翻译 | 宗华
Science, 09 AUGUST 2019, VOL 365, ISSUE 6453
《科学》2019年8月9日，第365卷6453期
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Generation of multicomponent atomic Schrödinger cat states of up to 20 qubits
多组分原子薛定谔猫态的产生可达20个量子比特
▲ 作者：Chao Song, Kai Xu, Hekang Li, et al
▲ 链接：
https://science.sciencemag.org/content/365/6453/574
▲ 摘要：
多粒子纠缠态在量子信息科学中有着重要应用。
然而，在完全可控和可伸缩的量子平台上生成和验证多粒子纠缠仍是一项突出的挑战。
我们报告了在一台量子处理器上，一个18比特的格林伯格—霍恩—齐林格（GHZ）态和多达20比特的多组分原子薛定谔猫态的确定性生成。
该量子处理器拥有20个也称为人工原子、由总线谐振器连接的超导量子比特。
通过设计一个单轴扭曲的哈密顿量，量子比特系统一旦被初始化，就会相干地演化成多组分原子薛定谔猫态。
也就是说，原子相干态的叠加包括在预期的特定时间间隔内的GHZ态。
我们在固态平台上的方法应当不仅激发人们对探索量子多体系统基础物理学的兴趣，还会使得量子计量和量子信息处理的实际应用得到发展。
Multipartite entangled states are crucial for numerous applications in quantum information science. However, the generation and verification of multipartite entanglement on fully controllable and scalable quantum platforms remains an outstanding challenge. We report the deterministic generation of an 18-qubit Greenberger-Horne-Zeilinger (GHZ) state and multicomponent atomic Schrödinger cat states of up to 20 qubits on a quantum processor, which features 20 superconducting qubits, also referred to as artificial atoms, interconnected by a bus resonator. By engineering a one-axis twisting Hamiltonian, the system of qubits, once initialized, coherently evolves to multicomponent atomic Schrödinger cat states—that is, superpositions of atomic coherent states including the GHZ state—at specific time intervals as expected. Our approach on a solid-state platform should not only stimulate interest in exploring the fundamental physics of quantum many-body systems, but also enable the development of applications in practical quantum metrology and quantum information processing.
Generation and manipulation of Schrödinger cat states in Rydberg atom arrays
里德伯格原子阵列中薛定谔猫态的产生与操控
▲ 作者：A. Omran, H. Levine, A. Keesling, et al
▲ 链接：
https://science.sciencemag.org/content/365/6453/570
▲ 摘要：
量子纠缠涉及宏观上不同状态的相干叠加，这是量子理论最显著的特征之一。
然而，由于这种状态极其脆弱，因此实现量子纠缠具有挑战性。
我们利用一个基于中性原子阵列的可编程量子模拟器，通过里德伯格态介导的相互作用，展示了“薛定谔猫”态的创建。
该“薛定谔猫”属于格林伯格—霍恩—泽林格（GHZ）类型，最多有20个量子比特。
这种方法以设计能量谱为基础，采用多体系统的最优控制。
我们进一步展示了利用GHZ态将纠缠分布到阵列中较远位置的纠缠操作，为量子信息处理和量子计量奠定了重要基础。
Quantum entanglement involving coherent superpositions of macroscopically distinct states is among the most striking features of quantum theory, but its realization is challenging because such states are extremely fragile. Using a programmable quantum simulator based on neutral atom arrays with interactions mediated by Rydberg states, we demonstrate the creation of “Schrödinger cat” states of the Greenberger-Horne-Zeilinger (GHZ) type with up to 20 qubits. Our approach is based on engineering the energy spectrum and using optimal control of the many-body system. We further demonstrate entanglement manipulation by using GHZ states to distribute entanglement to distant sites in the array, establishing important ingredients for quantum information processing and quantum metrology.
A vicious cycle of β amyloid–dependent neuronal hyperactivation
依赖于β淀粉样蛋白的神经过度活跃的恶性循环
▲ 作者：Benedikt Zott, Manuel M. Simon, Wei Hong, et al
▲ 链接：
https://science.sciencemag.org/content/365/6453/559
▲ 摘要：
依赖于β淀粉样蛋白（Aβ）的神经过度活跃，被认为导致以早期阿尔茨海默氏症（AD）为特征的大脑回路功能障碍。
虽然支持这一假设的实验证据不断增加，但其潜在的病理机制尚未得到很好的理解。
在这项实验中,我们利用Aβ-淀粉样变性小鼠模型证明，过度活跃受到谷氨酸再摄取的抑制。
过度活跃现象发生在带有先前存在的基线活动的神经元内，而非活跃神经元通常抗拒Aβ介导的过度活跃。含有Aβ的AD大脑提取物和纯化的Aβ二聚体能维持这种恶性循环。
我们的研究结果表明了这样一种分子机制，即依赖于 Aβ的神经功能障碍可能在斑块形成前就开始活跃了。
β-amyloid (Aβ)–dependent neuronal hyperactivity is believed to contribute to the circuit dysfunction that characterizes the early stages of Alzheimer’s disease (AD). Although experimental evidence in support of this hypothesis continues to accrue, the underlying pathological mechanisms are not well understood. In this experiment, we used mouse models of Aβ-amyloidosis to show that hyperactivation is initiated by the suppression of glutamate reuptake. Hyperactivity occurred in neurons with preexisting baseline activity, whereas inactive neurons were generally resistant to Aβ-mediated hyperactivation. Aβ-containing AD brain extracts and purified Aβ dimers were able to sustain this vicious cycle. Our findings suggest a cellular mechanism of Aβ-dependent neuronal dysfunction that can be active before plaque formation.
Cortical layer–specific critical dynamics triggering perception
触发感知的皮层特异性临界动力学
▲ 作者：James H. Marshel, Yoon Seok Kim, Timothy A. Machado, et al
▲ 链接：
https://science.sciencemag.org/content/365/6453/eaaw5202
▲ 摘要：
感知经验可能来自哺乳动物新皮质的神经元活动模式。
我们利用红移通道视紫红质和多路复用多光子全息术，研究了视觉识别过程中的小鼠新皮质，并以毫秒的精度实现了对跨越大皮质体积的单个特定神经元的控制。
刺激一定数量的刺激物定向选择性神经元，可促进功能相关神经元的广泛招募。这一过程可以通过（但不需要）定向辨别任务学习得到增强。
定向选择性集群的光遗传靶向诱导了正确的行为识别。皮质层特异性动力学是明显的，因为突发性神经元活动从2/3层不对称地传播到第5层，而较小的第5层集群在诱导定向辨别行为上与较大的第2/3层集群一样有效。
在光遗传刺激后出现的种群动力学不仅正确地预测了行为，而且在皮层细胞分辨率上与视觉刺激的自然内部表征相似。
Perceptual experiences may arise from neuronal activity patterns in mammalian neocortex. We probed mouse neocortex during visual discrimination using a red-shifted channelrhodopsin (ChRmine, discovered through structure-guided genome mining) alongside multiplexed multiphoton-holography (MultiSLM), achieving control of individually specified neurons spanning large cortical volumes with millisecond precision. Stimulating a critical number of stimulus-orientation-selective neurons drove widespread recruitment of functionally related neurons, a process enhanced by (but not requiring) orientation-discrimination task learning. Optogenetic targeting of orientation-selective ensembles elicited correct behavioral discrimination. Cortical layer–specific dynamics were apparent, as emergent neuronal activity asymmetrically propagated from layer 2/3 to layer 5, and smaller layer 5 ensembles were as effective as larger layer 2/3 ensembles in eliciting orientation discrimination behavior. Population dynamics emerging after optogenetic stimulation both correctly predicted behavior and resembled natural internal representations of visual stimuli at cellular resolution over volumes of cortex.
A single fast radio burst localized to a massive galaxy at cosmological distance
一次定位于宇宙论距离上一个巨大星系的快速射电暴
▲ 作者：K. W. Bannister, A. T. Deller, C. Phillips, et al
▲ 链接：
https://science.sciencemag.org/content/365/6453/565
▲ 摘要：
快速射电暴（FRBs）是遥远的天文活动产生的短暂无线电辐射。有些已知是重复的，但大多数是单次爆发。
对不重复FRB的观测并未产生足够的位置精度，从而将其定位到一个单独的宿主星系。
我们报告了对单脉冲FRB 180924的干涉定位。我们将其定位于距红移0.3214处一个发光星系中心4千帕秒的位置。这次射电暴未被观测到重复发生。
射电暴及其宿主的性质与仅有的其他精确定位的FRB源有明显的不同。
沿着视线方向的融合电子柱密度与星系间介质的模型非常吻合，表明一些FRB是宇宙网重子组分的干净探测器。
Fast radio bursts (FRBs) are brief radio emissions from distant astronomical sources. Some are known to repeat, but most are single bursts. Nonrepeating FRB observations have had insufficient positional accuracy to localize them to an individual host galaxy. We report the interferometric localization of the single-pulse FRB 180924 to a position 4 kiloparsecs from the center of a luminous galaxy at redshift 0.3214. The burst has not been observed to repeat. The properties of the burst and its host are markedly different from those of the only other accurately localized FRB source. The integrated electron column density along the line of sight closely matches models of the intergalactic medium, indicating that some FRBs are clean probes of the baryonic component of the cosmic web.
Middle Stone Age foragers resided in high elevations of the glaciated Bale Mountains, Ethiopia
中石器时代采集者居住在埃塞俄比亚冰川覆盖的贝尔山脉高海拔地区
▲ 作者：Götz Ossendorf, Alexander R. Groos, Tobias Bromm, et al
▲ 链接：
https://science.sciencemag.org/content/365/6453/583
▲ 摘要：
对高山环境中早期人类居住点的研究提供了对人类生理、遗传和文化适应潜力的洞察。
虽然科学家最近发现了晚更新世甚至中更新世人类在青藏高原的存在，但对高海拔地区早期持续性人类定居点的性质和环境却知之甚少。
这里，我们报告了史前高海拔居住点的最早证据。
芬查·哈贝拉岩洞位于非洲最大的高山生态系统中，其历史可追溯到4.7万至3.1万年前。
在寒冷和冰川环境中可用的资源包括将一种地方性啮齿类动物作为主要的食物来源。
这为促进晚更新世狩猎—采集者占领这一地区起到了关键作用。
Studies of early human settlement in alpine environments provide insights into human physiological, genetic, and cultural adaptation potentials. Although Late and even Middle Pleistocene human presence has been recently documented on the Tibetan Plateau, little is known regarding the nature and context of early persistent human settlement in high elevations. Here, we report the earliest evidence of a prehistoric high-altitude residential site. Located in Africa’s largest alpine ecosystem, the repeated occupation of Fincha Habera rock shelter is dated to 47 to 31 thousand years ago. The available resources in cold and glaciated environments included the exploitation of an endemic rodent as a key food source, and this played a pivotal role in facilitating the occupation of this site by Late Pleistocene hunter-gatherers.
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