大物论文量子物理

编译 | 李言

Science , 07 MAY 2021, VOL 372, ISSUE 6542

《科学》 2021年5月7日，第372卷，6542期

古人类学 Paleoanthropology

Unearthing Neanderthal population history using nuclear and mitochondrial DNA from cave sediments

利用洞穴沉积物中的核和线粒体DNA挖掘尼安德特人的种群 历史

作者：Benjamin Vernot, Elena I. Zavala, Asier Gómez-Olivencia, Zenobia Jacobs, et al.

链接：

摘要

骨头和牙齿是更新世人类DNA的重要来源，但很少在考古遗址中发现。从洞穴沉积物中可以提取到线粒体DNA（mtDNA），但它们对种群关系的研究价值有限。

因此，我们开发了收集和分析沉积物中核DNA的方法，并将其应用于20万至5万年前的西欧和西伯利亚南部的洞穴沉积物中。

我们在大约10万年前的西班牙北部发现了一个伴随着mtDNA更替的种群更替。我们还确定了尼安德特人在晚更新世早期的两次辐射进化事件。我们的工作为从沉积物中微量的核DNA研究古人类的种群 历史 奠定了基础。

Abstract

Bones and teeth are important sources of Pleistocene hominin DNA, but are rarely recovered at archaeological sites. Mitochondrial DNA (mtDNA) has been retrieved from cave sediments but provides limited value for studying population relationships. We therefore developed methods for the enrichment and analysis of nuclear DNA from sediments and applied them to cave deposits in western Europe and southern Siberia dated to between 200,000 and 50,000 years ago. We detected a population replacement in northern Spain about 100,000 years ago, which was accompanied by a turnover of mtDNA. We also identified two radiation events in Neanderthal history during the early part of the Late Pleistocene. Our work lays the ground for studying the population history of ancient hominins from trace amounts of nuclear DNA in sediments.

古生物学 Paleobiology

Evolution of vision and hearing modalities in theropod dinosaurs

兽脚类恐龙视觉和听觉模式的进化

作者：Jonah N. Choiniere, James M. Neenan, Lars Schmitz, David P. Ford, et al.

链接：

摘要

猫头鹰和夜莺是在夜间活动的猎食者，它们结合了视觉和听觉的改变，以克服在弱光下感官表现的限制。这种感官改变在非鸟类的兽脚类恐龙中未被发现，并且在向鸟类进化的谱系中极少被确认。

我们研究了现存和灭绝的兽脚亚目动物的视觉和听觉的形态功能代理，并证明了感官模式的深度进化分歧。夜行性捕食在非鸟类的阿瓦拉慈龙类早期就进化出来了，表现为极弱的视力和听觉敏感度的增加。

晚白垩纪的沙漠鸟面龙拥有更特殊的听力，可以与今天的仓鸮媲美。早在现代鸟类辐射进化出现之前，这种感觉适应能力的结合就在恐龙身上独立进化，并为恐龙和哺乳动物的融合提供了一个显著的例子。

Abstract

Owls and nightbirds are nocturnal hunters of active prey that combine visual and hearing adaptations to overcome limits on sensory performance in low light. Such sensory innovations are unknown in nonavialan theropod dinosaurs and are poorly characterized on the line that leads to birds. We investigate morphofunctional proxies of vision and hearing in living and extinct theropods and demonstrate deep evolutionary pergences of sensory modalities. Nocturnal predation evolved early in the nonavialan lineage Alvarezsauroidea, signaled by extreme low-light vision and increases in hearing sensitivity. The Late Cretaceous alvarezsauroid Shuvuuia deserti had even further specialized hearing acuity, rivaling that of today’s barn owl. This combination of sensory adaptations evolved independently in dinosaurs long before the modern bird radiation and provides a notable example of convergence between dinosaurs and mammals.

材料科学 Materials Science

Reversible fusion and fission of graphene oxide–based fibers

氧化石墨烯纤维的可逆融合和分裂

作者：Dan Chang, Jingran Liu, Bo Fang, Zhen Xu, et al.

链接：

摘要

刺激反应融合和分裂在生物组织和人工分子组装中被广泛观察到。然而，在重复聚变和分裂的过程中，设计一个结构和性能持久的系统仍然具有挑战性。

我们研究了氧化石墨烯（GO）纤维的可逆融合和分裂，在溶剂的刺激下，许多宏观纤维可以融合成较厚的纤维，也可以分离成原始的单个纤维。

氧化石墨烯纤维壳层由溶剂蒸发和渗透引起的动态几何变形是实现可逆聚变-裂变循环的关键。这一原理被扩展到实现复杂纤维组件和客体化合物的包含或排出之间的灵活转化。

Abstract

Stimuli-responsive fusion and fission are widely observed in both bio-organizations and artificial molecular assemblies. However, the design of a system with structure and property persistence during repeated fusion and fission remains challenging. We show reversible fusion and fission of wet-spun graphene oxide (GO) fibers, in which a number of macroscopic fibers can fuse into a thicker one and can also separate into original inpidual fibers under stimulation of solvents. The dynamic geometrical deformation of GO fiber shells, caused by solvent evaporation and infiltration, is the key to the reversible fusion-fission cycles. This principle is extended to implement flexible transitions between complex fiber assemblies and the inclusion or expulsion of guest compounds.

量子物理 Quantum Physics

Direct observation of deterministic macroscopic entanglement

宏观物体量子纠缠的直接证据

作者：Shlomi Kotler, Gabriel A. Peterson, Ezad Shojaee, Florent Lecocq, et al.

链接：

摘要

机械系统的量子纠缠是在不同的物体运动时产生的，它们之间的关联程度如此之高，以至于不能够被单独描述。

虽然量子力学可能适用于各种大小的物体，但随着质量的增加，直接观测纠缠变得具有挑战性，需要以极小的误差进行测量和控制。

在这里，使用脉冲电学，我们确定地使质量为70微克的两个机械鼓面纠缠在一起。通过近量子极限测量两个鼓的位置和动量积分，我们进行了量子态断层扫描，从而直接观察纠缠。

这种纠缠的宏观系统将在量子力学的基础测试中发挥作用，使感知超越标准量子极限成为可能，并作为未来量子网络的长期网络节点发挥作用。

Abstract

Quantum entanglement of mechanical systems emerges when distinct objects move with such a high degree of correlation that they can no longer be described separately. Although quantum mechanics presumably applies to objects of all sizes, directly observing entanglement becomes challenging as masses increase, requiring measurement and control with a vanishingly small error. Here, using pulsed electromechanics, we deterministically entangle two mechanical drumheads with masses of 70 picograms. Through nearly quantum-limited measurements of the position and momentum quadratures of both drums, we perform quantum state tomography and thereby directly observe entanglement. Such entangled macroscopic systems are poised to serve in fundamental tests of quantum mechanics, enable sensing beyond the standard quantum limit, and function as long-lived nodes of future quantum networks.

Quantum mechanics–free subsystem with mechanical oscillators

带有机械振荡器的无量子力学子系统

作者：Laure Mercier de Lépinay, Caspar F. Ockeloen-Korppi, Matthew J. Woolley, Mika A. Sillanpää

链接：

摘要

量子力学为连续测量振荡器位置的精度设定了一个极限。我们通过构造一个有效的振荡器，展示了如何测量一个没有测量量子反作用的振荡器。

我们利用两个微机械振荡器实现了这样一个不涉及量子力学的子系统，并显示了两个集体求积的测量结果，同时对它们都避开了8分贝的量子反作用，获得了一个在完全量子极限的2倍以内的总噪声。

这有助于弱力的检测和振荡器非经典运动状态的产生和测量。此外，我们通过测量在可分性界下分贝的段量，直接验证了两个振荡器的量子纠缠。

Abstract

Quantum mechanics sets a limit for the precision of continuous measurement of the position of an oscillator. We show how it is possible to measure an oscillator without quantum back-action of the measurement by constructing one effective oscillator from two physical oscillators. We realize such a quantum mechanics–free subsystem using two micromechanical oscillators, and show the measurements of two collective quadratures while evading the quantum back-action by 8 decibels on both of them, obtaining a total noise within a factor of 2 of the full quantum limit. This facilitates the detection of weak forces and the generation and measurement of nonclassical motional states of the oscillators. Moreover, we directly verify the quantum entanglement of the two oscillators by measuring the Duan quantity decibels below the separability bound.

动物学 Zoology

Extreme altitudes during diurnal flights in a nocturnal songbird migrant

夜间鸣禽候鸟在日间飞行时的极端高度

作者：Sissel Sjöberg, Gintaras Malmiga, Andreas Nord, Arne Andersson, et al.

链接：

摘要

数十亿只夜间迁徙的鸣禽每年都会飞越海洋和沙漠。通过使用多传感器数据记录器，我们发现，大苇莺（Acrocephalus arundinaceus）在穿越地中海和撒哈拉沙漠时，会定期将它们本来只能在夜间飞行的飞行时间延长至白天。

出乎意料的是，当延长飞行时间时，他们在黎明时陡然攀升，从平均海拔2394米上升到日间飞行的极端高度（平均海拔5367米，最高海拔6267米）。

这种以前不为人知的在白天迁徙时使用非常高的飞行高度的行为可能是由环境温度、风、捕食、视野范围和太阳辐射的日变化引起的。我们对这一行为的发现为鸟类飞行限制提供了新的视角，并可能有助于解释夜间迁徙的进化。

Abstract

Billions of nocturnally migrating songbirds fly across oceans and deserts on their annual journeys. Using multisensor data loggers, we show that great reed warblers (Acrocephalus arundinaceus) regularly prolong their otherwise strictly nocturnal flights into daytime when crossing the Mediterranean Sea and the Sahara Desert. Unexpectedly, when prolonging their flights, they climbed steeply at dawn, from a mean of 2394 meters above sea level to reach extreme cruising altitudes (mean 5367 and maximum 6267 meters above sea level) during daytime flights. This previously unknown behavior of using exceedingly high flight altitudes when migrating during daytime could be caused by diel variation in ambient temperature, winds, predation, vision range, and solar radiation. Our finding of this notable behavior provides new perspectives on constraints in bird flight and might help to explain the evolution of nocturnal migration.