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NASA基于机器学习开发云检测的新方法 快报文章
地球科学快报,2020年第12期
作者:  刘燕飞
Microsoft Word(13Kb)  |  收藏  |  浏览/下载:381/0  |  提交时间:2020/06/24
NASA  Machine learning  Cloud detection  methods  
Coherent electrical control of a single high-spin nucleus in silicon 期刊论文
NATURE, 2020, 579 (7798) : 205-+
作者:  Dedoussi, Irene C.;  Eastham, Sebastian D.;  Monier, Erwan;  Barrett, Steven R. H.
收藏  |  浏览/下载:21/0  |  提交时间:2020/07/03

Nuclear spins are highly coherent quantum objects. In large ensembles, their control and detection via magnetic resonance is widely exploited, for example, in chemistry, medicine, materials science and mining. Nuclear spins also featured in early proposals for solid-state quantum computers(1) and demonstrations of quantum search(2) and factoring(3) algorithms. Scaling up such concepts requires controlling individual nuclei, which can be detected when coupled to an electron(4-6). However, the need to address the nuclei via oscillating magnetic fields complicates their integration in multi-spin nanoscale devices, because the field cannot be localized or screened. Control via electric fields would resolve this problem, but previous methods(7-9) relied on transducing electric signals into magnetic fields via the electron-nuclear hyperfine interaction, which severely affects nuclear coherence. Here we demonstrate the coherent quantum control of a single Sb-123 (spin-7/2) nucleus using localized electric fields produced within a silicon nanoelectronic device. The method exploits an idea proposed in 1961(10) but not previously realized experimentally with a single nucleus. Our results are quantitatively supported by a microscopic theoretical model that reveals how the purely electrical modulation of the nuclear electric quadrupole interaction results in coherent nuclear spin transitions that are uniquely addressable owing to lattice strain. The spin dephasing time, 0.1 seconds, is orders of magnitude longer than those obtained by methods that require a coupled electron spin to achieve electrical driving. These results show that high-spin quadrupolar nuclei could be deployed as chaotic models, strain sensors and hybrid spin-mechanical quantum systems using all-electrical controls. Integrating electrically controllable nuclei with quantum dots(11,12) could pave the way to scalable, nuclear- and electron-spin-based quantum computers in silicon that operate without the need for oscillating magnetic fields.


  
Fuzzy-logic detection and probability of hail exploiting short-range X-band weather radar 期刊论文
ATMOSPHERIC RESEARCH, 2018, 201: 17-33
作者:  Capozzi, Vincenzo;  Picciotti, Errico;  Mazzarella, Vincenzo;  Marzano, Frank Silvio;  Budillon, Giorgio
收藏  |  浏览/下载:17/0  |  提交时间:2019/04/09
Weather radar  X-band  Hailstorm  Detection methods  Data processing  Urban hydrometeorology