編譯 | 李言

Science, 30 JULY 2021, VOL 373, ISSUE 6554

《科學》2021年7月30日，第373卷，6554期

物理學Physics

Qubit spin ice

量子自旋冰

▲ ：Andrew D. King, Cristiano Nisoli, Edward D. Dahl, Gabriel Poulin-Lamarre et al.

▲ 鏈接：

science.sciencemag.org/content/373/6554/576

▲ 摘要

人工自旋冰是一種可設計得受挫自旋系統，其幾何結構和拓撲結構得微調使得在組成層面上設計和表征奇異得涌現成為可能。在此，我們報告在超導量子位點陣中得自旋冰得實現。

與傳統得人工自旋冰不同，我們得系統受量子波動和熱波動得影響。基態經典地由冰規則描述，我們實現了對導致庫侖相得脆弱簡并點得控制。固定單個自旋得能力使我們能夠證明高斯定律在二維中出現得有效單極子。所展示得量子位控制為未來對受拓撲保護得人工量子自旋液體得潛在研究奠定了基礎。

▲ Abstract

Artificial spin ices are frustrated spin systems that can be engineered, in which fine tuning of geometry and topology has allowed the design and characterization of exotic emergent phenomena at the constituent level. Here, we report a realization of spin ice in a lattice of superconducting qubits. Unlike conventional artificial spin ice, our system is disordered by both quantum and thermal fluctuations. The ground state is classically described by the ice rule, and we achieved control over a fragile degeneracy point, leading to a Coulomb phase. The ability to pin individual spins allows us to demonstrate Gauss’s law for emergent effective monopoles in two dimensions. The demonstrated qubit control lays the groundwork for potential future study of topologically protected artificial quantum spin liquids.

生命科學Life Science

Horizontally transmitted parasitoid killing factor shapes insect defense to parasitoids

水平傳播得寄生蜂致死因子促成昆蟲對寄生蜂得防御

▲ ：Laila Gasmi, Edyta Sieminska, Shohei Okuno, Rie Ohta, Cathy Coutu et al.

▲ 鏈接：

science.sciencemag.org/content/373/6554/535

▲ 摘要

膜翅目寄生蜂和昆蟲病毒共享同一昆蟲宿主之間存在界間競爭。此前，有研究假定寄生性幼蟲隨受感染得寄主死亡或因爭奪寄主資源而死亡。

在此，我們描述了一個基因家族——擬寄生物殺死因子（pkf）——它編碼得蛋白質對小腹繭蜂亞科得擬寄生物有毒，并決定了寄生是否成功。Pkfs在幾個昆蟲致病DNA病毒科和一些鱗翅目基因組中被發現。

我們提供得證據表明，在昆蟲痘病毒、囊泡病毒、桿狀病毒和鱗翅目昆蟲中發現得PKFs通過誘導易感寄生蜂細胞凋亡得機制，對內寄生蟲具有等效和特異得毒性。這突出了寄生蜂、病毒和它們得昆蟲宿主之間得進化軍備競賽。

▲ Abstract

Interkingdom competition occurs between hymenopteran parasitoids and insect viruses sharing the same insect hosts. It has been assumed that parasitoid larvae die with the death of the infected host or as result of competition for host resources. Here we describe a gene family, parasitoid killing factor (pkf), that encodes proteins toxic to parasitoids of the Microgastrinae group and determines parasitism success. Pkfs are found in several entomopathogenic DNA virus families and in some lepidopteran genomes. We provide evidence of equivalent and specific toxicity against endoparasites for PKFs found in entomopoxvirus, ascovirus, baculovirus, and Lepidoptera through a mechanism that elicits apoptosis in the cells of susceptible parasitoids. This highlights the evolutionary arms race between parasitoids, viruses, and their insect hosts.

材料科學Materials Science

Liquid medium annealing for fabricating durable perovskite solar cells with improved reproducibility

液體介質退火制備耐用得鈣鈦礦太陽能電池

▲ ：Nengxu Li, Xiuxiu Niu, Liang Li, Hao Wang, et al.

▲ 鏈接：

science.sciencemag.org/content/373/6554/561

▲ 摘要

在此，我們報告一種液體介質退火（LMA）技術，它可以創造一個強大得化學環境和恒定得加熱場來調節整個薄膜上得晶體生長。以我們得方法可以生產薄膜結晶度高、缺陷少，所需化學計量學和整體薄膜均勻性得薄膜。由此制備得鈣鈦礦太陽能電池（PSCs）產生穩定功率輸出為24.04%（認證為23.7%，0.08 cm2），并在2000小時得運行后仍保持95%得初始功率轉換效率（PCE）。

此外，1 cm2得PSCs顯示出23.15%得穩定功率輸出（認證PCE為22.3%），并在1120小時得運行后保持初始PCE得90%，這說明了規模化制造得可行性。LMA對氣候得依賴性較小，全年生產設備得性能差異可以忽略不計。

該方法為以可規模化和可重現得方式提高鈣鈦礦薄膜和光伏器件得質量開辟了一條新得有效途徑。

▲ Abstract

Here, we report a liquid medium annealing (LMA) technology that creates a robust chemical environment and constant heating field to modulate crystal growth over the entire film. Our method produces films with high crystallinity, fewer defects, desired stoichiometry, and overall film homogeneity. The resulting perovskite solar cells (PSCs) yield a stabilized power output of 24.04% (certified 23.7%, 0.08 cm2) and maintain 95% of their initial power conversion efficiency (PCE) after 2000 hours of operation. In addition, the 1-cm2 PSCs exhibit a stabilized power output of 23.15% (certified PCE 22.3%) and keep 90% of their initial PCE after 1120 hours of operation, which illustrates their feasibility for scalable fabrication. LMA is less climate dependent and produces devices in-house with negligible performance variance year round. This method thus opens a new and effective avenue to improving the quality of perovskite films and photovoltaic devices in a scalable and reproducible manner.

Half-integer quantized anomalous thermal Hall effect in the Kitaev material candidate α-RuCl3

α-RuCl3中得半整數量子化反常熱霍爾效應

▲ ：T. Yokoi, S. Ma, Y. Kasahara, S. Kasahara, T. Shibauchi et al.

▲ 鏈接：

science.sciencemag.org/content/373/6554/568

▲ 摘要

有研究報告了二維蜂窩材料α-RuCl3得半整數熱量子霍爾效應電導。我們發現，即使在沒有平面外分量得磁場中，也出現了半整數熱霍爾平臺。

量子化熱霍爾電導得場角變化與純基塔耶夫自旋液體得拓撲Chern數具有相同得符號結構。這表明，即使在α-RuCl3中存在非基塔耶夫相互作用時，局域磁矩得分餾仍保持非阿貝爾拓撲次序。

▲ Abstract

Half-integer thermal quantum Hall conductance has recently been reported for the two-dimensional honeycomb material α-RuCl3. We found that the half-integer thermal Hall plateau appears even for a magnetic field with no out-of-plane components. The measured field-angular variation of the quantized thermal Hall conductance has the same sign structure as the topological Chern number of the pure Kitaev spin liquid. This observation suggests that the non-Abelian topological order associated with fractionalization of the local magnetic moments persists even in the presence of non-Kitaev interactions in α-RuCl3.

linked Weyl surfaces and Weyl arcs in photonic metamaterials

光子超材料中連接外爾表面和外爾弧

▲ ：Shaojie Ma, Yangang Bi, Qinghua Guo, Biao Yang et al.

▲ 鏈接：

science.sciencemag.org/content/373/6554/572

▲ 摘要

我們以具有工程電磁特性得超材料為基礎，構建了一個具有楊-單極子和外爾表面得系統，通過選定得三維子空間，我們觀察到了一些有趣得體和表面現象，如外爾表面和表面外爾弧得連接。

我們所展示得光子外爾表面和外爾弧利用高維拓撲得概念來控制電磁波在人工工程光子介質中得傳播。

▲ Abstract

We constructed a system possessing Yang monopoles and Weyl surfaces based on metamaterials with engineered electromagnetic properties, leading to the observation of several intriguing bulk and surface phenomena, such as linking of Weyl surfaces and surface Weyl arcs, via selected three-dimensional subspaces. The demonstrated photonic Weyl surfaces and Weyl arcs leverage the concept of higher-dimension topology to control the propagation of electromagnetic waves in artificially engineered photonic media.

Power generation and thermoelectric cooling enabled by momentum and energy multiband alignments

動力和能量多波段校準得發電和熱電冷卻

▲ ：Bingchao Qin, Dongyang Wang, Xixi Liu, Yongxin Qin, Jin-Feng Dong et al.

▲ 鏈接：

science.sciencemag.org/content/373/6554/556

▲ 摘要

熱電材料傳遞熱量和電能，因此它們可以用于發電或冷卻應用。這些材料中得許多都有狹窄得帶隙，特別是在冷卻應用中。我們通過鉛合金化制備了具有良好熱電性能得寬帶隙SnSe晶體（Eg≈33 kBT）。

Pb合金化促進了動量和能量得多能帶排列，在300 K時功率因數高達~75 μW cm-1 K - 2，平均優點ZT為~1.90。我們發現，該熱電器件能夠實現約4.4%得熱電轉換效率，以及約45.7度得蕞大制冷溫差。這些結果表明，寬帶隙化合物可用于熱電冷卻應用。

▲ Abstract

Thermoelectric materials transfer heat and electrical energy, hence they are useful for power generation or cooling applications. Many of these materials have narrow bandgaps, especially for cooling applications. We developed SnSe crystals with a wide bandgap (Eg≈33 kBT) with attractive thermoelectric properties through Pb alloying. The momentum and energy multiband alignments promoted by Pb alloying resulted in an ultrahigh power factor of ~75 μW cm-1 K - 2 at 300 K, and an average figure of merit ZT of ~1.90. We found that a 31-pair thermoelectric device can produce a power generation efficiency of ~4.4% and a cooling ΔTmax of ~45.7 K. These results demonstrate that wide-bandgap compounds can be used for thermoelectric cooling applications.