Nature, 16 May 2024, Volume 629 Issue 8012

《天然》2024年5月16日，第629卷，8012期

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量子物理学Quantum Physics

Probing entanglement in a 2D hard-core Bose–Hubbard lattice

二维硬核玻色—哈伯德晶格中的纠缠探测

▲ 作者：Amir H. Karamlou, Ilan T. Rosen et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07325-z

▲ 摘要：

在此，我们利用可控的4×4超导量子比特阵列来摹拟二维硬核玻色—哈伯德晶格。我们经由过程同时驱动所有晶格格位发生叠加态，并在其多体能谱中提取相干长度和纠缠熵。我们不雅察到光谱中间状况的体积律纠缠缩放，和在其边沿四周最先的面积定律缩放的交叉。

▲ Abstract：

Here we use a controllable 4 × 4 array of superconducting qubits to emulate a 2D hard-core Bose–Hubbard (HCBH) lattice. We generate superposition states by simultaneously driving all lattice sites and extract correlation lengths and entanglement entropy across its many-body energy spectrum. We observe volume-law entanglement scaling for states at the centre of the spectrum and a crossover to the onset of area-law scaling near its edges.

Fusion of deterministically generated photonic graph states

肯定性生成光子图态的融会

▲ 作者：Philip Thomas, Leonardo Ruscio, Olivier Morin Gerhard Rempe

▲ 链接：

https://www.nature.com/articles/s41586-024-07357-5

▲ 摘要：

虽然如贝尔态或线性簇态如许的小型图态已可以或许经由过程光子发生，但为了知足日趋增加的量子计较和量子收集利用需求，需要可编程的方式将这些小范围的纠缠态融会成更壮大的状况。

在此，我们经由过程利用包括两个零丁可寻址原子的光学谐振器来实现这一方针。环形和树形图态最多有8个量子比特，其名称反应纠缠拓扑，有用地融会了单个原子的光子态。

核聚变进程自己在两个原子之间利用一个腔辅助门。我们的手艺原则上可以扩大到更年夜数目的量子比特，而且成为将来量子互联网中无记忆量子中继器的决议性一步。

▲ Abstract：

Small graph states such as Bell or linear cluster states have been produced with photons, but the proposed quantum-computing and quantum-networking applications require fusion of such states into larger and more powerful states in a programmable fashion. Here we achieve this goal by using an optical resonator containing two individually addressable atoms. Ring and tree graph states with up to eight qubits, with the names reflecting the entanglement topology, are e开云体育appfficiently fused from the photonic states emitted by the individual atoms. The fusion process itself uses a cavity-assisted gate between the two atoms. Our technique is, in principle, scalable to even larger numbers of qubits and is the decisive step towards, for instance, a memory-less quantum repeater in a future quantum internet.

建筑学uArchitecture

Arresting failure propagation in buildings through collapse isolation

经由过程隔离崩塌禁止建筑物内粉碎舒展

▲ 作者：Nirvan Makoond, Andri Setiawan, Manuel Buitrago Jose M. Adam

▲ 链接：

https://www.nature.com/articles/s41586-024-07268-5

▲ 摘要：

在此，我们提出了一种原始的设计方式来禁止首要初始故障后的崩塌舒展。当倾圮最先时，该方式确保在整体不变的最要害构成部门掉效之前，特定要素会掉效。如许，布局系统就割裂成分歧的部门，并在其舒展不成避免时隔离崩塌。

经由过程对一个专门建造的全尺寸建筑物进行尝试测试，我们证实了该方式的有用性。我们还证实，假如依照当前体例的建议增添毗连性，那末年夜的初始故障将致使测试建筑的完全崩塌。我们提出的方式可觉得更具弹性的建筑成立最后一道防地。

▲ Abstract：

Here we present an original design approach to arrest collapse propagation after major initial failures. When a collapse initiates, the approach ensures that specific elements fail before the failure of the most critical components for global stability. The structural system thus separates into different parts and isolates collapse when its propagation would otherwise be inevitable. The effectiveness of the approach is proved through unique experimental tests on a purposely built full-scale building. We also demonstrate that large initial failures would lead to total collapse of the test building if increased connectivity was implemented as recommended by present guidelines. Our proposed approach enables incorporating a last line of defence for more resilient buildings.

能源科学Energy Science

A high-density and high-confinement tokamak plasma regime for fusion energy

可用在聚变能的高密度高束缚托卡马克等离子体

▲ 作者：S. Ding, A. M. Garofalo et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07313-3

▲ 摘要：

在此，我们陈述了不变的托卡马克等离子体的演示，其线平均密度比格林沃尔德密度高约20%，能量束缚质量比尺度高束缚模式晋升约50%，这是经由过程操纵高极向—β情形下高密度梯度对湍流输运的加强按捺实现的。

另外，我们的尝试成果显示了极低边沿瞬态扰动，与高归一化密度和束缚焦点的积分。我们陈述的运行机制撑持世界上很多聚变反映堆设计的要害要求，并为经济可行的聚变能源斥地了潜伏的路子。

▲ Abstract：

Here we report the demonstration of stable tokamak plasmas with a line-averaged density approximately 20% above the Greenwald density and an energy confinement quality of approximately 50% better than the standard high-confinement mode, which was realized by taking advantage of the enhanced suppression of turbulent transport granted by high density-gradients in the high-poloidal-beta scenario. Furthermore, our experimental results show an integration of very low edge transient perturbations with the high normalized density and confinement core. The operating regime we report supports some critical requirements in many fusion reactor designs all over the world and opens a potential avenue to an operating point for producing economically attractive fusion energy.

地球科学Earth science

One-third of Southern Ocean productivity is supported by dust deposition

沙尘沉积支持了南年夜洋三分之一的出产力

▲ 作者：Jakob Weis, Zanna Chase et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07366-4

▲ 摘要：

在此，我们连系了11年来自立生物地球化学的海洋剖面浮标的硝酸盐不雅测数据和南半球的尘埃摹拟，以经验推导出铁有限的南年夜洋中尘埃—铁沉积与年净群落产量（ANCP）之间的关系。操纵这一信息，我们肯定了今朝和末次盛冰期（LGM）时代南年夜洋中上层终年无冰地域对尘埃—铁的生物响应。

我们估量尘埃—铁此刻撑持这南年夜洋年净群落产量的33%±15%。在末次盛冰期时代，当沙尘沉降比今天高5—40倍时，沙尘对南年夜洋年净群落产量的进献要年夜很多，估量为64%±13%。

▲ Abstract：

Here we combined 11 years of nitrate observations from autonomous biogeochemical ocean profiling floats with a Southern Hemisphere dust simulation to empirically derive the relationship between dust-iron deposition and annual net community production (ANCP) in the iron-limited Southern Ocean. Using this relationship, we determined the biological response to dust-iron in the pelagic perennially ice-free Southern Ocean at present and during the last glacial maximum (LGM). We estimate that dust-iron now supports 33% ± 15% of Southern Ocean ANCP. During the LGM, when dust deposition was 5–40-fold higher than today, the contribution of dust to Southern Ocean ANCP was much greater, estimated at 64% ± 13%.

生物学Biology

Sleep pressure modulates single-neuron synapse number in zebrafish

睡眠压力调理斑马鱼单神经元突触数

▲ 作者：Anya Suppermpool, Declan G. Lyons, Elizabeth Broom Jason Rihel

▲ 链接：

https://www.nature.com/articles/s41586-024-07367-3

▲ 摘要：

在此，经由过程频频对斑马鱼幼体睡眠—苏醒状况下单个神经元上的所有兴奋性突触进行成像，我们发此刻苏醒时代会取得突触，在睡眠时代以神经元亚型依靠的体例丢掉突触。

但是，在长时候苏醒后，与高睡眠压力相干的睡眠时代突触损掉最年夜，而在未受干扰的夜晚后半段，突触损掉最低。与此相反，在低睡眠压力期间，药物致使的睡眠不足以激发突触丢掉，除非腺苷程度被提高，去甲肾上腺素能张力被按捺。

由此我们认为，睡眠依靠的突触损掉是由单个神经元程度的睡眠压力调理的，其实不是所有的睡眠期间都能告竣突触稳态的功能。

▲ Abstract：

Here, by repeatedly imaging all excitatory synapses on single neurons across sleep–wake states of zebrafish larvae, we show that synapses are gained during periods of wake (either spontaneous or forced) and lost during sleep in a neuron-subtype-dependent manner. However, synapse loss is greatest during sleep associated with high sleep pressure after prolonged wakefulness, and lowest in the latter half of an undisrupted night. Conversely, sleep induced pharmacologically during periods of low sleep pressure is insufficient to trigger synapse loss unless adenosine levels are boosted while noradrenergic tone is inhibited. We conclude that sleep-dependent synapse loss is regulated by sleep pressure at the level of the single neuron and that not all sleep periods are equally capable of fulfilling the functions of synaptic homeostasis.

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