编译 | 李言

Nature, 27 April 2023, Volume 616 Issue 7958

《自然》2023年4月27日，第616卷，7958期

物理学Physics

Continuous symmetry breaking in a two-dimensional Rydberg array

二维里德堡阵列中连续对称性破缺

▲ 作者：Cheng Chen, Guillaume Bornet et al.

▲ 链接：

https://www.nature.com/articles/s41586-023-05859-2

▲ 摘要：

在此，我们用可编程的里德伯格量子模拟器实现了一个二维偶极XY模型，该模型具有连续的自旋对称性。我们证明了XY铁磁体和XY反铁磁体的相关低温态的绝热制备。

在铁磁情况下，我们表征了长程XY阶的存在，这是在没有长程偶极相互作用的情况下被禁止的特征。我们对XY相互作用的多体物理的探索，对最近使用里德伯格封锁机制来实现具有离散自旋对称的Ising型相互作用的工作进行了补充。

▲ Abstract：

Here, we realize a two-dimensional dipolar XY model that shows a continuous spin-rotational symmetry using a programmable Rydberg quantum simulator. We demonstrate the adiabatic preparation of correlated low-temperature states of both the XY ferromagnet and the XY antiferromagnet. In the ferromagnetic case, we characterize the presence of a long-range XY order, a feature prohibited in the absence of long-range dipolar interaction. Our exploration of the many-body physics of XY interactions complements recent works using the Rydberg-blockade mechanism to realize Ising-type interactions showing discrete spin rotation symmetry.

Build-up and dephasing of Floquet–Bloch bands on subcycle timescales

亚周期时间尺度上Floquet-Bloch带的建立和失相

▲ 作者：S. Ito, M. Schüler, M. Meierhofer et al.

▲ 链接：

https://www.nature.com/articles/s41586-023-05850-x

▲ 摘要：

在此，我们用时间分辨和角度分辨的光电发射光谱来展示Floquet-Bloch带的超快建立过程。我们利用中红外场在驱动拓扑绝缘体表面中驱动，产生足够强的高次谐波，并以亚周期时间分辨率直接监测瞬态带结构。

从强带内电流开始，我们观察到Floquet侧带是如何在单个光周期内出现的，多个侧带同时进行带内加速，直到高能电子散射到体态，耗散破坏了Floquet带。

量子非平衡计算解释了带内和带间动力学同时发生的Floquet态。我们的联合实验和理论研究提供了Floquet物理的直接时域视图，同时探索了超快带结构工程的基础前沿。

▲ Abstract：

Here we provide this link by visualizing the ultrafast build-up of Floquet–Bloch bands with time-resolved and angle-resolved photoemission spectroscopy. We drive surface states on a topological insulator with mid-infrared fields—strong enough for high-harmonic generation—and directly monitor the transient band structure with subcycle time resolution. Starting with strong intraband currents, we observe how Floquet sidebands emerge within a single optical cycle; intraband acceleration simultaneously proceeds in multiple sidebands until high-energy electrons scatter into bulk states and dissipation destroys the Floquet bands. Quantum non-equilibrium calculations explain the simultaneous occurrence of Floquet states with intraband and interband dynamics. Our joint experiment and theory study provides a direct time-domain view of Floquet physics and explores the fundamental frontiers of ultrafast band-structure engineering.

材料科学Material science

Tracing attosecond electron emission from a nanometric metal tip

纳米金属尖端的阿秒电子发射

▲ 作者：Philip Dienstbier, Lennart Seiffert et al.

▲ 链接：

https://www.nature.com/articles/s41586-023-05839-6

▲ 摘要：

在此，我们展示了后向散射电子的双色调制光谱在阿秒精度上，如何揭示纳米结构的亚光周期强场发射动力学。我们的实验测量了从尖锐的金属尖端发射的电子的光电子能谱作为两种颜色之间相对相位的函数。

通过将时间相关Schrödinger方程的解投影到经典轨迹上，我们把光谱中的相位相关特征与发射动力学联系起来，并通过将量子模型与实验相匹配，得到710±30阿秒的发射持续时间。

我们的研究结果为固态和其他系统的强场光发射的定量定时和精确主动控制打开了大门，并对超快电子源、量子简并研究和亚泊松电子束、纳米等离子体学和皮赫兹电子学等多个领域产生直接影响。

▲ Abstract：

Here we show that two-colour modulation spectroscopy of backscattering electrons uncovers the suboptical-cycle strong-field emission dynamics from nanostructures, with attosecond precision. In our experiment, photoelectron spectra of electrons emitted from a sharp metallic tip are measured as function of the relative phase between the two colours. Projecting the solution of the time-dependent Schrödinger equation onto classical trajectories relates phase-dependent signatures in the spectra to the emission dynamics and yields an emission duration of 710±30attoseconds by matching the quantum model to the experiment. Our results open the door to the quantitative timing and precise active control of strong-field photoemission from solid state and other systems and have direct ramifications for diverse fields such as ultrafast electron sources, quantum degeneracy studies and sub-Poissonian electron beams, nanoplasmonics and petahertz electronics.

pH-dependent water permeability switching and its memory in MoS2 membranes

二硫化钼膜中ph依赖的水透性转换及其记忆

▲ 作者：C. Y. Hu, A. Achari, P. Rowe, H. Xiao, S. Suran et al.

▲ 链接：

https://www.nature.com/articles/s41586-023-05849-4

▲ 摘要：

在此，我们展示了分子通过智能相变二硫化钼膜对外部pH值的记忆效应和刺激性调节的运输。我们表明，水和离子通过1T 二硫化钼膜的渗透遵循pH依赖的滞后，其渗透速率转换几个数量级。我们确定这种现象是二硫化钼的1T 相所特有的，原因是表面电荷和表面交换离子的存在。我们进一步证明了这种现象在自主伤口感染监测和ph依赖的纳米过滤中的潜在应用。我们的研究加深了对纳米尺度水传输机制的理解，为智能膜的开发开辟了一条途径。

▲ Abstract：

Here we demonstrate the memory effects and stimuli-regulated transport of molecules through an intelligent, phase-changing MoS2membrane in response to external pH. We show that water and ion permeation through 1T′ MoS2membranes follows a pH-dependent hysteresis with a permeation rate that switches by a few orders of magnitude. We establish that this phenomenon is unique to the 1T′ phase of MoS2, due to the presence of surface charge and exchangeable ions on the surface. We further demonstrate the potential lication of this phenomenon in autonomous wound infection monitoring and pH-dependent nanofiltration. Our work deepens understanding of the mechanism of water transport at the nanoscale and opens an avenue for the development of intelligent membranes.

人工智能Artificial Intelligence

Human–machine collaboration for improving semiconductor process development

用于改进半导体工艺开发的人机协作

▲ 作者：Keren J. Kanarik, Wojciech T. Osowiecki et al.

▲ 链接

https://www.nature.com/articles/s41586-023-05773-7

▲ 摘要：

在此，我们通过贝叶斯优化算法，研究人工智能如何降低开发复杂半导体芯片工艺的成本。

我们创建了一个受控的虚拟过程游戏，以系统地基准测试人类和计算机在半导体制造过程设计的情况。我们发现人类工程师在开发的早期阶段表现出色，而算法在接近目标的严格公差时更具成本效益。

此外，我们表明，与仅使用人类设计师相比，使用具有高专业知识的人类设计师和算法且实行人类设计师优先的策略，可以将目标成本降低一半。最后，我们强调了在开发半导体过程中引入人工智能时需要解决的人类与计算机合作中的文化挑战。

▲ Abstract：

Here we study Bayesian optimization algorithms to investigate how artificial intelligence (AI) might decrease the cost of developing complex semiconductor chip processes. In particular, we create a controlled virtual process game to systematically benchmark the performance of humans and computers for the design of a semiconductor fabrication process. We find that human engineers excel in the early stages of development, whereas the algorithms are far more cost-efficient near the tight tolerances of the target. Furthermore, we show that a strategy using both human designers with high expertise and algorithms in a human first–computer last strategy can reduce the cost-to-target by half compared with only human designers. Finally, we highlight cultural challenges in partnering humans with computers that need to be addressed when introducing artificial intelligence in developing semiconductor processes.

地理学Geography

Net greenhouse gas balance of fibre wood plantation on peat in Indonesia

印尼泥炭纤维木材种植的净温室气体平衡

▲ 作者：Chandra S. Deshmukh, Ari P. Susanto et al.

▲ 链接：

https://www.nature.com/articles/s41586-023-05860-9

▲ 摘要：

在这里，我们测量了年10月至2022年5月期间，在相同的泥炭地中，相思人工林、退化森林和完整森林的二氧化碳、甲烷和土壤一氧化二氮的净生态系统交换通量，这些代表了印度尼西亚苏门答腊岛的土地覆盖变化轨迹。这使我们能够呈现泥炭地纤维木人工林的完整轮作温室气体通量平衡。

研究发现，尽管金合欢人工林的土地利用强度更高，但其温室气体排放量低于平均地下水位（GWL）相似的退化地区。在一个完整的轮作过程中，金合树人工林的温室气体排放量约为完整森林的两倍，但仅为目前政府间气候变化专门委员会一级排放因子对此种土地用途规定的一半。

我们的研究结果可以帮助减少温室气体排放估算的不确定性，提供土地利用变化对热带泥炭的影响估算，并制定基于科学的泥炭地管理实践作为基于自然的气候解决方案。

▲ Abstract：

Here we measure net ecosystem exchanges of carbon dioxide, methane and soil nitrous oxide fluxes between October and May 2022 from Acacia crassicarpa plantation, degraded forest and intact forest within the same peat landscape, representing land-cover-change trajectories in Sumatra, Indonesia. This allows us to present a full plantation rotation GHG flux balance in a fibre wood plantation on peatland. We find that the Acacia plantation has lower GHG emissions than the degraded site with a similar average groundwater level (GWL), despite more intensive land use. The GHG emissions from the Acacia plantation over a full plantation rotation (35.2±4.7tCO2-eq ha−1year−1, average±standard deviation) were around two times higher than those from the intact forest (20.3±3.7tCO2-eqha−1year−1), but only half of the current Intergovernmental Panel on Climate Change (IPCC) Tier 1 emission factor (EF) for this land use. Our results can help to reduce the uncertainty in GHG emissions estimates, provide an estimate of the impact of land-use change on tropical peat and develop science-based peatland management practices as nature-based climate solutions.