, s. ispas & b. hehlen

https://www.nature.com/articles/s41586-021-03918-0

在此，我們報告了壓縮二氧化矽玻璃的從頭計算，表明結構變化從低到高密度的非晶結構發生了一系列的滲透躍遷。

當壓力增加到82 gpa時，在臨界壓力下，一系列由角或邊共享的四面體、五面體和最終八面體組成的長程（“無限”）滲流團簇出現，取代了之前的低折疊協調多面體和低連通性的“階段”。這一機制為衆所周知的3 gpa左右的機械異常以及超過10 gpa的結構不可逆性等特征提供了一個自然的解釋。

一些已經發現的非晶結構與最近報道的科石晶iv和v晶體相似，突出了sio5五面體基多晶在玻璃狀二氧化矽緻密化過程中的主要作用。我們的研究結果表明，滲流理論為了解非晶-非晶相變的性質和途徑提供了一個堅實的架構，并為預測解開的非晶固态和相關液相開辟了新的途徑。

here we report ab initio-based calculations of compressed silica (sio2) glasses, showing that the structural changes from low- to high-density amorphous structures occur through a sequence of percolation transitions. when the pressure is increased to 82 gpa, a series of long-range (‘infinite’) percolating clusters composed of corner- or edge-shared tetrahedra, pentahedra and eventually octahedra emerge at critical pressures and replace the previous ‘phase’ of lower-fold coordinated polyhedra and lower connectivity. this mechanism provides a natural explanation for the well-known mechanical anomaly around 3 gpa, as well as the structural irreversibility beyond 10 gpa, among other features. some of the amorphous structures that have been discovered mimic those of coesite iv and v crystals reported recently, highlighting the major role of sio5 pentahedron-based polyamorphs in the densification process of vitreous silica. our results demonstrate that percolation theory provides a robust framework to understand the nature and pathway of amorphous–amorphous transformations and open a new avenue to predict unravelled amorphous solid states and related liquid phases.

transition metal-catalysed molecular n-doping of organic semiconductors

過渡金屬催化有機半導體分子n-型摻雜

▲ 作者：han guo, chi-yuan yang, xianhe zhang, alessandro motta, kui feng, yu xia, yongqiang shi, ziang wu, kun yang, jianhua chen, qiaogan liao, yumin tang, huiliang sun, han young woo, simone fabiano, antonio facchetti & xugang guo

https://www.nature.com/articles/s41586-021-03942-0

在此，我們展示了使用空氣穩定前驅體型分子摻雜的有機半導體催化n-型摻雜的一般概念。

通過實驗和理論證據評估，過渡金屬（例如，pt, au, pd）作為氣相沉積的納米顆粒或溶液可處理的有機金屬配合物（例如，pd2(dba)3）的摻入催化反應， 在較短的摻雜時間内，η值顯著提高，電導率高（大于100 s cm−1; ref）。

該方法對實作改進的半導體器件具有技術意義，并為催化劑、分子摻雜劑和半導體三元體系提供了廣闊的探索空間，進而為n-型摻雜的研究和應用開辟了新的機遇。

here we show a general concept of catalysed n-doping of organic semiconductors using air-stable precursor-type molecular dopants. incorporation of a transition metal (for example, pt, au, pd) as vapour-deposited nanoparticles or solution-processable organometallic complexes (for example, pd2(dba)3) catalyses the reaction, as assessed by experimental and theoretical evidence, enabling greatly increased η in a much shorter doping time and high electrical conductivities (above 100 s cm−1; ref.). this methodology has technological implications for realizing improved semiconductor devices and offers a broad exploration space of ternary systems comprising catalysts, molecular dopants and semiconductors, thus opening new opportunities in n-doping research and applications.

資訊技術information technology

experimental relativistic zero-knowledge proofs

實驗相對論零知識證明

▲ 作者：pouriya alikhani, nicolas brunner, claude crépeau, sébastien designolle, raphaël houlmann, weixu shi, nan yang & hugo zbinden

https://www.nature.com/articles/s41586-021-03998-y

在當今資訊化時代，保密是一項重大挑戰。計算機科學的發展通過零知識證明的概念提供了一個優雅的解決方案：證明者可以說服驗證者某一陳述的有效性，而根本不需要對證明進行詳細闡述。

在這項研究中，我們報告了這種零知識協定的實驗實作，涉及兩個分離的驗證者-驗證者對。安全性是通過狹義相對論的實體原理來實施的，不需要計算假設（例如單向函數的存在）。

我們的實施完全依賴于現成的裝置，無論長（≥400米）或短（60米）距離都在1秒内起效。這證明了多驗證者零知識協定的實際潛力，在身份識别任務和區塊鍊應用（如加密貨币或智能合約）方面很有前景。

protecting secrets is a key challenge in our contemporary information-based era. developments in computer science provide an elegant solution via the concept of zero-knowledge proofs: a prover can convince a verifier of the validity of a certain statement without facilitating the elaboration of a proof at all. in this work, we report the experimental realization of such a zero-knowledge protocol involving two separated verifier–prover pairs. security is enforced via the physical principle of special relativity, and no computational assumption (such as the existence of one-way functions) is required. our implementation exclusively relies on off-the-shelf equipment and works at both short (60 m) and long distances (≥400 m) in about one second. this demonstrates the practical potential of multi-prover zero-knowledge protocols, promising for identification tasks and blockchain applications such as cryptocurrencies or smart contracts.

地球科學geoscience

episodic deluges in simulated hothouse climates

模拟溫室氣候中的偶發洪水

▲ 作者：jacob t. seeley & robin d. wordsworth

https://www.nature.com/articles/s41586-021-03919-z

以前的工作表明，這可能導緻溫度逆溫和雲層覆寫的重大變化，但之前的溫室制度模型沒有直接解決對流尺度的湍流空氣運動和雲層覆寫，是以留下了許多溫室輻射加熱的問題沒有答案。

在此，我們的模拟明确解決了對流問題，并發現溫室氣候中的低對流層輻射加熱導緻水文循環從準穩定狀态轉變為“松弛振蕩”狀态——在這種狀态下，發生在短而強烈的降水，間隔着多天的幹旱期。

向振蕩狀态的轉變伴随着當地降水通量的強烈增強，雲層覆寫的大量增加，以及一個短暫的正向（不穩定）氣候回報參數。我們的研究結果表明，溫室氣候可能具有一種“暫時”對流自組織的新形式，并對雲層覆寫和侵蝕過程都有影響。

previous work has suggested that this could lead to temperature inversions and substantial changes in cloud cover, but no previous modelling of the hothouse regime has resolved convective-scale turbulent air motions and cloud cover directly, thus leaving many questions about hothouse radiative heating unanswered. here we conduct simulations that explicitly resolve convection and find that lower-tropospheric radiative heating in hothouse climates causes the hydrologic cycle to shift from a quasi-steady regime to a ‘relaxation oscillator’ regime, in which precipitation occurs in short and intense outbursts separated by multi-day dry spells. the transition to the oscillatory regime is accompanied by strongly enhanced local precipitation fluxes, a substantial increase in cloud cover, and a transiently positive (unstable) climate feedback parameter. our results indicate that hothouse climates may feature a novel form of ‘temporal’ convective self-organization, with implications for both cloud coverage and erosion processes.

經濟學economics

carbon implications of marginal oils from market-derived demand shocks

來自市場需求沖擊的邊際石油對碳的影響

▲ 作者：mohammad s. masnadi, giacomo benini, hassan m. el-houjeiri, alice milivinti, james e. anderson, timothy j. wallington, robert de kleine, valerio dotti, patrick jochem & adam r. brandt

https://www.nature.com/articles/s41586-021-03932-2

我們探讨了邊際原油來源的生命周期溫室氣體排放影響，确定了對石油需求下降（例如，由于轉向替代汽車）最敏感的生産者的上遊碳強度（ci）。

我們将1933個油田（約占2015年全球供應量的90%）的生産盈利能力計量模型與它們的生産ci聯系起來。然後，我們在3種石油市場結構下考察它們對需求下降的反應。

據我們估算，小的需求沖擊與大的沖擊具有不同的上遊ci影響。不管市場結構如何，小沖擊（需求−2.5%）取代的主要是重質原油，其ci比全球平均水準高出25-54%。

然而，當沖擊變得更大時，如果具有市場力量的生産者協調應對需求下降，這種不平衡就會減弱。減少石油需求的碳排放效益系統地取決于需求下降的幅度和全球石油市場結構。

we explore the life-cycle greenhouse gas emissions impacts of marginal crude sources, identifying the upstream carbon intensity (ci) of the producers most sensitive to an oil demand decline (for example, due to a shift to alternative vehicles). we link econometric models of production profitability of 1,933 oilfields (~90% of the 2015 world supply) with their production ci. then, we examine their response to a decline in demand under three oil market structures. according to our estimates, small demand shocks have different upstream ci implications than large shocks. irrespective of the market structure, small shocks (−2.5% demand) displace mostly heavy crudes with ~25–54% higher ci than that of the global average. however, this imbalance diminishes as the shocks become bigger and if producers with market power coordinate their response to a demand decline. the carbon emissions benefits of reduction in oil demand are systematically dependent on the magnitude of demand drop and the global oil market structure.