中国向卫星传送了首个“无法破解”的信息
中国科学家实现了从地面向在轨卫星的首次量子通信，向建立“无法破解”的全球通信网络又迈进了关键一步。
In a summary of their experiment published on Thursday in the scientific journal Nature, the team led by Pan Jianwei said the transmissions had travelled as far as 1,400km between base stations in central and western China and a satellite launched last year.
周四，科学期刊《自然》(Nature)发表了潘建伟带领的研究团队的实验总结，他们在总结中表示，这些通信是在中国中西部的地面站和去年发射的一颗卫星之间进行的，传输距离长达1400公里。
“Previous [quantum] teleportation experiments between distant locations were limited to a distance of the order of 100km,” the scientists wrote.
这些科学家写道：“以前，长距离(量子)传送实验的距离上限是100公里级。”
Unlike traditional communications, which can be tapped surreptitiously, anyone attempting to eavesdrop on a quantum communication creates a disturbance that can be detected by the network’s users.
与能被暗中窃听的传统通信不同，任何人尝试窃听量子通信都会产生可被量子通信网络用户察觉的干扰。
“China is now the world’s leader in quantum communication technologies and is actively co-operating with scientists from Austria, Germany and Italy in this field,” said Peng Chengzhi, a member of the research team and a professor at the University of Science and Technology in Hefei, Anhui province. “China will lead the quantum space race for the next five years.”
该研究团队成员、安徽合肥中国科学技术大学教授彭承志表示：“中国现在是量子通信技术的全球领跑者，并正积极与来自奥地利、德国和意大利的该领域科学家合作。中国将在未来5年引领量子空间竞赛。”
Tim Byrnes, a quantum physicist at New York University’s Shanghai campus, described the result as “truly remarkable”. He noted that before China’s successful experiments, including a transmission from space to Earth in June, the longest distance travelled by a quantum communication had been 143km.
上海纽约大学(New York University Shanghai)量子物理学家蒂姆•伯恩斯(Tim Byrnes)说，这一结果“真的很了不起”。他指出，在中国的这些成功实验——包括6月份从太空向地面的一次传送——之前，量子通信的最长传输距离为143公里。
Development of quantum communications on terrestrial networks has been impeded by the particles in the earth’s atmosphere. According to Prof Peng, a quantum communication along fibre-optic cables between Beijing and Shanghai would require more than 30 transfer stations. “We need to decode the information and re-encrypt it at each station,” he said.
量子通信在地面网络上的发展一直受到地球大气中颗粒物的阻碍。据彭承志介绍，沿北京与上海之间的光缆进行量子通信将需要30多个中转站。他说：“我们需要在每个站解码信息并重新加密。”
As a result, quantum physicists have turned their attention to space-based networks.
因此，量子物理学家把注意力转向了天基网络。
“These experiments show that you can really overcome this issue by going to space,” Mr Byrnes said. “The reason is simple — space is a vacuum and light can travel long distances unimpeded. The US, Europe and Japan have been trying to do this for years.”
“这些实验表明，你可以通过进入太空来真正克服这个问题，”伯恩斯说，“原因很简单——太空是真空状态的，光可以不受阻碍地长距离行进。美国、欧洲和日本多年来一直在尝试这样做。”
The $100m Micius satellite involved in the experiments was successfully launched in August 2016. It is named after an ancient Chinese philosopher and scientist.
这些实验所涉及的耗资1亿美元的“墨子号”(Micius)卫星于2016年8月成功发射。这颗卫星是以中国古代思想家、科学家墨子命名的。
Chinese scientists hope to launch a second quantum communications satellite by the summer of 2021.
中国科学家希望不晚于2021年夏发射第二颗量子通信卫星。
Ronald Hanson at the Technical University of Delft, in Holland, called Thursday’s announcement “a very important milestone” but noted that technical hurdles remained.
荷兰代尔夫特理工大学(Technical University of Delft)教授罗纳德•汉松(Ronald Hanson)称，周二宣布的消息是“非常重要的里程碑”，但他也指出仍存在一些技术障碍。
“We are still very far from making a global quantum network; this is not the last missing link,” Prof Hanson said. “Such satellite links would need to be linked with local quantum processors and memories — systems that we are working on.”
“我们距离建立全球量子网络还很遥远;这并不是缺失的最后一环，”汉松说，“这些卫星链路需要与本地量子处理器和存储器连接起来——我们正努力建立这些系统。”
In July, Chinese scientists said they had successfully deployed a local-area quantum network in Jinan, a city in eastern Shandong province. The Jinan network will also be a key link in a 2,000km quantum network being built between Beijing and Shanghai.
中国科学家7月份表示，他们成功地在中国东部山东省济南市部署了一个局地量子网络。济南的量子网络将是正在构建的2000公里长的京沪量子网络的关键一环。
