Nature, Volume 617,Issue 7960, 11 May 2023
《自然》第617卷，7960期，2023年5月11日
物理学Physics
CConcurrent self-assembly of RGB microLEDs for next-generation displays
用于下一代显示器的微型LED的并发自组装
▲ 作者：Wonjae Chang, Jungsub Kim, Myoungsoo Kim, Min Woo Lee, Chung Hyun Lim, Gunho Kim, Sunghyun Hwang, Jeeyoung Chang, Young Hwan Min, Kiseong Jeon, Soohyun Kim, Yoon-Ho Choi & Jeong Soo Lee
▲ 链接：
https://www.nature.com/articles/s41586-023-05889-w
▲ 摘要：
与有机发光二极管（OLED）相比，微型LED显示器具有寿命长、亮度高等优点，作为下一代显示器备受关注。因此，微型发光二极管技术正在商业化应用于诸如数字标牌之类的大屏幕显示，同时也在积极开展研发项目，用于增强现实、柔性显示和生物成像等其他应用。然而，需要克服转移技术方面的重大障碍，即高吞吐量、高良率和高达第10代（2,940 × 3,370 mm2）玻璃尺寸的生产可扩展性，以便微型LED能够进入主流产品市场，并与液晶显示器和OLED显示器竞争。本文提出了一种新的基于流体自组装（FSA）技术的转移方法，称为磁力辅助介电泳自组装技术（MDSAT）。
该方法结合了磁力和介电泳（DEP）力，在15分钟内实现了99.99%的红、绿、蓝（RGB）LED同时转移率。通过在微型LED中嵌入镍（一种铁磁性材料），通过磁铁控制其运动，并通过施加以受体孔为中心的局部DEP力，这些微型LED被有效地捕获并组装在受体位点。此外，通过微型LED和受体之间的形状匹配，证明了RGB LED的并发组装。最后，制作了一个发光面板，显示了无损伤的转移特性和均匀的RGB电致发光发射，证明了MDSAT方法是一种优秀的转移技术候选，可用于主流商业产品的大批量生产。
▲ Abstract：
MicroLED displays have been in the spotlight as the next-generation displays owing to their various advantages, including long lifetime and high brightness compared with organic light-emitting diode (OLED) displays. As a result, microLED technology is being commercialized for large-screen displays such as digital signage and active R&D programmes are being carried out for other applications, such as augmented reality, flexible displays and biological imaging5. However, substantial obstacles in transfer technology, namely, high throughput, high yield and production scalability up to Generation 10+ (2,940× 3,370 mm2) glass sizes, need to be overcome so that microLEDs can enter mainstream product markets and compete with liquid-crystal displays and OLED displays. Here we present a new transfer method based on fluidic self-assembly (FSA) technology, named magnetic-force-assisted dielectrophoretic self-assembly technology (MDSAT), which combines magnetic and dielectrophoresis (DEP) forces to achieve a simultaneous red, green and blue (RGB) LED transfer yield of 99.99% within 15 min. By embedding nickel, a ferromagnetic material, in the microLEDs, their movements were controlled by using magnets, and by applying localized DEP force centred around the receptor holes, these microLEDs were effectively captured and assembled in the receptor site. Furthermore, concurrent assembly of RGB LEDs were demonstrated through shape matching between microLEDs and receptors. Finally, a light-emitting panel was fabricated, showing damage-free transfer characteristics and uniform RGB electroluminescence emission, demonstrating our MDSAT method to be an excellent transfer technology candidate for high-volume production of mainstream commercial products.
Tunable electron–flexural phonon interaction in graphene heterostructures
石墨烯异质结构中可调谐电子-弯曲声子相互作用
▲ 作者：Mir Mohammad Sadeghi, Yajie Huang, Chao Lian, Feliciano Giustino, Emanuel Tutuc, Allan H. MacDonald, Takashi Taniguchi, Kenji Watanabe & Li Shi
▲ 链接：
https://www.nature.com/articles/s41586-023-05879-y
▲ 摘要：
特殊的电子-声子相互作用特性支撑了石墨烯异质结构中观察到的超高迁移率、电子流体力学、超导性和超流动性。电子热导率与电导率和温度的乘积之间的洛伦兹比提供了对电子-声子相互作用的深入了解，这是过去石墨烯测量无法实现的。
作者发现简并石墨烯在60开尔文附近有一个不寻常的洛伦兹比峰，并且随着迁移率的增加峰的大小减小。当结合多体电子-声子自能的从头计算和分析模型时，这一实验观察表明，石墨烯异质结构中反射对称性的破坏可以放宽限制性选择规则，允许准弹性电子与奇数个弯曲声子耦合。在低温流体力学和120开尔文以上非弹性电子-声子散射之间的中间温度下，洛伦兹比向索默菲尔德极限增加。
与过去忽视二维材料中弯曲声子对传输的贡献的做法相反，这项工作表明，可调谐的电子-弯曲声子耦合可以提供一个在原子尺度上控制量子物质的手柄，例如在奇妙角扭曲双层石墨烯中，低能激发可以介导平带电子的库珀配对。
▲ Abstract：
Peculiar electron–phonon interaction characteristics underpin the ultrahigh mobility, electron hydrodynamics, superconductivity and superfluidity observed in graphene heterostructures. The Lorenz ratio between the electronic thermal conductivity and the product of the electrical conductivity and temperature provides insight into electron–phonon interactions that is inaccessible to past graphene measurements. Here we show an unusual Lorenz ratio peak in degenerate graphene near 60 kelvin and decreased peak magnitude with increased mobility. When combined with ab initio calculations of the many-body electron–phonon self-energy and analytical models, this experimental observation reveals that broken reflection symmetry in graphene heterostructures can relax a restrictive selection rule to allow quasielastic electron coupling with an odd number of flexural phonons, contributing to the increase of the Lorenz ratio towards the Sommerfeld limit at an intermediate temperature sandwiched between the low-temperature hydrodynamic regime and the inelastic electron–phonon scattering regime above 120 kelvin. In contrast to past practices of neglecting the contributions of flexural phonons to transport in two-dimensional materials, this work suggests that tunable electron–flexural phonon couping can provide a handle to control quantum matter at the atomic scale, such as in magic-angle twisted bilayer graphene where low-energy excitations may mediate Cooper pairing of flat-band electrons.
Many-body cavity quantum electrodynamics with driven inhomogeneous emitters
驱动非均匀发射体的多体腔量子电动力学
▲ 作者：Mi Lei, Rikuto Fukumori, Jake Rochman, Bihui Zhu, Manuel Endres, Joonhee Choi & Andrei Faraon
▲ 链接：
https://www.nature.com/articles/s41586-023-05884-1
▲ 摘要：
耦合于光谐振器的量子发射体是探索腔量子电动力学（cQED）基本现象的典型系统，通常用于量子器件，如量子位、存储器和换能器。许多以前的实验cQED研究都集中在少数相同的发射器与弱外部驱动器相互作用的情况下，这样系统就可以用简单有效的模型来描述。
然而，受强驱动的无序多体量子系统的动力学尚未得到充分探索，尽管其在量子应用中的重要性和潜力。作者研究了高协同性的大型非均匀加宽固体发射体系综与纳米光子谐振腔在强激发下的行为。他们在腔反射光谱中发现了一个明显的集体诱导透明（CIT），这是由驱动的非均匀发射体和腔光子之间的相互作用引起的量子干涉和集体响应造成的。
此外，CIT窗口内的相干激发导致高度非线性的光学发射，从快速的超辐射到缓慢的亚辐射。多体cQED体系中的这些现象为实现慢光和频率参考提供了新机制，为固态超辐射激光器铺平了道路，并为基于系综的量子互连的发展提供了信息。
▲ Abstract：
Quantum emitters coupled to optical resonators are quintessential systems for exploring fundamental phenomena in cavity quantum electrodynamics (cQED) and are commonly used in quantum devices acting as qubits, memories and transducers. Many previous experimental cQED studies have focused on regimes in which a small number of identical emitters interact with a weak external drive, such that the system can be described with simple, effective models. However, the dynamics of a disordered, many-body quantum system subject to a strong drive have not been fully explored, despite its importance and potential in quantum applications. Here we study how a large, inhomogeneously broadened ensemble of solid-state emitters coupled with high cooperativity to a nanophotonic resonator behaves under strong excitation. We discover a sharp, collectively induced transparency (CIT) in the cavity reflection spectrum, resulting from quantum interference and collective response induced by the interplay between driven inhomogeneous emitters and cavity photons. Furthermore, coherent excitation within the CIT window leads to highly nonlinear optical emission, spanning from fast superradiance to slow subradiance. These phenomena in the many-body cQED regime enable new mechanisms for achieving slow light and frequency referencing, pave a way towards solid-state superradiant lasers and inform the development of ensemble-based quantum interconnects.
Loophole-free Bell inequality violation with superconducting circuits
超导电路的无漏洞贝尔不等式破坏
▲ 作者：Simon Storz, Josua Sch?r, Anatoly Kulikov, Paul Magnard, Philipp Kurpiers, Janis Lütolf, Theo Walter, Adrian Copetudo, Kevin Reuer, Abdulkadir Akin, Jean-Claude Besse, Mihai Gabureac, Graham J. Norris, Andrés Rosario, Ferran Martin, José Martinez, Waldimar Amaya, Morgan W. Mitchell, Carlos Abellan, Jean-Daniel Bancal, Nicolas Sangouard, Baptiste Royer, Alexandre Blais & Andreas Wallraff
▲ 链接：
https://www.nature.com/articles/s41586-023-05885-0
▲ 摘要：
叠加、纠缠和非定域性构成了量子物理的基本特征。量子物理学不遵循局部因果关系原理的事实，可以在对空间分离、纠缠的量子系统进行的贝尔测试中得到实验证明。贝尔测试被广泛认为是量子物理学的试金石，在过去的50年里，人们已经在广泛的量子系统中进行了探索，但直到最近，没有所谓漏洞的实验才取得了成功。这类实验已经在氮空位中心、光子和中性原子的自旋中进行过。
研究者展示了超导电路对贝尔不等式的无漏洞违反，这是实现量子计算技术的主要竞争者。为了评估CHSH贝尔不等式，他们确定地纠缠一对量子位，并沿着随机选择的碱基在通过跨越30米距离的低温链路连接的量子位上进行快速高保真测量。
通过对100多万次试验的评估，研究者发现平均S值为2.0747±0.0033，P值小于10−108，违反贝尔不等式。该研究表明，非局域性是超导电路实现量子信息技术的一种可行的新资源，在量子通信、量子计算和基础物理中具有潜在的应用前景。
▲ Abstract：
Superposition, entanglement and non-locality constitute fundamental features of quantum physics. The fact that quantum physics does not follow the principle of local causality can be experimentally demonstrated in Bell tests performed on pairs of spatially separated, entangled quantum systems. Although Bell tests, which are widely regarded as a litmus test of quantum physics, have been explored using a broad range of quantum systems over the past 50 years, only relatively recently have experiments free of so-called loopholes succeeded. Such experiments have been performed with spins in nitrogen–vacancy centres, optical photons and neutral atoms10. Here we demonstrate a loophole-free violation of Bell’s inequality with superconducting circuits, which are a prime contender for realizing quantum computing technology. To evaluate a Clauser–Horne–Shimony–Holt-type Bell inequality, we deterministically entangle a pair of qubits and perform fast and high-fidelity measurements along randomly chosen bases on the qubits connected through a cryogenic link spanning a distance of 30?metres. Evaluating more than 1million experimental trials, we find an average S value of 2.0747±0.0033, violating Bell’s inequality with a P value smaller than 10−108. Our work demonstrates that non-locality is a viable new resource in quantum information technology realized with superconducting circuits with potential applications in quantum communication, quantum computing and fundamental physics.
生态和气候Ecology & Climate
Indian Ocean salinity build-up primes deglacial ocean circulation recovery
印度洋盐度增加加速冰川消融后海洋环流恢复
▲ 作者：Sophie Nuber, James W. B. Rae, Xu Zhang, Morten B. Andersen, Matthew D. Dumont, Huw T. Mithan, Yuchen Sun, Bas de Boer, Ian R. Hall & Stephen Barker
▲ 链接：
https://www.nature.com/articles/s41586-023-05866-3
▲ 摘要：
印度洋通过阿古拉斯渗漏为北大西洋深水对流点提供了盐源，并可能因此推动海洋翻转环流的变化。然而，在过去的冰期循环中，印度洋和阿古拉斯渗漏水的含盐量变化以及这可能如何影响环流所知甚少。研究表明，冰期印度洋表层盐收支与现代明显不同，对海平面变化有动态响应。印度洋表面盐度在冰川强化期间增加，在冰川极大期达到峰值。
他们发现，这是由于冰川海平面下降导致印度尼西亚群岛的陆地快速暴露，作者认为与相对新鲜的印度尼西亚通流水流入印度洋的减少有关。利用气候模式结果，研究者发现冰川印度洋盐度在消冰期间通过Agulhas渗漏释放，可以直接影响大西洋经向翻转环流和全球气候。
▲ Abstract：
The Indian Ocean provides a source of salt for North Atlantic deep-water convection sites, via the Agulhas Leakage, and may thus drive changes in the ocean’s overturning circulation. However, little is known about the salt content variability of Indian Ocean and Agulhas Leakage waters during past glacial cycles and how this may influence circulation. Here we show that the glacial Indian Ocean surface salt budget was notably different from the modern, responding dynamically to changes in sea level. Indian Ocean surface salinity increased during glacial intensification, peaking in glacial maxima. We find that this is due to rapid land exposure in the Indonesian archipelago induced by glacial sea-level lowering, and we suggest a mechanistic link via reduced input of relatively fresh Indonesian Throughflow waters into the Indian Ocean. Using climate model results, we show that the release of this glacial Indian Ocean salinity via the Agulhas Leakage during deglaciation can directly impact the Atlantic Meridional Overturning Circulation and global climate.
High-throughput printing of combinatorial materials from aerosols
气溶胶组合材料的高通量打印
▲ 作者：Minxiang Zeng, Yipu Du, Qiang Jiang, Nicholas Kempf, Chen Wei, Miles V. Bimrose, A. N. M. Tanvir, Hengrui Xu, Jiahao Chen, Dylan J. Kirsch, Joshua Martin, Brian C. Wyatt, Tatsunori Hayashi, Mortaza Saeidi-Javash, Hirotaka Sakaue, Babak Anasori, Lihua Jin, Michael D. McMurtrey & Yanliang Zhang
▲ 链接：
https://www.nature.com/articles/s41586-023-05898-9
▲ 摘要：
新材料的开发及其成分和微观结构的优化对于清洁能源和环境可持续性等下一代技术至关重要。然而，材料的发现和优化一直是一个令人沮丧的缓慢过程。爱迪生式的试错过程耗时且资源效率低下，特别是与巨大的材料设计空间相比。
虽然传统的组合沉积方法可以生成材料库，但这些方法受到材料选择有限和无法利用纳米材料合成的重大突破的影响。作者报告了一种高通量组合打印方法，能够在微尺度空间分辨率下制造具有成分梯度的材料。在气溶胶相的原位混合和印刷允许在飞行中瞬时调整各种材料的混合比例，这是使用液-液或固-固相原料的传统多材料印刷无法实现的重要特征。
他们展示了多种高通量印刷策略及其在组合掺杂、功能分级和化学反应中的应用，使掺杂硫族化合物和具有梯度特性的组合分级材料的材料探索成为可能。将增材制造自上而下的设计自由与自下而上对局部材料成分的控制相结合的能力，有望开发出传统制造方法无法实现的复杂材料。
▲ Abstract：
The development of new materials and their compositional and microstructural optimization are essential in regard to next-generation technologies such as clean energy and environmental sustainability. However, materials discovery and optimization have been a frustratingly slow process. The Edisonian trial-and-error process is time consuming and resource inefficient, particularly when contrasted with vast materials design spaces. Whereas traditional combinatorial deposition methods can generate material libraries, these suffer from limited material options and inability to leverage major breakthroughs in nanomaterial synthesis. Here we report a high-throughput combinatorial printing method capable of fabricating materials with compositional gradients at microscale spatial resolution. In situ mixing and printing in the aerosol phase allows instantaneous tuning of the mixing ratio of a broad range of materials on the fly, which is an important feature unobtainable in conventional multimaterials printing using feedstocks in liquid–liquid or solid–solid phases. We demonstrate a variety of high-throughput printing strategies and applications in combinatorial doping, functional grading and chemical reaction, enabling materials exploration of doped chalcogenides and compositionally graded materials with gradient properties. The ability to combine the top-down design freedom of additive manufacturing with bottom-up control over local material compositions promises the development of compositionally complex materials inaccessible via conventional manufacturing approaches.
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