物理学Physics

▲ 作者：MARIUS BILD, MATTEO FADEL, YU YANG, UWE VON LÜPKE, PHILLIP MARTIN, ALESSANDRO BRUNO, ET AL.

▲ 链接：

https://www.science.org/doi/10.1126/science.adf7553

▲ 摘要：

根据量子力学，一个物理系统可处于其可能状态的任何线性叠加态中。尽管这一原理的有效性在微观系统中得到了常规验证，但人们仍不清楚为何无法观察到宏观物体处于可通过某些经典性质区分的叠加态中。

研究组演示了在薛定谔猫运动状态下的机械谐振器的制备，其中约10¹⁷个组成原子处于两个相反相位振荡的叠加态中。他们控制了叠加态的大小和相位，并研究了叠加态的退相干动力学。

该研究结果为探索量子世界和经典世界之间的边界提供了可能性，并有望在连续变量量子信息处理和机械谐振器计量中找到应用途径。

▲ Abstract：

According to quantum mechanics, a physical system can be in any linear superposition of its possible states. Although the validity of this principle is routinely validated for microscopic systems, it is still unclear why we do not observe macroscopic objects to be in superpositions of states that can be distinguished by some classical property. Here we demonstrate the preparation of a mechanical resonator in Schrödinger cat states of motion, where the ∼10¹⁷ constituent atoms are in a superposition of two opposite-phase oscillations. We control the size and phase of the superpositions and investigate their decoherence dynamics. Our results offer the possibility of exploring the boundary between the quantum and classical worlds and may find applications in continuous-variable quantum information processing and metrology with mechanical resonators.

信息科学Information Science

▲ 作者：ZELIN MA, POUL KRISTENSEN, AND SIDDHARTH RAMACHANDRAN

▲ 链接：

https://www.science.org/doi/10.1126/science.add1874

▲ 摘要：

光纤中的空间模式计数可扩展性对于解决即将到来的信息容量紧缩、降低每比特能耗以及实现先进的量子计算网络至关重要，但这种可扩展性严重受制于微扰模式混合。

研究组展示了一种光导替代方法，光的轨道角动量为其自身创建了一个离心势垒，从而在传统禁止状态下实现光的低损耗传输，并顺理成章地减少了模式混合。

在130纳米的电信频谱窗口内，研究组实现了创纪录的约50个低损耗模式的千米级距离传输，串扰低至- 45分贝/千米，模式面积约为800平方微米。这种独特的光导机制有望大幅增加量子网络或经典网络中每个光子的信息量。

▲ Abstract：

Spatial mode-count scalability in optical fibers is of paramount importance for addressing the upcoming information-capacity crunch, reducing energy consumption per bit, and for enabling advanced quantum computing networks, but this scalability is severely limited by perturbative mode mixing. We show an alternative means of light guidance, in which light’s orbital angular momentum creates a centrifugal barrier for itself, thereby enabling low-loss transmission of light in a conventionally forbidden regime wherein the mode mixing can be naturally curtailed. This enables kilometer-length-scale transmission of a record ~50 low-loss modes with cross-talk as low as −45 decibels/kilometer and mode areas of ~800 square micrometers over a 130-nanometer telecommunications spectral window. This distinctive light-guidance regime promises to substantially increase the information content per photon for quantum or classical networks.

▲ 作者：ISAAC D. LUTZ, SHUNZHI WANG, CHRISTOFFER NORN, ALEXIS COURBET, ANDREW J. BORST, YAN TING ZHAO, ET AL.

▲ 链接：

https://www.science.org/doi/10.1126/science.adf6591

▲ 摘要：

作为进化选择的结果，天然存在的蛋白质组件亚基通常以牢固的形状互补性结合在一起，以当前设计方法无法实现的方式产生功能最佳的结构。

研究组描述了一种“自上而下”的基于强化学习的设计方法，使用蒙特卡洛树搜索在整体架构和特定功能约束的背景下对蛋白质构象异构体进行采样，从而解决了这个问题。所设计的碟状纳米孔和超紧致二十面体的冷冻电镜结构与计算机模型非常接近。

二十面体能够超高密度地显示免疫原和信号分子，从而增强疫苗反应和血管生成诱导。该方法实现了具有所需系统特性的复杂蛋白质纳米材料的自上而下设计，并证明了强化学习在蛋白质设计中的强大能力。

▲ Abstract：

As a result of evolutionary selection, the subunits of naturally occurring protein assemblies often fit together with substantial shape complementarity to generate architectures optimal for function in a manner not achievable by current design approaches. We describe a “top-down” reinforcement learning–based design approach that solves this problem using Monte Carlo tree search to sample protein conformers in the context of an overall architecture and specified functional constraints. Cryo–electron microscopy structures of the designed disk-shaped nanopores and ultracompact icosahedra are very close to the computational models. The icosohedra enable very-high-density display of immunogens and signaling molecules, which potentiates vaccine response and angiogenesis induction. Our approach enables the top-down design of complex protein nanomaterials with desired system properties and demonstrates the power of reinforcement learning in protein design.

地球科学Earth Science

▲ 作者：H.-O. PÖRTNER, R. J. SCHOLES, A. ARNETH, D. K. A. BARNES, M. T. BURROWS, S. E. DIAMOND, ET AL.

▲ 链接：

https://www.science.org/doi/10.1126/science.abl4881

▲ 摘要：

地球的生物多样性和人类社会面临着污染、自然资源过度消耗、城市化、人口结构变化、社会和经济不平等以及栖息地丧失等问题，其中许多问题因气候变化而加剧。

研究组回顾了气候、生物多样性和社会之间的联系，并制定了可持续发展的路线图。这些措施包括将升温限制在1.5℃以内，有效保护和恢复30%至50%的陆地、淡水和海洋“景观”上的功能性生态系统。

研究组设想一个相互关联的受保护和共享空间（包括集约利用的空间）的马赛克策略，以加强自我维持的生物多样性、人与自然适应和减缓气候变化的能力，以及自然对人类的贡献。促进人类、生态系统和地球健康相互关联以实现一个宜居的未来，迫切需要通过从地方到全球各级相互关联的机构、治理和社会系统大胆地实施变革性政策干预措施。

▲ Abstract：

Earth’s biodiversity and human societies face pollution, overconsumption of natural resources, urbanization, demographic shifts, social and economic inequalities, and habitat loss, many of which are exacerbated by climate change. Here, we review links among climate, biodiversity, and society and develop a roadmap toward sustainability. These include limiting warming to 1.5°C and effectively conserving and restoring functional ecosystems on 30 to 50% of land, freshwater, and ocean “scapes.” We envision a mosaic of interconnected protected and shared spaces, including intensively used spaces, to strengthen self-sustaining biodiversity, the capacity of people and nature to adapt to and mitigate climate change, and nature’s contributions to people. Fostering interlinked human, ecosystem, and planetary health for a livable future urgently requires bold implementation of transformative policy interventions through interconnected institutions, governance, and social systems from local to global levels.

▲ 作者：PAULO DE MARCO JR., RODRIGO A. DE SOUZA, ANDRÉ F. A. ANDRADE, SARA VILLÉN-PÉREZ, CAROLINE CORRÊA NÓBREGA, LUIZA MOTTA CAMPELLO, ET AL.

▲ 链接：

https://www.science.org/doi/10.1126/science.abq7768

▲ 摘要：

在私人土地内划出保护区可能是增强生物多样性友好型景观的关键。这种保护策略在巴西塞拉多等公共土地保护不力的高度受威胁地区应当特别有效。巴西的《原生植被保护法》已在私有财产中包括了预留区域，但尚未评估该策略与保护的相关性。

研究组评估了私人土地是否有益于塞拉多地区的生物多样性。塞拉多是全球生物多样性保护的重点地区，也是粮食生产的主要地区，土地使用冲突往往与保护目标不一致。分析结果确定私人保护区可容纳多达14.5%的渐危脊椎动物物种范围，考虑到剩余原生栖息地的分布，这一比例增至25%。

此外，私人保护区的空间扩展使大量物种受益。私人保护区的生态恢复将提高这种保护系统的效益，特别是在塞拉多东南部，那里的一个大型经济中心遭遇了威胁热点。

▲ Abstract：

Areas set aside for conservation within private lands may be key to enhancing biodiversity-friendly landscapes. This conservation strategy should be especially effective in highly threatened regions that are poorly protected by public lands, such as the Brazilian Cerrado. Brazil’s Native Vegetation Protection Law has included set-aside areas within private properties, but their relevance to conservation has not been evaluated. We assess whether private lands are contributing to biodiversity in the Cerrado, a global biodiversity conservation priority and major region for food production, where land use conflicts are often at odds with conservation objectives. We determined that private protected areas accommodate up to 14.5% of threatened vertebrate species ranges, which increases to 25% when considering the distribution of remaining native habitat. Moreover, the spatial spread of private protected areas benefits a large number of species. Ecological restoration of private protected lands would improve the benefits of this protection system, especially in the Southeastern Cerrado, where a large economic hub meets a threat hotspot.

动物学Zoology

▲ 作者：TOMOS POTTER, JEFF ARENDT, RONALD D. BASSAR, BETH WATSON, PAUL BENTZEN, JOSEPH TRAVIS, ET AL.

▲ 链接：

https://www.science.org/doi/10.1126/science.ade5671

▲ 摘要：

当雌性偏好具有罕见表型的配偶时，性选择可以维持而非耗尽遗传变异。然而，对于为什么这种广泛且经常观察到的偏好会进化并持续存在，人们尚未达成共识。

研究组使用跨越10代的系谱，探讨了特立尼达孔雀鱼自然种群中雌性偏好罕见雄性颜色模式的适应性后果。结果证明了(i)一种罕见的雄性生殖优势，(ii)与罕见雄性交配的雌性通过与儿子交配成功获得间接的适应性优势，以及(iii)雌性通过其“性感儿子”积累的适应性优势在表型变得普通的孙子身上消失了。

与主流理论相反，研究组证明雌性偏好可通过间接选择来维持。

▲ Abstract：

When females prefer mates with rare phenotypes, sexual selection can maintain rather than deplete genetic variation. However, there is no consensus on why this widespread and frequently observed preference might evolve and persist. We examine the fitness consequences of female preference for rare male color patterns in a natural population of Trinidadian guppies, using a pedigree that spans 10 generations. We demonstrate (i) a rare male reproductive advantage, (ii) that females that mate with rare males gain an indirect fitness advantage through the mating success of their sons, and (iii) the fitness benefit that females accrue through their “sexy sons” evaporates for their grandsons as their phenotype becomes common. Counter to prevailing theory, we show that female preference can be maintained through indirect selection.