中國向衛星傳送了首個“無法破解”的信息

Chinese scientists have sent the first quantum transmission from earth to an orbiting satellite, marking another key step in the creation of an “unhackable” global communications network.

中國科學家實現了從地面向在軌衛星的首次量子通信，向建立“無法破解”的全球通信網絡又邁進了關鍵一步。

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，科學期刊《自然》(Nature)發表了潘建偉帶領的研究團隊的實驗總結，他們在總結中表示，這些通信是在中國中西部的地面站和去年發射的一顆衛星之間進行的，傳輸距離長達1400公里。

“Previous [quantum] teleportation experiments between distant locations were limited to a distance of the order of 100km,” the scientists wrote.

這些科學家寫道：“以前，長距離(量子)傳送實驗的距離上限是100公里級。”

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.

與能被暗中竊聽的傳統通信不同，任何人嘗試竊聽量子通信都會產生可被量子通信網絡用戶察覺的干擾。

“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.”

該研究團隊成員、安徽合肥中國科學技術大學教授彭承志表示：“中國現在是量子通信技術的全球領跑者，并正積極與來自奧地利、德國和意大利的該領域科學家合作。中國將在未來5年引領量子空間競賽。”

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.

上海紐約大學(New York University Shanghai)量子物理學家蒂姆•伯恩斯(Tim Byrnes)說，這一結果“真的很了不起”。他指出，在中國的這些成功實驗——包括6月份從太空向地面的一次傳送——之前，量子通信的最長傳輸距離為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.

量子通信在地面網絡上的發展一直受到地球大氣中顆粒物的阻礙。據彭承志介紹，沿北京與上海之間的光纜進行量子通信將需要30多個中轉站。他說：“我們需要在每個站解碼信息并重新加密。”

As a result, quantum physicists have turned their attention to space-based networks.

因此，量子物理學家把注意力轉向了天基網絡。

“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.”

“這些實驗表明，你可以通過進入太空來真正克服這個問題，”伯恩斯說，“原因很簡單——太空是真空狀態的，光可以不受阻礙地長距離行進。美國、歐洲和日本多年來一直在嘗試這樣做。”

The $100m Micius satellite involved in the experiments was successfully launched in August 2016. It is named after an ancient Chinese philosopher and scientist.

這些實驗所涉及的耗資1億美元的“墨子號”(Micius)衛星于2016年8月成功發射。這顆衛星是以中國古代思想家、科學家墨子命名的。

Chinese scientists hope to launch a second quantum communications satellite by the summer of 2021.

中國科學家希望不晚于2021年夏發射第二顆量子通信衛星。

Ronald Hanson at the Technical University of Delft, in Holland, called Thursday’s announcement “a very important milestone” but noted that technical hurdles remained.

荷蘭代爾夫特理工大學(Technical University of Delft)教授羅納德•漢松(Ronald Hanson)稱，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術障礙。

“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.”

“我們距離建立全球量子網絡還很遙遠;這并不是缺失的最后一環，”漢松說，“這些衛星鏈路需要與本地量子處理器和存儲器連接起來——我們正努力建立這些系統。”

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.

中國科學家7月份表示，他們成功地在中國東部山東省濟南市部署了一個局地量子網絡。濟南的量子網絡將是正在構建的2000公里長的京滬量子網絡的關鍵一環。