乐鱼《自然》（20231012出版）一周论文导读—新闻—科学网

天文学Astronomy

A planetary collision afterglow and transit of the resultant debris cloud

行星碰撞的余晖以及孕育发生的碎片云凌日

▲ 作者：Matthew Kenworthy, Simon Lock et al.

▲ 链接：

https://www.nature.com/articles/s41586-023-06573-9

▲ 择要：

于此，咱们陈诉对于约莫3亿年前的年青类太阳恒星ASASSN-21qj的综合不雅测：与黑体温度1000开尔文一致的红外增亮以及连续约1000天的恒星的4%的光度，与连续约500天的繁杂以及深度、波长依靠的光学日蚀举行部门堆叠。

这次日蚀最先在红外增亮后的2.5年，这象征着它的轨道周期至少为2.5年。这些不雅测成果与2颗品质为地球数倍至数十倍的系生手星于间隔中央恒星2-16个天文单元之处发生碰撞后的环境是一致的。

如许的撞击孕育发生了一个炙热的、高度延长的撞击后遗址，其孕育发生的亮度可以注释红外不雅测成果。撞击碎片后的凌日，被轨道运动分化，致使主星日蚀孕育发生。

▲ Abstract：

Here we report combined observations of the young (about 300 million years old), solar-like star ASASSN-21qj: an infrared brightening consistent with a blackbody temperature of 1,000 Kelvin and a luminosity that is 4 percent that of the star lasting for about 1,000 days, partially overlapping in time with a complex and deep, wavelength-dependent optical eclipse that lasted for about 500 days. The optical eclipse started 2.5 years after the infrared brightening, implying an orbital period of at least that duration. These observations are consistent with a collision between two exoplanets of several to tens of Earth masses at 2-16 astronomical units from the central star. Such an impact produces a hot, highly extended post-impact remnant with sufficient luminosity to explain the infrared observations. Transit of the impact debris, sheared by orbital motion into a long cloud, causes the subsequent complex eclipse of the host star.

A super-massive Neptune-sized planet

一颗海王星巨细的超年夜品质行星

▲ 作者：Luca Naponiello, Luigi Mancini et al.

▲ 链接：

https://www.nature.com/articles/s41586-023-06499-2

▲ 择要：

这里咱们展示了凌日行星TOI-1853 b的不雅测成果，它的半径为地球半径的3.46 0.08倍，每一1.24天绕一颗矮星运转一次。这颗行星的品质是地球的73.2 2.7倍，险些是今朝已经知的海王星巨细行星的2倍，密度为9.7 0.8克每一立方厘米。

这些数字让咱们以为TOI-1853 b于海王星戈壁之中，这象征着重元素盘踞了它的年夜部门品质。TOI-1853 b的特征给传统的行星造成以及演化理论提出了一个难题。它多是频频原行星碰撞孕育发生的成果，也多是一颗最初高离心率的行星向其母恒星迁徙后的终极状况。

▲ Abstract：

Here we show observations of the transiting planet TOI-1853 b, which has a radius of 3.46 0.08 Earth radii and orbits a dwarf star every 1.24 days. This planet has a mass of 73.2 2.7 Earth masses, almost twice that of any other Neptune-sized planet known so far, and a density of 9.7 0.8 grams per cubic centimetre. These values place TOI-1853 b in the middle of the Neptunian desert and imply that heavy elements dominate its mass. The properties of TOI-1853 b present a puzzle for conventional theories of planetary formation and evolution, and could be the result of several proto-planet collisions or the final state of an initially high-eccentricity planet that migrated closer to its parent star.

物理学Physics

State estimation of a physical system with unknown governing equations

对于未知节制方程物理体系的状况评估

▲ 作者：Kevin Course Prasanth B. Nair

▲ 链接：

https://www.nature.com/articles/s41586-023-06574-8

▲ 择要：

于此，咱们提出了一种用马尔科夫决议计划历程举行随机变分推理的再参数化技巧。这类技巧可使用类似贝叶斯要领举行状况预计，此中节制体系随时间蜕变的方程部门或者彻底未知。

与传统的状况评估技能比拟，咱们的要领从类似贝叶斯的角度同时进修数学模子中的缺掉项以及状况评估。这一成长使状况预计要领可以或许运用在今朝被证实没法解决的问题。末了，虽然我这次专一在状况评估，但这里所做的随机变分推理的进展合用在呆板进修中更广泛的问题。

▲ Abstract：

Here we present a reparametrization trick for stochastic variational inference with Markov Gaussian processes that enables an approximate Bayesian approach for state estimation in which the equations governing how the system evolves over time are partially or completely unknown. In contrast to classical state-estimation techniques, our method learns the missing terms in the mathematical model and a state estimate simultaneously from an approximate Bayesian perspective. This development enables the application of state-estimation methods to problems that have so far proved to be beyond reach. Finally, although we focus on state estimation, the advancements to stochastic variational inference made here are applicable to a broader class of problems in machine learning.

High-fidelity parallel entangling gates on a neutral-atom quantum computer

中性原子量子计较机上的高保真平行纠缠门

▲ 作者：Simon J. Evered, Dolev Bluvstein et al.

▲ 链接：

https://www.nature.com/articles/s41586-023-06481-y

▲ 择要：

于此，咱们陈诉以99.5%的保真度于多达60个原子上并行实现的双量子比特纠缠门，这一数值跨越了外貌码的纠错阈值。咱们的要领使用的是基在最优节制的倏地单脉冲门，同时哄骗原子暗态来削减散射，并革新里德堡引发以及原子冷却。

咱们使用基在反复门运用的几种要领对于保真度举行基准测试，表征物理偏差源并概述将来的革新。末了，咱们归纳综合了设计触及更大批子比特的纠缠门的要领，而且经由过程实现低偏差的三量子比特门举行展示。

▲ Abstract：

Here we report the realization of two-qubit entangling gates with 99.5% fidelity on up to 60 atoms in parallel, surpassing the surface-code threshold for error correction. Our method uses fast, single-pulse gates based on optimal control, atomic dark states to reduce scattering and improvements to Rydberg excitation and atom cooling. We benchmark fidelity using several methods based on repeated gate applications, characterize the physical error sources and outline future improvements. Finally, we generalize our method to design entangling gates involving a higher number of qubits, which we demonstrate by realizing low-error three-qubit gates.

High-fidelity gates and mid-circuit erasure conversion in an atomic qubit

原子量子比特中的高保真门以及中电路擦除了转换

▲ 作者：Shuo Ma, Genyue Liu et al.

▲ 链接：

https://www.nature.com/articles/s41586-023-06438-1

▲ 择要：

于此，咱们展示了一个于171Yb中哄骗原子核自旋的长命命亚稳态的新中性原子量子位。较长的相关时间以及对于里德堡态的倏地引发使患上保真度别离为0.9990(1)以及0.980(1)的单量子比特门以及双量子比特门成为可能。主要的是，年夜部门门过错会致使量子比特子空间向基态的衰减。

经由过程对于这些过错举行倏地的中电路检测，咱们将它们转换为擦除了过错；于检测历程中，计较空间中残剩量子位的引诱过错几率小在10 5。咱们的研究成立了亚稳态171Yb，一个可以实现容错量子计较的、有远景的平台。

▲ Abstract：

Here we demonstrate a new neutral atom qubit using the nuclear spin of a long-lived metastable state in 171Yb. The long coherence time and fast excitation to the Rydberg state allow one- and two-qubit gates with fidelities of 0.9990(1) and 0.980(1), respectively. Importantly, a large fraction of all gate errors result in decays out of the qubit subspace to the ground state. By performing fast, mid-circuit detection of these errors, we con����APPvert them into erasure errors; during detection, the induced error probability on qubits remaining in the computational space is less than 10 5. This work establishes metastable 171Yb as a promising platform for realizing fault-tolerant quantum computing.

生态学Ecology

Ongoing declines for the world s amphibians in the face of emerging threats

世界两栖植物数目因新威逼连续降落

▲ 作者：Jennifer A. Luedtke, Janice Chanson et al.

▲ 链接：

https://www.nature.com/articles/s41586-023-06578-4

▲ 择要：

于此，咱们评估8011种列入国际天然掩护同盟濒危物种红色名录的物种后，陈诉第二次全世界两栖植物评估的成果。咱们发明两栖植物是最受威逼的脊椎植物（40.7%的物种于全世界遭到威逼）。最新的红色名录指数显示，全世界两栖植物的状态正于恶化，尤为是蝾螈以及新热带地域的物种。

1980年至2004年间，91%的状态恶化是由疾病以及栖息地损失酿成的。今朝天气变迁的影响愈来愈使人担心，自2004年以来已经经形成39%的状态恶化。其次是栖息地损失（37%）。只管物种恢复的迹象促令人们当即采纳掩护步履，但仍火急需要增长投入以旋转今朝的趋向。

▲ Abstract：

Here we report the findings of the second Global Amphibian Assessment, evaluating 8,011 species for the International Union for Conservation of Nature Red List of Threatened Species. We find that amphibians are the most threatened vertebrate class (40.7% of species are globally threatened). The updated Red List Index shows that the status of amphibians is deteriorating globally, particularly for salamanders and in the Neotropics. Disease and habitat loss drove 91% of status deteriorations between 1980 and 2004. Ongoing and projected climate change effects are now of increasing concern, driving 39% of status deteriorations since 2004, followed by habitat loss (37%). Although signs of species recoveries incentivize i妹妹ediate conservation action, scaled-up investment is urgently needed to reverse the current trends.

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