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发布日期：2024-09-03 作者：开博
Science, 21 JUN 2024, VOL 384, ISSUE 6702
《科学》2024年6月21日，第384卷，6702期
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物理学Physics
Topological Hong-Ou-Mandel interference
拓扑Hong-Ou-Mandel干与
▲ 作者：MAX EHRHARDT, CHRISTOPH DITTEL, MATTHIAS HEINRICH AND ALEXANDER SZAMEIT
▲ 链接：
https://www.science.org/doi/10.1126/science.ado8192
▲ 摘要：
拓扑学和光学的彼此感化为寻求稳健的光子器件供给了一条路子，其在光子量子计较中的利用尚处在起步阶段。但是，经由过程光子的量子干与，操纵线性光学拓扑布局处置量子信息的可能性在很年夜水平上依然未知。
研究组提出了一种拓扑发源的Hong-Ou-Mandel干与效应。成果注解，光子对的这类从相长到相消的干与完全由合成磁通量决议，使其在根基程度上对误差具有弹性。
该策略成立了一个量子化通量，仅增进相消量子干与。该发现为受拓扑稳健量子门庇护的下一代光子量子电路和可扩大量子计较的成长摊平了道路。
▲ Abstract：
The interplay of topology and optics provides a route to pursue robust photonic devices, with the application to photonic quantum computation in its infancy. However, the possibilities of harnessing topological structures to process quantum information with linear optics, through the quantum interference of photons, remain largely uncharted. Here, we present a Hong-Ou-Mandel interference effect of topological origin. We show that this interference of photon pairs—ranging from constructive to destructive—is solely determined by a synthetic magnetic flux, rendering it resilient to errors on a fundamental level. Our implementation establishes a quantized flux that facilitates exclusively destructive quantum interference. Our findings pave the way toward the development of next-generation photonic quantum circuitry and scalable quantum computing protected by virtue of topologically robust quantum gates.
材料科学Materials Science
Carbon nanotube fibers with dynamic strength up to 14 GPa
动态强度高达14 GPa的碳纳米管纤维
▲ 作者：XINSHI ZHANG, XUDONG LEI, XIANGZHENG JIA, TONGZHAO SUN, JIAJUN LUO, SHICHEN XU, ET AL.
▲ 链接：
https://www.science.org/doi/10.1126/science.adj1082
▲ 摘要：
高动态强度对在高应变率情况中利用的纤维材料相当主要。碳纳米管纤维是最有前景的候选纤维之一。
采取优化分层布局的策略，研究组制备出动态强度为14 GPa且能量接收机能优良的碳纳米管纤维。纤维的动态机能归因在高应变率加载进程中单个纳米管的同时断裂和冲击能量的离域；这些行动则归因在界面彼此感化、纳米管摆列和致密化的改良。
这项工作提出了一种在宏不雅标准上操纵单个碳纳米管强度的有用策略，并供给了新的机制看法。
▲ Abstract：
High dynamic strength is of fundamental importance for fibrous materials that are used in high–strain rate environments. Carbon nanotube fibers are one of the most promising candidates. Using a strategy to optimize hierarchical structures, we fabricated carbon nanotube fibers with a dynamic strength of 14 gigapascals (GPa) and excellent energy absorption. The dynamic performance of the fibers is attributed to the simultaneous breakage of individual nanotubes and delocalization of impact energy that occurs during the high–strain rate loading process; these behaviors are due to improvements in interfacial interactions, nanotube alignment, and densification therein. This work presents an effective strategy to utilize the strength of individual carbon nanotubes at the macroscale and provides fresh mechanism insights.
Spin torque–driven electron paramagnetic resonance of a single spin in a pentacene molecule
并五苯份子中单个自旋的自旋力矩驱动的电子顺磁共振
▲ 作者：STEPAN KOVARIK, RICHARD SCHLITZ, AISHWARYA VISHWAKARMA, DOMINIC RUCKERT, PIETRO GAMBARDELLA AND SEBASTIAN STEPANOW
▲ 链接：
https://www.science.org/doi/10.1126/science.adh4753
▲ 摘要：
对量子系统的调控凡是由与时候相干的电场或磁场来实现。别的，电子自旋可经由过程自旋极化电流来节制。
研究组演示了从扫描地道显微镜尖端注入射频自旋极化电流至有机份子中的单个自旋相关驱动。在电子顺磁共振激起下，操纵局域电畅通过自旋力矩成立了单个自旋的动态节制。
另外，该工作强调了自扭转移力矩的耗散感化，这与基在受控退相关把持单个自旋的磁场非耗散感化迥然分歧。
▲ Abstract：
Control over quantum systems is typically achieved by time-dependent electric or magnetic fields. Alternatively, electronic spins can be controlled by spin-polarized currents. Here, we demonstrate coherent driving of a single spin by a radiofrequency spin-polarized current injected from the tip of a scanning tunneling microscope into an organic molecule. With the excitation of electron paramagnetic resonance, we established dynamic control of single spins by spin torque using a local electric current. In addition, our work highlights the dissipative action of the spin-transfer torque, in contrast to the nondissipative action of the magnetic field, which allows for the manipulation of individual spins based on controlled decoherence.
化学Chemistry
Water-hydroxide trapping in cobalt tungstate for proton exchange membrane water electrolysis
钨酸钴中水-氢氧化物收集捕捉助力质子互换膜水电解
▲ 作者：RANIT RAM, LU XIA, HIND BENZIDI, ANKU GUHA, VIKTORIA GOLOVANOVA, ALBA GARZóN MANJóN, ET AL.
▲ 链接：
https://www.science.org/doi/10.1126/science.adk9849
▲ 摘要：
析氧反映是高能效水基电解出产氢气和其他太阳能燃料的瓶颈。在质子互换膜水电解（PEMWE）中，贵金属凡是是不变催化该反映所必须的。
在这项工作中，研究组报导了钨酸钴的分层经由过程不变酸中晶格缺点的氧化物和水—氢氧化物收集，实现了高活性和经久性。所获得的催化剂具有较低的过电位，2 V下的电流密度为1.8 A/cm2，1.77 V的工业前提下（80℃）在PEMWE系统中不变运行时可高达1 A/cm2；活性提高了三倍；在1 A/cm2的电流密度下可不变运行600小时。
▲ Abstract：
The oxygen evolution reaction is the bottleneck to energy-efficient water-based electrolysis for the production of hydrogen and other solar fuels. In proton exchange membrane water electrolysis (PEMWE), precious metals have generally been necessary for the stable catalysis of this reaction. In this work, we report that delamination of cobalt tungstate enables high activity and durability through the stabilization of oxide and water-hydroxide networks of the lattice defects in acid. The resulting catalysts achieve lower overpotentials, a current density of 1.8 amperes per square centimeter at 2 volts, and stable operation up to 1 ampere per square centimeter in a PEMWE system at industrial conditions (80°C) at 1.77 volts; a threefold improvement in activity; and stable operation at 1 ampere per square centimeter over the course of 600 hours.
地球科学Earth Science
Temperature-dependent emissions dominate aerosol and ozone formation in Los Angeles
温度依靠的排放主导着洛杉矶气溶胶和臭氧构成
▲ 作者：EVA Y. PFANNERSTILL, CALEB ARATA, QINDAN ZHU, BENJAMIN C. SCHULZE, RYAN WARD, ROY WOODS, ET AL.
▲ 链接：
https://www.science.org/doi/10.1126/science.adg8204
▲ 摘要：
虽然交通排放量有所降落，但北美和欧洲城市仍面对着不健康的空气污染程度。这挑战了对其挥发性有机化合物（VOC）前体来历的传统理解。
利用空气通量丈量来绘制年夜规模VOC的排放图，研究组注解，生物萜类排放约占夏日洛杉矶排放的VOC OH反映活性、臭氧和二次有机气溶胶构成潜力的60%，而且该影响跟着温度的升高而强烈增添。这意味着节制氮氧化物是削减洛杉矶臭氧构成的要害。
研究组还注解，一些报酬VOC排放量跟着温度升高而增添，这是当前减排清单中未表现的变数。减缓空气污染的尽力必需斟酌到天气变暖将强烈改变排放量和排放成份。
▲ Abstract：
Despite declines in transportation emissions, urban North America and Europe still face unhealthy air pollution levels. This has challenged conventional understanding of the sources of their volatile organic compound (VOC) precursors. Using airborne flux measurements to map emissions of a wide range of VOCs, we demonstrate that biogenic terpenoid emissions contribute ~60% of emitted VOC OH reactivity, ozone, and secondary organic aerosol formation potential in summertime Los Angeles and that this contribution strongly increases with temperature. This implies that control of nitrogen oxides is key to reducing ozone formation in Los Angeles. We also show some anthropogenic VOC emissions increase with temperature, which is an effect not represented in current inventories. Air pollution mitigation efforts must consider that climate warming will strongly change emission amounts and composition.
Bomb radiocarbon evidence for strong global carbon uptake and turnover in terrestrial vegetation
全球陆地植被壮大碳接收和周转量的核弹放射性碳证据
▲ 作者：HEATHER D. GRAVEN, HAMISH WARREN, HOLLY K. GIBBS, S开博体育AMAR KHATIWALA, CHARLES KOVEN, JOANNA LESTER, ET AL.
▲ 链接：
https://www.science.org/doi/10.1126/science.adl4443
▲ 摘要：
因为出产力和周转量发生的年夜量总碳互换存在束缚很差的细小不服衡，植被和泥土接收了年夜约30%的报酬二氧化碳排放。
研究组将20世纪60年月核弹实验发生的放射性碳的新预算与模子摹拟相连系，以评估陆地植被的碳轮回。成果发现，在耦合模式比对项目中利用的年夜大都最早进的植被模子都低估了植被生物量中的放射性碳堆集。
该发现连系对植被碳储量和出产力趋向的束缚，注解今朝净低级出产力可能最少为每一年800亿吨碳，而当前模子猜测的是每一年430至760亿吨碳。报酬碳在陆地植被中的贮存可能比此前猜测的更加短暂和懦弱。
▲ Abstract：
Vegetation and soils are taking up approximately 30% of anthropogenic carbon dioxide emissions because of small imbalances in large gross carbon exchanges from productivity and turnover that are poorly constrained. We combined a new budget of radiocarbon produced by nuclear bomb testing in the 1960s with model simulations to evaluate carbon cycling in terrestrial vegetation. We found that most state-of-the-art vegetation models used in the Coupled Model Intercomparison Project underestimated the radiocarbon accumulation in vegetation biomass. Our findings, combined with constraints on vegetation carbon stocks and productivity trends, imply that net primary productivity is likely at least 80 petagrams of carbon per year presently, compared with the 43 to 76 petagrams per year predicted by current models. Storage of anthropogenic carbon in terrestrial vegetation is likely more short-lived and vulnerable than previously predicted.
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