编译 | 冯维维
Nature, 21 May 2020, Volume 581 Issue 7808
《自然》2020年5月21日，第581卷，7808期
物理学Physics
A cold, massive, rotating disk galaxy 1.5 billion years after the Big Bang
早期盘状星系挑战传统的星系形成模型
▲ 作者：Marcel Neeleman, J. Xavier Prochaska, Nissim Kanekar,Marc Rafelski, etc.
▲ 链接：https://www.nature.com/articles/s41586-020-2276-y
▲ 摘要
在传统的星系形成模型中，像银河系这样的大质量盘状星系预计会在晚期形成，最近的数值模拟表明，这样的星系可能早在大爆炸后10亿年就通过冷物质的吸积和合并形成了。
通过检测其类星体光的吸收识别，作者报告了一个红移为4.2603的星系。这些观测结果表明，辐射来自于一个旋转速度约为每秒272公里的冰冷、多尘的旋转圆盘内的气体。研究者探测到星系中一氧化碳的排放，得到的分子质量与估计的约720亿太阳质量的电离碳排放相一致。
当宇宙只有15亿岁的时候，这样一个巨大的、旋转支撑的冷盘星系的存在有利于通过冷模式的吸积或合并形成，尽管它的大旋转速度和大冷气体含量仍然很难用大多数的数值模拟重现。
▲ Abstract
Massive disk galaxies like the Milky Way are expected to form at late times in traditional models of galaxy formation, but recent numerical simulations suggest that such galaxies could form as early as a billion years after the Big Bang through the accretion of cold material and mergers. Here we report imaging, with a resolution of about 1.3 kiloparsecs, of the 158-micrometre emission line from singly ionized carbon, the far-infrared dust continuum and the near-ultraviolet continuum emission from a galaxy at a redshift of 4.2603, identified by detecting its absorption of quasar light. These observations show that the emission arises from gas inside a cold, dusty, rotating disk with a rotational velocity of about 272 kilometres per second. The detection of emission from carbon monoxide in the galaxy yields a molecular mass that is consistent with the estimate from the ionized carbon emission of about 72 billion solar masses. The existence of such a massive, rotationally supported, cold disk galaxy when the Universe was only 1.5 billion years old favours formation through either cold-mode accretion or mergers, although its large rotational velocity and large content of cold gas remain challenging to reproduce with most numerical simulations.
Quantum entanglement between an atom and a molecule
原子和分子之间的量子纠缠
▲ 作者：Yiheng Lin, David R. Leibrandt, Dietrich Leibfried,Chin-wen Chou, etc.
▲ 链接：https://www.nature.com/articles/s41586-020-2257-1
▲ 摘要
传统的信息处理器将信息在不同的物理载体之间进行转换、处理、存储和传输。
作者证明了40CaH+分子离子的旋转态和40Ca+原子离子的内部态之间的纠缠。他们扩展了量子逻辑光谱学中用于分子离子的纯态初始化、激光操作和状态读出的方法。
原子和分子离子之间库仑耦合运动的量子相干性，使后续的纠缠操作成为可能。该分子中的量子位具有13.4千赫兹或855千兆赫的频率，突出了分子量子位的多功能性。
作者演示了分子如何在不同频率的量子位元之间传递量子信息，从而实现混合量子系统。他们期望这一分子量子控制和测量方法在量子信息科学、量子传感器、基础和应用物理以及受控量子化学中得到应用。
▲ Abstract
Conventional information processors convert information between different physical carriers for processing, storage and transmission. Here we demonstrate entanglement between the rotational states of a 40CaH+molecular ion and the internal states of a 40Ca+ atomic ion. We extend methods used in quantum logic spectroscopy for pure-state initialization, laser manipulation and state readout of the molecular ion. The quantum coherence of the Coulomb coupled motion between the atomic and molecular ions enables subsequent entangling manipulations. The qubit addressed in the molecule has a frequency of either 13.4 kilohertz1 or 855 gigahertz, highlighting the versatility of molecular qubits. Our work demonstrates how molecules can transduce quantum information between qubits with different frequencies to enable hybrid quantum systems. We anticipate that our method of quantum control and measurement of molecules will find applications in quantum information science, quantum sensors, fundamental and applied physics, and controlled quantum chemistry.
仿生学Bionics
A biomimetic eye with a hemispherical perovskite nanowire array retina
机器仿生眼
▲ 作者：Leilei Gu, Swapnadeep Poddar, Yuanjing Lin, Zhenghao Long, Ali Javey, Zhiyong Fan, etc.
▲ 链接：https://www.nature.com/articles/s41586-020-2285-x
▲ 摘要
人眼具有极宽视场、高分辨率、低像差等特殊的图像传感特性。
作者描述了一个电化学眼睛与半球形视网膜组成的高密度纳米线阵列模拟的人类视网膜上的光感受器。该设备的设计与人眼的结构高度相似，当单个纳米线在进行电处理时，有可能实现高成像分辨率。
此外，作者通过重建投射到该仿生装置上的光学模式，展示了其图像传感功能。作者表示，研究将推动仿生光敏器件的广泛应用。
▲ Abstract
Human eyes possess exceptional image-sensing characteristics such as an extremely wide field of view, high resolution and sensitivity with low aberration. Here we present an electrochemical eye with a hemispherical retina made of a high-density array of nanowires mimicking the photoreceptors on a human retina. The device design has a high degree of structural similarity to a human eye with the potential to achieve high imaging resolution when inpidual nanowires are electrically addressed. Additionally, we demonstrate the image-sensing function of our biomimetic device by reconstructing the optical patterns projected onto the device. This work may lead to biomimetic photosensing devices that could find use in a wide spectrum of technological applications.
物理化学
Physical Chemistry
Short-range order and its impact on the CrCoNi medium-entropy alloy
短程有序结构影响CrCoNi中熵合金性能
▲ 作者：Ruopeng Zhang, Shiteng Zhao, Jun Ding, Yan Chong, Tao Jia, Andrew M. Minor, etc.
▲ 链接：https://www.nature.com/articles/s41586-020-2275-z
▲ 摘要
传统的金属合金是元素的混合物，其中少数种类的原子在低于其溶解度限制时倾向于随机分布，在高于溶解度限制时则形成第二相。
作者报告了利用能量过滤透射电子显微镜观察到的中熵合金中可归结为短程排列的结构特征。这种顺序的增加会导致更高的叠加故障能量和硬度。
这些结果表明，纳米尺度的局部有序度可以通过热机械加工来调整，为调整中、高熵合金的力学性能提供了新的途径。
▲ Abstract
Traditional metallic alloys are mixtures of elements in which the atoms of minority species tend to be distributed randomly if they are below their solubility limit, or to form secondary phases if they are above it. Here we report the observation, using energy-filtered transmission electron microscopy, of structural features attributable to short-range order in the CrCoNi medium-entropy alloy. Increasing amounts of such order give rise to both higher stacking-fault energy and hardness. These findings suggest that the degree of local ordering at the nanometre scale can be tailored through thermomechanical processing, providing a new avenue for tuning the mechanical properties of medium- and high-entropy alloys.
地球科学Geoscience
Patterns and trends of Northern Hemisphere snow mass from 1980 to 2018
1980年至2018年北半球积雪的态势
▲ 作者：Jouni Pulliainen, Kari Luojus, Chris Derksen, Lawrence Mudryk, Johannes Norberg, etc.
▲ 链接：https://www.nature.com/articles/s41586-020-2258-0
▲ 摘要
全球变暖导致北半球冰雪覆盖范围和持续时间显著减少。作者使用新的GlobSnow 3.0数据集显示，1980-2018年北半球年最大积雪量平均为3062±350亿吨。
作者对3月份的数据进行了量化（与积雪量峰值最接近)，覆盖了40°N以上的非高山地区，最重要的是，还包括了基于现场积雪观测的偏差校正。
作者将GlobSnow 3.0估计数与三个独立的积雪量估计数进行比较，每个估计数都有或没有偏差校正。在四个数据集中，偏差校正将范围从2433亿2~3380亿吨减少到2846 - 3062亿吨——不确定度从33%减少到7.4%。
作者发现在39年的卫星记录中，不同的大陆趋势有所不同。例如，北美地区的积雪量每10年减少460亿吨，而欧亚地区的趋势可以忽略不计；两大洲都表现出高度的区域差异。研究有助于更好地估计季节性积雪在地球能源、水和碳预算中的作用。
▲ Abstract
Warming surface temperatures have driven a substantial reduction in the extent and duration of Northern Hemisphere snow cover. Here we use the new GlobSnow 3.0 dataset to show that the 1980–2018 annual maximum snow mass in the Northern Hemisphere was, on average, 3,062 ± 35 billion tonnes (gigatonnes). Our quantification is for March (the month that most closely corresponds to peak snow mass), covers non-alpine regions above 40° N and, crucially, includes a bias correction based on in-field snow observations. We compare our GlobSnow 3.0 estimates with three independent estimates of snow mass, each with and without the bias correction. Across the four datasets, the bias correction decreased the range from 2,433–3,380 gigatonnes (mean 2,867) to 2,846–3,062 gigatonnes (mean 2,938)—a reduction in uncertainty from 33% to 7.4%. On the basis of our bias-corrected GlobSnow 3.0 estimates, we find different continental trends over the 39-year satellite record. For example, snow mass decreased by 46 gigatonnes per decade across North America but had a negligible trend across Eurasia; both continents exhibit high regional variability. Our results enable a better estimation of the role of seasonal snow mass in Earth’s energy, water and carbon budgets.
古人类学
Paleoanthropology
Initial Upper Palaeolithic Homo sapiens from Bacho Kiro Cave, Bulgaria
最早的旧石器时代晚期智人或来自保加利亚
▲ 作者：Jean-Jacques Hublin, Nikolay Sirakov, Tsenka Tsanova, etc.
▲ 链接：https://www.nature.com/articles/s41586-020-2259-z
▲ 摘要
在欧洲旧石器时代中期至晚期的过渡时期，非洲的智人取代了当地的尼安德特人，并在一定程度上吸收了尼安德特人。
作者报告了人类遗骸的发现和直接年代测定，这些遗骸与早期旧石器时代晚期的文物有关，来自保加利亚巴乔基罗洞穴。
作者通过对蛋白质组学筛选鉴定的一颗牙齿和几块古人类骨骼碎片的线粒体DNA进行的形态学分析，将这些发现认定为智人，并将早期旧石器时代晚期 科技 的扩张与智人在4.5万年前向欧亚大陆中纬度地区的传播联系起来。
这次挖掘出土了大量的骨制品，包括用洞穴熊的牙齿制作的吊坠，让人想起后来由西欧最后的尼安德特人制作的东西。这些发现与之前的模型是一致的，这些模型是基于智人与尼安德特人不断减少的人口之间的多次迁徙。
▲ Abstract
The Middle to Upper Palaeolithic transition in Europe witnessed the replacement and partial absorption of local Neanderthal populations by Homo sapiens populations of African origin. Here we report the discovery and direct dating of human remains found in association with Initial Upper Palaeolithic artefacts, from excavations at Bacho Kiro Cave (Bulgaria). Morphological analysis of a tooth and mitochondrial DNA from several hominin bone fragments, identified through proteomic screening, assign these finds to H. sapiens and link the expansion of Initial Upper Palaeolithic technologies with the spread of H. sapiens into the mid-latitudes of Eurasia before 45 thousand years ago. The excavations yielded a wealth of bone artefacts, including pendants manufactured from cave bear teeth that are reminiscent of those later produced by the last Neanderthals of western Europe. These finds are consistent with models based on the arrival of multiple waves of H. sapiens into Europe coming into contact with declining Neanderthal populations.