《自然》（20220804出版）一周论文导读

编译 | 冯维维

Nature, 4 AUG 2022, Volume 608，Issue 7921

《自然》2022年8月4日，第608卷，7921期

物理学Physics

Quantized current steps due to the a.c. coherent quantum phase-slip effect

由交流相干量子相滑移效应引起的量子化电流步长

▲ 作者：Rais S. Shaikhaidarov, Kyung Ho Kim, Jacob W. Dunstan, Ilya V. Antonov, Sven Linzen, Mario Ziegler, Dmitry S. Golubev, Vladimir N. Antonov, Evgeni V. Il’ichev & Oleg V. Astafiev

▲ 链接：

https://www.nature.com/articles/s41586-022-04947-z

▲ 摘要：

1962年预测并于1963年在实验中观测到的交流约瑟夫森效应是量子力学中最基本的现象之一，对计量量子电压标准至关重要。物理上的双重效应，交流相干量子相滑移（CQPS），通过超导纳米线的光子辅助磁通量隧穿，被设想为量子化的“电流步骤”。

在未来的现行标准中，交流电CQPS的基本物理意义也得到了实际重要性的补充，这是实现闭合量子计量三角的一个缺失元素。2012年，CQPS被证明是超导纳米线中磁通量量子的叠加。

然而，由于缺乏合适的材料和电路工程方面的挑战，超导的直流电平流步骤是迄今为止唯一无法实现的超导的基本效应。作者报告了在超导纳米线的双夏皮罗步骤的直接观察。

相关的步骤清晰到26 GHz频率，电流值8.3 nA，并受限于目前的设置带宽。目前的步骤是在30年前的小约瑟夫森连接理论上预测。

然而，约瑟夫森结不可避免的增宽阻碍了他们的直接实验观察。作者通过在感应环境中放置一个薄的NbN纳米线来解决这个问题。

▲ Abstract：

The a.c. Josephson effect predicted in 1962 and observed experimentally in 1963 as quantized ‘voltage steps’ (the Shapiro steps) from photon-assisted tunnelling of Cooper pairs is among the most fundamental phenomena of quantum mechanics and is vital for metrological quantum voltage standards. The physically dual effect, the a.c. coherent quantum phase slip (CQPS), photon-assisted tunnelling of magnetic fluxes through a superconducting nanowire, is envisaged to reveal itself as quantized ‘current steps. The basic physical significance of the a.c. CQPS is also complemented by practical importance in future current standards, a missing element for closing the quantum metrology triangle. In 2012, the CQPS was demonstrated as superposition of magnetic flux quanta in superconducting nanowires. However, the direct flat current steps in superconductors, the only unavailable basic effect of superconductivity to date, was unattainable due to lack of appropriate materials and challenges in circuit engineering. Here we report the direct observation of the dual Shapiro steps in a superconducting nanowire. The sharp steps are clear up to 26 GHz frequency with current values 8.3 nA and limited by the present set-up bandwidth. The current steps were theoretically predicted in small Josephson junctions 30 years ago. However, unavoidable broadening in Josephson junctions prevents their direct experimental observation. We solve this problem by placing a thin NbN nanowire in an inductive environment.

Non-Hermitian morphing of topological modes

拓扑模的非厄米变形

▲ 作者：Wei Wang, Xulong Wang & Guancong Ma

▲ 链接：

https://www.nature.com/articles/s41586-022-04929-1

▲ 摘要：

拓扑模态（TMs）通常局限于更大的拓扑晶格的缺陷或边界上。最近对非厄米能带理论的研究揭示了非厄米皮效应（NHSE），通过该效应，体态以皮模的形式向边界塌陷。作者探索了NHSE，以重塑波函数的TMs的非局域从边界。

在一个临界的非厄米参数下，间隙内TM甚至在整个体晶格中完全扩展，形成一个“连续体外的扩展模”。这些扩展模式仍然受到大频带拓扑的保护，使它们对局部混乱具有鲁棒性。实验实现了TM波函数在主动力学晶格中的变形，包括一维和二维拓扑晶格以及高阶拓扑晶格。

此外，通过明智地设计非厄米分布，TMs可以变形成各种形状。该发现不仅拓宽和深化了目前对TMs和NHSE的理解，而且为拓扑应用开辟了新的基础。

▲ Abstract：

Topological modes (TMs) are usually localized at defects or boundaries of a much larger topological lattice. Recent studies of non-Hermitian band theories unveiled the non-Hermitian skin effect (NHSE), by which the bulk states collapse to the boundary as skin modes. Here we explore the NHSE to reshape the wavefunctions of TMs by delocalizing them from the boundary. At a critical non-Hermitian parameter, the in-gap TMs even become completely extended in the entire bulk lattice, forming an ‘extended mode outside of a continuum’. These extended modes are still protected by bulk-band topology, making them robust against local disorders. The morphing of TM wavefunction is experimentally realized in active mechanical lattices in both one-dimensional and two-dimensional topological lattices, as well as in a higher-order topological lattice. Furthermore, by the judicious engineering of the non-Hermiticity distribution, the TMs can deform into a diversity of shapes. Our findings not only broaden and deepen the current understanding of the TMs and the NHSE but also open new grounds for topological applications.

化学Chemistry

Strong yet ductile nanolamellar high-entropy alloys by additive manufacturing

增材制造的强韧性纳米层状高熵合金

▲ 作者：Jie Ren, Yin Zhang, Dexin Zhao, Yan Chen, Shuai Guan, Yanfang Liu, Liang Liu, Siyuan Peng, Fanyue Kong, Jonathan D. Poplawsky, Guanhui Gao, Thomas Voisin, Ke An, Y. Morris Wang, Kelvin Y. Xie, Ting Zhu & Wen Chen

▲ 链接：

https://www.nature.com/articles/s41586-022-04914-8

▲ 摘要：

增材制造可一层一层地生产网状构件，用于工程应用。激光粉末床熔合（L-PBF）增材制造金属合金涉及大温度梯度和快速冷却，这使得纳米尺度的微结构细化达到高强度。

然而，激光增材制造的高强度纳米结构合金往往具有有限的延展性。作者使用L-PBF打印了合金材料AlCoCrFeNi2.1的双相纳米层状高熵合金（HEAs），该合金表现出约1.3吉帕的高屈服强度和约14%的大均匀伸长率，这超过了其他最先进的加法制造金属合金。

增材制造HEAs的变形行为的机理研究对具有特殊力学性能的分级、双相和多相纳米结构合金的发展具有广泛的影响。

▲ Abstract：

Additive manufacturing produces net-shaped components layer by layer for engineering applications. The additive manufacture of metal alloys by laser powder bed fusion (L-PBF) involves large temperature gradients and rapid cooling, which enables microstructural refinement at the nanoscale to achieve high strength. However, high-strength nanostructured alloys produced by laser additive manufacturing often have limited ductility. Here we use L-PBF to print dual-phase nanolamellar high-entropy alloys (HEAs) of AlCoCrFeNi2.1 that exhibit a combination of a high yield strength of about 1.3?gigapascals and a large uniform elongation of about 14?per cent, which surpasses those of other state-of-the-art additively manufactured metal alloys. The mechanistic insights into the deformation behaviour of additively manufactured HEAs have broad implications for the development of hierarchical, dual- and multi-phase, nanostructured alloys with exceptional mechanical properties.

Pulsed hydraulic-pressure-responsive self-cleaning membrane

脉冲液压响应式自洁膜

▲ 作者：Yang Zhao, Yuna Gu, Bin Liu, Yujie Yan, Chao Shan, Jian Guo, Shantao Zhang, Chad D. Vecitis & Guandao Gao

▲ 链接：

https://www.nature.com/articles/s41586-022-04942-4

▲ 摘要：

压力驱动膜是一种广泛应用于各种行业的分离技术，如水净化、生物加工、食品加工和化工生产。尽管它们有许多优点，如模块化设计和最小的占地面积，不可避免的膜污染是大多数实际应用的关键挑战。

污染通过降低渗透通量或增加压力要求来限制膜的性能，从而导致更高的能量运行和维护成本。作者报告了一种液压压力响应膜PiezoMem，将压力脉冲转化为现场自清洁的电活性响应。

膜上的瞬态液压波动会产生电流脉冲和快速电压振荡（峰值为+5.0/?3.2 V），能够降解和排斥污染物，而不需要补充的化学清洗剂、二次废物处理或进一步的外部刺激。

这种膜通过产生活性氧和介电排斥作用，对一系列膜污染物（包括有机分子、油滴、蛋白质、细菌和无机胶体）具有广谱防污作用。

▲ Abstract：

Pressure-driven membranes is a widely used separation technology in a range of industries, such as water purification, bioprocessing, food processing and chemical production. Despite their numerous advantages, such as modular design and minimal footprint, inevitable membrane fouling is the key challenge in most practical applications. Fouling limits membrane performance by reducing permeate flux or increasing pressure requirements, which results in higher energetic operation and maintenance costs Here we report a hydraulic-pressure-responsive membrane (PiezoMem) to transform pressure pulses into electroactive responses for in situ self-cleaning. A transient hydraulic pressure fluctuation across the membrane results in generation of current pulses and rapid voltage oscillations (peak, +5.0/3.2 V) capable of foulant degradation and repulsion without the need for supplementary chemical cleaning agents, secondary waste disposal or further external stimuli. PiezoMem showed broad-spectrum antifouling action towards a range of membrane foulants, including organic molecules, oil droplets, proteins, bacteria and inorganic colloids, through reactive oxygen species (ROS) production and dielectrophoretic repulsion.

Climate management & Volcanic geology

The challenge of unprecedented floods and droughts in risk management

气候管理和火山地质

前所未有的洪涝和干旱对风险管理的挑战

▲ 作者：Heidi Kreibich, Anne F. Van Loon, Giuliano Di Baldassarre

▲ 链接：

https://www.nature.com/articles/s41586-022-04917-5

▲ 摘要：

风险管理降低了全球范围内遭受洪水和干旱的脆弱性，但其影响仍在增加。因此，需要更好地了解影响变化的原因，但由于缺乏经验数据而受到阻碍。

根据在同一地区发生的45对事件的全球数据集，作者发现，风险管理通常会减少洪水和干旱的影响，但在减少以前从未经历过的前所未有的规模事件的影响方面面临困难。如果第二个事件比第一个事件危险得多，那么它的影响几乎总是更高。

这是因为管理并不是为了处理这种极端事件而设计的:例如，它们超过了堤坝和水库的设计水平。在两个成功的案例中，第二个更危险的事件的影响较低，这是改善风险管理治理和在综合管理方面投入大量资金的结果。

鉴于气候变化会带来更多的极端水文事件，研究认为管理前所未有事件的困难令人担忧。

▲ Abstract：

Risk management has reduced vulnerability to floods and droughts globally, yet their impacts are still increasing. An improved understanding of the causes of changing impacts is therefore needed, but has been hampered by a lack of empirical data. On the basis of a global dataset of 45?pairs of events that occurred within the same area, we show that risk management generally reduces the impacts of floods and droughts but faces difficulties in reducing the impacts of unprecedented events of a magnitude not previously experienced. If the second event was much more hazardous than the first, its impact was almost always higher. This is because management was not designed to deal with such extreme events: for example, they exceeded the design levels of levees and reservoirs. In two success stories, the impact of the second, more hazardous, event was lower, as a result of improved risk management governance and high investment in integrated management. The observed difficulty of managing unprecedented events is alarming, given that more extreme hydrological events are projected owing to climate change.

Timescales for pluton growth, magma-chamber formation and super-eruptions

岩体生长、岩浆房形成和超级喷发的时间尺度

▲ 作者：M. E. van Zalinge, D. F. Mark, R. S. J. Sparks, M. M. Tremblay, C. B. Keller, F. J. Cooper & A. Rust

▲ 链接：

https://www.nature.com/articles/s41586-022-04921-9

▲ 摘要：

硅质岩浆的生成导致花岗岩体的侵位、巨大的爆发性火山喷发以及大陆地壳和弧壳的物理化学分带。硅质岩浆在中地壳和深地壳的生成时间尺度延长，岩浆向上地壳迁移然后喷发可能是间歇性的，快速的。

安第斯地区中部4个中新世火成岩继承锆石和杂胺晶体的年龄表明，从岩体就位开始到超级火山爆发之间的时间间隔为460万年，具有1 百万年的旋回性。结果表明，继承性锆石和杂胺晶体在加入烧成岩岩浆之前，在这些岩体中保存温度<470℃。

我们的观测结果可以用中地壳热区的硅熔体分离来解释，热区顶部的不稳定层的熔体断断续续地上升，其时间尺度受上地壳流变学的控制。

生长中的岩体经过热孕育后，在几千年或更短的时间内，通过热区熔融层的岩脉运输，可以形成大型的上地壳岩浆房。早期深成岩的不稳定和破坏发生在超级火山爆发之前或期间的几十年或更短的时间内。

▲ Abstract：

Generation of silicic magmas leads to emplacement of granite plutons, huge explosive volcanic eruptions and physical and chemical zoning of continental and arc crust. Whereas timescales for silicic magma generation in the deep and middle crust are prolonged, magma transfer into the upper crust followed by eruption is episodic and can be rapid. Ages of inherited zircons and sanidines from four Miocene ignimbrites in the Central Andes indicate a gap of 4.6?Myr between initiation of pluton emplacement and onset of super-eruptions, with a 1-Myr cyclicity. We show that inherited zircons and sanidine crystals were stored at temperatures <470?°C in these plutons before incorporation in ignimbrite magmas. Our observations can be explained by silicic melt segregation in a middle-crustal hot zone with episodic melt ascent from an unstable layer at the top of the zone with a timescale governed by the rheology of the upper crust. After thermal incubation of growing plutons, large upper-crustal magma chambers can form in a few thousand years or less by dike transport from the hot-zone melt layer. Instability and disruption of earlier plutonic rock occurred in a few decades or less just before or during super-eruptions.