物理学Physics

▲ 作者：YUTARO TAKEUCH, YUMA SATO, YUTA YAMANE, JU-YOUNG YOON, YUKINORI KANNO, TOMOHIRO UCHIMURA, K. VIHANGA DE ZOYSA, JIAHAO HAN, SHUN KANAI, AND SHUNSUKE 

▲链接：

https://www.science.org/doi/10.1126/science.ado1611

▲摘要：

实现射频或更高频率下的反铁磁态电流驱动仍具挑战性。研究者报道了对手性反铁磁体锡锰合金（Mn3Sn）纳米点样品进行全电学千兆赫兹频段相干驱动的突破性进展。

在亚纳秒量级实现了多次试验的高相干性，且阈值电流对脉冲宽度不敏感——这一特性与铁磁体中的观测结果截然不同，从而实现了零场条件下0.1纳秒脉冲驱动的1000/1000次可靠翻转。

这些特征源于反铁磁激发的惯性特性。研究彰显了反铁磁自旋电子学在磁器件操作中兼具高速度与高效率的巨大潜力。

▲ Abstract：

Electric current driving of antiferromagnetic states at radio or higher frequencies remains challenging to achieve. In this study, we report all-electrical, gigahertz-range coherent driving of chiral antiferromagnet manganese-tin (Mn3Sn) nanodot samples. High coherence in multiple trials and threshold current insensitive to pulse width, in contrast to results observed with ferromagnets, were achieved in subnanosecond range, allowing 1000/1000 switching by 0.1-nanosecond pulses at zero field. These features are attributed to the inertial nature of antiferromagnetic excitations. Our study highlights the potential of antiferromagnetic spintronics to combine high speed and high efficiency in magnetic device operations.

▲ 作者：WEIXIN LIU, SIYU XU, AND CHENGKUO LEE 

▲链接：

https://www.science.org/doi/10.1126/science.adu8492

▲摘要：

实现动态任意光谱整形能力将通过提供卓越的频谱效率与网络灵活性，引发光子技术领域的革命。然而现有光学元件大多具有固定的光谱功能且可调性有限，制约了紧凑型快速光谱整形技术的发展。

研究者提出一种像素化纳米光机电（NOEM）光栅，通过机电诱导对称性破缺实现光栅耦合强度的像素级精确控制，从而研制出微型化（约0.007平方毫米）的光谱整形芯片。他们演示了基于光栅像素的任意光谱响应合成，并通过纳米级静电扰动集合效应，实现了快速（<10纳秒）、高对比度（>100分贝）的波长选择性开关。

这种像素化NOEM光栅以超紧凑的芯片形式提供卓越的光谱操控能力，为下一代光信息网络、计算架构等应用开辟了新前景。

▲ Abstract：

The ability to shape light spectra dynamically and arbitrarily would revolutionize many photonic systems by offering unparalleled spectral efficiency and network flexibility. However, most existing optical components have rigid spectral functionalities with limited tunability, hindering compact and fast optical spectral shaping. We introduce a pixelated nano-opto-electro-mechanical (NOEM) grating that exploits electromechanically induced symmetry breaking for precise, pixel-level control of grating coupling strength, yielding a miniaturized (~0.007 square millimeters) on-chip spectral shaper. We demonstrate the synthesis of grating pixels for arbitrary spectral responses, and we achieved rapid (<10 nanoseconds), high-contrast (>100 decibels), wavelength-selective switching through collective, nanometer-scale electrostatic perturbations. Our pixelated NOEM grating delivers exceptional spectral manipulation capabilities in an ultracompact, on-chip manner, offering prospects for next-generation optical information networks, computing architectures, and beyond.

▲ 作者：BRENT S. PEASE AND NEIL A. GILBERT 

▲链接：

https://www.science.org/doi/10.1126/science.adv9472

▲摘要：

光污染会破坏生物赖以生存的光暗周期节律。尽管现有研究（多聚焦于单一物种）已证实光污染会导致鸟类鸣叫晨化，但关于其对不同物种、地域和季节影响的系统性认知仍属空白。本研究基于全球声学数据集（超6000万条声学探测记录，涵盖583种昼行性鸟类），综合解析光污染对鸟类鸣叫行为的影响。

研究发现光污染平均使鸟类鸣叫时长延长50分钟。这种效应在具备大眼睛、露天巢穴、迁徙习性及广域分布特征的物种中尤为显著，且在繁殖季节最为强烈。活动时长延长可能对鸟类适应性产生负面、中性或积极影响；准确评估这些适应性效应并遏制光污染将成为21世纪保护生物学的重要挑战。

▲ Abstract：

Light pollution disrupts light–dark cues that organisms use as timetables for life. Although studies—typically focusing on individual species—have documented earlier morning onset of bird vocalization in light-polluted landscapes, a synthesis of light pollution effects across species, space, and season is lacking. We used a global acoustic dataset of more than 60 million detections, representing 583 diurnal bird species, to synthesize effects of light pollution on avian vocalization. On average, light pollution prolonged vocal activity by 50 min. Light pollution responses were strongest for species with large eyes, open nests, migratory habits, and large ranges and during the breeding season. Prolonged activity may confer negative, neutral, or positive fitness effects; documenting these fitness effects and curbing light pollution are challenges for 21st-century conservation.