翻译 | 李言
Nature,16 April 2020, Volume 580 Issue 7803
《天然》2020年4月16日，第580卷，7803期
量子物理学
Quantum Physics
Operation of a silicon quantum processor unit cell above one kelvin
量子核算渠道运转温度提至一开尔文以上
▲作者：C. H. Yang, R. C. C. Leon, J. C. C. Hwang, A. Saraiva, T. Tanttu, W. Huang, et al.
▲ 链接：
https://retion versus that subducted from the Earth’s surface is unclear. Here we show that the mantle may have retained remnants of such primordial nitrogen. We use the rare15N15Nisotopologue ofN2as a new tracer of air contamination in volcanic gas effusions. By constraining air contamination in gases from Iceland, Eifel(Germany) and Yellowstone (USA), we derive estimates of mantleδ15N(the fractional difference in15N/14Nfrom air),N2/36ArandN2/3He. Our results show that negativeδ15Nvalues observed in gases, previously regarded as indicating a mantle origin for nitrogen, in fact represent dominantly air-derivedN2that experienced15N/14Nfractionation in hydrothermal systems. We find that whereas the Yellowstone plume hasδ15Nvalues substantially greater than that of the convective mantle, resembling surface components, itsN2/36ArandN2/3Heratios are indistinguishable from those of the convective mantle. This observation raises the possibility that the plume hosts a primordial component.
古人类学Paleoanthropology
Dating the skull from Broken Hill, Zambia, and its position in human evolution
来自赞比亚布罗肯希尔的头骨断代，以及它在人类进化史中的方位
▲作者：Rainer Grün, Alistair Pike, Frank McDermott, Stephen Eggins, Graham Mortimer, et al.
▲ 链接：
https://essible using accelerator-produced beams as established by the Tokai-to-Kamioka (T2K) and NOvA experiments. Until now, the value ofδCPhas not been substantially constrained by neutrino oscillation experiments. Here we report a measurement using long-baseline neutrino and antineutrino oscillations observed by the T2K experiment that shows a large increase in the neutrino oscillation probability, excluding values ofδCPthat result in a large increase in the observed antineutrino oscillation probability at three standard deviations (3σ). The 3σ confidence interval forδCP, which is cyclic and repeats every 2π, is [ 3.41, 0.03] for the so-called normal mass ordering and [ 2.54, 0.32] for the inverted mass ordering. Our results indicate CP violation in leptons and our method enables sensitive searches for matter–antimatter asymmetry in neutrino oscillations using accelerator-produced neutrino beams. Future measurements with larger datasets will test whether leptonic CP violation is larger than the CP violation in quarks.
Submicrosecond entangling gate between trapped ions via Rydberg interaction
经过里德堡相互作用在捕获离子之间的亚微秒羁绊门
▲作者：Chi Zhang, Fabian Pokorny, Weibin Li, Gerard Higgins, Andreas P schl, Igor Lesanovsky & Markus Hennrich
▲ 链接：
https:///articles/s41586-020-2152-9
▲ 摘要
在大体系中，在比相干时刻短得多的时刻标准上发生量子羁绊是强壮的量子模仿和核算的要害。
在极性分子和里德堡原子体系中的强偶极-偶极相互作用答应更快的羁绊门，然而与被捕获的离子比较，安稳的独立状况束缚需求在这些体系中被证明。
在此，咱们调集了各种办法的优势：咱们陈述一个具有700纳秒极时刻的双离子羁绊门，它使用了被捕获的里德堡离子之间的强偶极相互作用，来发生一个精确度78%的贝尔态。
咱们确认了栅差错的来历，并对试验可到达的参数进行了总差错小于0.2%的猜测。此外，咱们还猜测，在100个离子的大离子晶体中，剩余耦合到运动模态会导致大约10-4的栅差错。这供给了一种办法以充沛加快和增大捕获离子量子核算机和模仿器的规模。
▲ Abstract
Generating quantum entanglement in large systems on timescales much shorter than the coherence time is key to powerful quantum simulation and computation. The strong dipole–dipole interactions in polar molecule and Rydberg atom systems allow much faster entangling gates, yet stable state-independent confinement comparable with trapped ions needs to be demonstrated in these systems. Here we combine the benefits of these approaches: we report a two-ion entangling gate with 700-nanosecond gate time that uses the strong dipolar interaction between trapped Rydberg ions, which we use to produce a Bell state with 78 per cent fidelity. The sources of gate error are identified and a total error of less than 0.2 per cent is predicted for experimentally achievable parameters. Furthermore, we predict that residual coupling to motional modes contributes an approximate gate error of10-4in a large ion crystal of 100 ions. This provides a way to speed up and scale up trapped-ion quantum computers and simulators substantially.
材料科学Material Science
Performance-limiting nanoscale trap clusters at grain junctions in halide perovskites
在卤化物钙钛矿晶粒交界处的约束器材功能的纳米标准圈套簇
▲作者：Tiarnan A. S. Doherty, Andrew J. Winchester, Stuart Macpherson, etal.
▲ 链接：
https:///articles/s41586-020-2184-1
▲ 摘要
尽管点缺陷一般只在钙钛矿带隙中发生不影响功能的浅层电子态，但钙钛矿器材在带隙深处仍有许多状况，它们能够捕获载流子并使其从头结合。这些深圈套态导致了光致发光的部分改变，约束了器材的功能。
在此，咱们使用光电子显微镜使得卤化物钙钛矿薄膜中的圈套散布成像。在光致发光功率较差的区域内，咱们观察到的不是一个相对均匀的散布，而是离散的纳米标准圈套簇。
经过将显微镜丈量与扫描电子剖析技能相结合，咱们发现这些圈套簇出现在晶体学上和组成上天壤之别的实体之间的界面上。
最终，经过生成光激起载流子捕获进程的时刻分辩光发射序列，咱们提醒了一个空穴捕获特性，其动力学遭到空穴分散到局域圈套簇的约束。
▲ Abstract
Although point defects often induce only shallow electronic states in the perovskite bandgap that do not affect performance, perovskite devices still have many states deep within the bandgap that trap charge carriers and cause them to recombine non-radiatively. These deep trap states thus induce local variations in photoluminescence and limit the device performance. Here we use photoemission electron microscopy to image the trap distribution in state-of-the-art halideperovskite films. Instead of a relatively uniform distribution within regions of poor photoluminescence efficiency, we observe discrete, nanoscale trap clusters. By correlating microscopy measurements with scanning electronanalytical techniques, we find that these trap clusters appear at the interfaces between crystallographically and compositionally distinct entities. Finally, by generating time-resolved photoemission sequences of the photo-excited carrier trapping process, we reveal a hole-trapping character with the kinetics limited by diffusion of holes to the local trap clusters.
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