Nature, 16 May 2024, Volume 629 Issue 8012

《天然》2024年5月16日，第629卷，8012期

?

量子物理学Quantum Physics

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

二维硬核博色—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

▲ 择要：

于此，咱们使用可控的4×4超导量子比特阵列来模仿二维硬核博色—哈伯德晶格。咱们经由过程同时驱动所有晶格格位孕育发生叠加态，并于其多体能谱中提取相干长度以及纠缠熵。咱们不雅察到光谱中央状况的体积律纠缠缩放，和于其边沿四周最先的面积定律缩放的交织。

▲ 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

确定性天生光子图态的交融

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

▲ 链接：

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

▲ 择要：

只管如贝尔态或者线性簇态如许的小型图态已经经可以或许经由过程光子孕育发生，但为了满意日趋增加的量子计较以及量子收集运用需求，需要可编程的要领将这些小范围的纠缠态交融成更强盛的状况。

于此，咱们经由过程使用包罗两个零丁可寻址原子的光学谐振器来实现这一方针。环形以及树形图态至多有8个量子比特，其名称反应纠缠拓扑，有用地交融了单个原子的光子态。

核聚变历程自己于两个原子之间使用一个腔辅助门。咱们的技能准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影象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 progra妹妹able 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 efficiently 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.

修建学uArchitecture

Arresting failure propagation in buildings through collapse isolation

经由过程断绝崩塌制止修建物内粉碎伸张

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

▲ 链接：

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

▲ 择要：

于此，咱们提出了一种原始的设计要领来制止重要初始妨碍后的崩塌伸张。当坍毁最先时，该要领确保于总体不变的最要害构成部门掉效以前，特定因素会掉效。如许，布局系统就破裂成差别的部门，并于其伸张不成防止时断绝崩塌。

经由过程对于一个专门制作的全尺寸修建物举行试验测试，咱们证实了该要领的有用性。咱们还证实，假如根据当前体式格局的提议增长毗连性，那末年夜的初始妨碍将致使测试修建的彻底崩塌。咱们提出的要领可认为更具弹性的修建成立末了一道防地。

▲ 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 reco妹妹ended 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约束托卡马克等离子体

▲ 作者：S. Ding, A. M. Garofalo et al.

▲ 链接：

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

▲ 择要：

于此，咱们陈诉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%，能量约束品质比尺度高约束模式晋升约50%，这是经由过程哄骗高极向—β情景下高密度梯度对于湍流输运的加强按捺实现的。

此外，咱们的试验成果显示了极低边沿瞬态扰动，与高归一化密度以及约束焦点的积分。咱们陈诉的运转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于的路子。

▲ 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

沙尘沉积支撑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

▲ 择要：

于此，咱们联合了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以及南半球的灰尘模仿，以经验推导出铁有限的南年夜洋中灰尘—铁沉积与年净群落产量（ANCP）之间的瓜葛。哄骗这一信息，咱们确定了今朝以及末次盛冰期（LGM）时期南年夜洋中上层常年无冰地域对于灰尘—铁的生物相应。

咱们预计灰尘—铁此刻撑持这南年夜洋年净群落产量的33%±15%。于末次盛冰期时期，当沙尘沉降比昨天高5—40倍时，沙尘对于南年夜洋年净群落产量的孝敬要年夜患上多，预计为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 co妹妹unity 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

睡眠压力调治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

▲ 择要：

于此，经由过程重复对于斑马鱼幼体睡眠—苏醒状况下单个神经元上的所有高兴性突触举行成像，咱们发明于苏醒时期会得到突触，于睡眠时期以神经元亚型依靠的体式格局遗失突触。

然而，于永劫间苏醒后，与高睡眠压力相干的睡眠时期突触丧失最年夜，而于未受滋扰的夜晚后半段，突触丧失最低。与此相反，于低睡眠压力期间，药物致使的睡眠有余以激发突触遗失，除了非腺苷程度被提高，去甲肾上腺素能张力被按捺。

由此咱们以为，睡眠依靠的突触丧失是由单个神经元程度的睡眠压力调治的，其实不是所有的睡眠期间都能告竣突触稳态的功效。

▲ 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.