南极洲■《自然》一周论文导读丨人类细胞体节时钟的体外特征( 二 ) |白垩纪|地质|土伦|

目前， 40°S以南海域仅有7.1%已受到正式保护，其中AES总量占29% 。研究人员认为，需要建立和定期修订海洋生态系统保护网络，以便长期减轻对南部海洋生态系统日益增加的压力。
▲ Abstract
Southern Ocean ecosystems are under pressure from resource exploitation and climate change. Mitigation requires the identification and protection of Areas of Ecological Significance (AESs), which have so far not been determined at the ocean-basin scale. Here, using assemblage-level tracking of marine predators, we identify AESs for this globally important region and assess current threats and protection levels. Integration of more than 4,000 tracks from 17 bird and mammal species reveals AESs around sub-Antarctic islands in the Atlantic and Indian Oceans and over the Antarctic continental shelf. Fishing pressure is disproportionately concentrated inside AESs, and climate change over the next century is predicted to impose pressure on these areas, particularly around the Antarctic continent. At present, 7.1% of the ocean south of 40°S is under formal protection, including 29% of the total AESs. The establishment and regular revision of networks of protection that encompass AESs are needed to provide long-term mitigation of growing pressures on Southern Ocean ecosystems.
物理学 Physics
Experimental demonstration of memory-enhanced quantum communication
存储增强量子通信的实验演示
▲ 作者：M. K. Bhaskar、R. Riedinger、M. D. Lukin ， et al.
▲ 链接：
https://www.nature.com/articles/s41586-020-2103-5
▲ 摘要
在量子科学和工程中，远距离传输量子信息的能力是至关重要的。虽然一些量子通讯的应用，例如安全的量子密钥分发，已经成功部署，但它们的范围目前受到光子损耗的限制，不能使用简单测量和重复策略来扩展，而不损害无条件的安全性。
在这里，研究人员使用一个单一的固态自旋存储器集成在一个纳米光子钻石谐振器上，以实现异步光子Bell态测量，这是量子中继器的关键组成部分。
在一个原理证明的实验中，研究人员演示了高保真操作，有效地使量子通信的速率超过了理想的损失等效直接传输方法。这些结果代表了迈向实用量子中继器和大规模量子网络的关键一步。
▲ Abstract
The ability to communicate quantum information over long distances is of central importance in quantum science and engineering. Although some applications of quantum communication such as secure quantum key distribution are already being successfully deployed, their range is currently limited by photon losses and cannot be extended using straightforward measure-and-repeat strategies without compromising unconditional security. Alternatively, quantum repeaters, which utilize intermediate quantum memory nodes and error correction techniques, can extend the range of quantum channels. However, their implementation remains an outstanding challenge, requiring a combination of efficient and high-fidelity quantum memories, gate operations, and measurements. Here we use a single solid-state spin memory integrated in a nanophotonic diamond resonator to implement asynchronous photonic Bell-state measurements, which are a key component of quantum repeaters. In a proof-of-principle experiment, we demonstrate high-fidelity operation that effectively enables quantum communication at a rate that surpasses the ideal loss-equivalent direct-transmission method while operating at megahertz clock speeds. These results represent a crucial step towards practical quantum repeaters and large-scale quantum networks.