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Science, 6 OCT 2023, VOL 382, ISSUE 6666

《明升体育app》2023年10月6日，第382卷，6666期

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物理学APhysics

An atomic-scale multi-qubit platform

原子级多量子比特平台

▲ 作者：Yu Wang, Yi Chen, Hong T. Bui, Christoph Wolf, Masahiro Haze, Cristina Mier, et al.

▲ 链接：http://www.science.org/doi/full/10.1126/science.ade5050

▲ 摘要：

固体中的单个电子自旋是量子明升体育app和技术颇有前途的候选者，长期以来人们一直在设想具有原子精确耦合的量子器件的自下而上组装。

研究组利用扫描隧道显微镜实现了耦合电子自旋量子比特的原子—原子构建、相干操作和读出。用邻近单原子磁体的局部磁场梯度来补充每个电子自旋，以实现对隧道结外“远程”量子比特的相干控制。

通过在隧道结中使用传感器量子比特并实现脉冲双电子自旋共振来实现读出。快速单、二、三量子比特运算得以全电方式展示。该研究的埃级量子比特平台可通过在表面上逐个原子地构建电子自旋阵列来实现量子功能。

▲ Abstract

Individual electron spins in solids are promising candidates for quantum science and technology, where bottom-up assembly of a quantum device with atomically precise couplings has long been envisioned. Here, we realized atom-by-atom construction, coherent operations, and readout of coupled electron-spin qubits using a scanning tunneling microscope. To enable the coherent control of “remote” qubits that are outside of the tunnel junction, we complemented each electron spin with a local magnetic field gradient from a nearby single-atom magnet. Readout was achieved by using a sensor qubit in the tunnel junction and implementing pulsed double electron spin resonance. Fast single-, two-, and three-qubit operations were thereby demonstrated in an all-electrical fashion. Our angstrom-scale qubit platform may enable quantum functionalities using electron spin arrays built atom by atom on a surface.

材料明升体育appMaterials Science

Transonic dislocation propagation in diamond

金刚石中的跨音速位错传播

▲ 作者：Kento Katagiri, Tatiana Pikuz, Lichao Fang, Bruno Albertazzi, Shunsuke Egashira, Yuichi Inubushi, et al.

▲ 链接：http://www.science.org/doi/full/10.1126/science.adh5563

▲ 摘要：

线缺陷（位错）的运动已研究了60多年，但位错移动的最大速度尚未解决。最近的模型和原子模拟预测在跨音速和亚音速范围内（位错自能发散）存在位错运动的极限速度，尽管这些模型不否认跨音速位错的可能性。

研究组使用飞秒X射线摄像来跟踪冲击压缩单晶金刚石中的超快位错运动，通过观察扩展速度快于金刚石最慢声波速度的堆垛层错，展示了部分位错在其前缘跨音速运动的证据。

了解晶体中位错迁移率的上限对于准确建模、预测和控制极端条件下材料的力学性能至关重要。

▲ Abstract

The motion of line defects (dislocations) has been studied for more than 60 years, but the maximum speed at which they can move is unresolved. Recent models and atomistic simulations predict the existence of a limiting velocity of dislocation motion between the transonic and subsonic ranges at which the self-energy of dislocation diverges, though they do not deny the possibility of the transonic dislocations. We used femtosecond x-ray radiography to track ultrafast dislocation motion in shock-compressed single-crystal diamond. By visualizing stacking faults extending faster than the slowest sound wave speed of diamond, we show the evidence of partial dislocations at their leading edge moving transonically. Understanding the upper limit of dislocation mobility in crystals is essential to accurately model, predict, and control the mechanical properties of materials under extreme conditions.

A quantum ruler for orbital magnetism in moiré quantum matter
莫尔量子物质中轨道磁性的量子标尺

▲ 作者：M. R. Slot, Y. Maximenko, P. M. Haney, S. Kim, D. T. Walkup, E. Strelcov, et al.

▲ 链接：http://www.science.org/doi/full/10.1126/science.adf2040

▲ 摘要：

近一个世纪以来，磁振荡一直是测量费米面拓扑结构的强大“量子标尺”。

研究组使用朗道能级光谱揭示了能量分辨谷对比轨道磁性和大轨道磁化率，这有助于转角双层—双层石墨烯的朗道能级能量。这些轨道磁力效应导致了与标准昂萨格关系的实质性偏差，表现为朗道能级轨道的标度分解。

这些实质性的磁响应来自于电子结构的非平凡量子几何和莫尔晶格势的大长度尺度。通过扫描隧道显微镜进行的朗道能级光谱学超越了传统的测量，提供了一个完整的量子标尺，解决了莫尔量子物质中轨道磁性质的全能量依赖性。

▲ Abstract

For almost a century, magnetic oscillations have been a powerful “quantum ruler” for measuring Fermi surface topology. In this study, we used Landau-level spectroscopy to unravel the energy-resolved valley-contrasting orbital magnetism and large orbital magnetic susceptibility that contribute to the energies of Landau levels of twisted double-bilayer graphene. These orbital magnetism effects led to substantial deviations from the standard Onsager relation, which manifested as a breakdown in scaling of Landau-level orbits. These substantial magnetic responses emerged from the nontrivial quantum geometry of the electronic structure and the large length scale of the moiré lattice potential. Going beyond traditional measurements, Landau-level spectroscopy performed with a scanning tunneling microscope offers a complete quantum ruler that resolves the full energy dependence of orbital magnetic properties in moiré quantum matter.

明升手机Chemistry

The oscillating Fischer-Tropsch reaction

振荡费托反应

▲ 作者：Rui Zhang, Yong Wang, Pierre Gaspard & Norbert Kruse

▲ 链接：http://www.science.org/doi/full/10.1126/science.adh8463

▲ 摘要：

人们对钴基催化剂（费托合成）在大气压下催化一氧化碳（CO）加氢过程中形成高级烃的机制步骤仍知之甚少。

研究组揭示了在220℃和反应物分压相等的条件下，钴与铈原子比为2:1 （Co2Ce1）的钴/铈氧化物催化剂在较长时间（>24小时）内自我维持的非等温速率和选择性振荡。

微观动力学机制通过强制温度振荡产生速率和选择性振荡。在更大的反应物压力比范围内，实验振荡和理论振荡非常一致。此外，烃类生产的相图得以构建，支持该研究中速率和选择性振荡的热力学起源。

▲ Abstract

The mechanistic steps that underlie the formation of higher hydrocarbons in catalytic carbon monoxide (CO) hydrogenation at atmospheric pressure over cobalt-based catalysts (Fischer-Tropsch synthesis) have remained poorly understood. We reveal nonisothermal rate-and-selectivity oscillations that are self-sustained over extended periods of time (>24 hours) for a cobalt/cerium oxide catalyst with an atomic ratio of cobalt to cerium of 2:1 (Co2Ce1) at 220°C and equal partial pressures of the reactants. A microkinetic mechanism was used to generate rate-and-selectivity oscillations through forced temperature oscillations. Experimental and theoretical oscillations were in good agreement over an extended range of reactant pressure ratios. Additionally, phase portraits for hydrocarbon production were constructed that support the thermokinetic origin of our rate-and-selectivity oscillations.

考古学Archaeology

More than 10,000 pre-Columbian earthworks are still hidden throughout Amazonia

亚马逊地区至今仍隐藏着一万多个前哥伦布时期的土方工程

▲ 作者：JVinicius Peripato, Carolina Levis, Guido A. Moreira, Dani Gamerman, Hans ter Steege, Nigel C. A. Pitman, et al.

▲ 链接：http://www.science.org/doi/full/10.1126/science.ade2541

▲ 摘要：

众所周知，土著社会已经在亚马逊流域生活了12000多年，但他们对亚马逊森林的影响程度仍不确定。

利用来自整个流域的激光雷达（光探测和测距）信息，研究组报道了在森林树冠下发现的24个此前未被发现的前哥伦布时期的土方工程。亚马逊地区大规模考古遗址的分布和丰度表明，仍有10272至23648个遗址有待发现，其中大多数隐藏在西南部。此外还确定了53种与土方工程发生概率显著相关的驯化树种，或表明了过去土著社会的管理实践。

亚马逊地区的封闭树冠森林可能包含数千个未被发现的考古遗址，前哥伦比亚社会在这些遗址周围积极改造森林，这一发现为更好地了解古代人类对亚马逊地区的影响程度及其现状提供了机会。

▲ Abstract

Indigenous societies are known to have occupied the Amazon basin for more than 12,000 years, but the scale of their influence on Amazonian forests remains uncertain. We report the discovery, using LIDAR (light detection and ranging) information from across the basin, of 24 previously undetected pre-Columbian earthworks beneath the forest canopy. Modeled distribution and abundance of large-scale archaeological sites across Amazonia suggest that between 10,272 and 23,648 sites remain to be discovered and that most will be found in the southwest. We also identified 53 domesticated tree species significantly associated with earthwork occurrence probability, likely suggesting past management practices. Closed-canopy forests across Amazonia are likely to contain thousands of undiscovered archaeological sites around which pre-Columbian societies actively modified forests, a discovery that opens opportunities for better understanding the magnitude of ancient human influence on Amazonia and its current state.

Independent age estimates resolve the controversy of ancient human footprints at White Sands

独立年龄估计解决了白沙古人类足迹的争议

▲ 作者：Jeffrey S. Pigati, Kathleen B. Springer, Jeffrey S. Honke, David Wahl, Marie R. Champagne, Susan R. H. Zimmerman, et al.

▲ 链接：http://www.science.org/doi/full/10.1126/science.adh5007

▲ 摘要：

据报道，美国新墨西哥州白沙国家公园的人类足迹可追溯到23000到21000年前，这是根据水生植物螺川蔓藻种子的放射性碳定年法测出的。该年龄仍存在争议，因为潜在的旧碳储层效应可能会影响其准确性。

研究组提出了从与螺川蔓藻种子相同地层层位收集的陆生花粉新校准14C年龄，以及来自人类足迹序列内沉积物的光学激发发光年龄，来评估种子年龄的准确性。结果表明，最初为白沙古人类足迹建立的时序框架是可靠的，并重申人类在末次盛冰期出现在北美。

▲ Abstract

Human footprints at White Sands National Park, New Mexico, USA, reportedly date to between ~23,000 and 21,000 years ago according to radiocarbon dating of seeds from the aquatic plant Ruppia cirrhosa. These ages remain controversial because of potential old carbon reservoir effects that could compromise their accuracy. We present new calibrated 14C ages of terrestrial pollen collected from the same stratigraphic horizons as those of the Ruppia seeds, along with optically stimulated luminescence ages of sediments from within the human footprint–bearing sequence, to evaluate the veracity of the seed ages. The results show that the chronologic framework originally established for the White Sands footprints is robust and reaffirm that humans were present in North America during the Last Glacial Maximum.