China makes quantum leap in communication

On Thursday, the world's leading academic journal Nature published a paper from Chinese physicist Pan Jianwei's team on its groundbreaking achievement: The team has built a quantum communication network that is 4,600 kilometers long.

Pan is a professor at the University of Science and Technology of China in Hefei, capital of Anhui province.

Quantum communication technology is theoretically unhackable, as there is no way one can decrypt an encrypted message sent via quantum communication, because the encryption key is produced randomly and disappears thereafter.

It also includes an anti-bug feature. As the quantum encryption key is produced only once, if a third party intercepts it midway, the intended recipient will get a chaotic code alerting him.

US scientist Charles H. Bennett raised the idea of quantum teleportation in 1993, but applying the technology had long been a challenge, as Mencius, the world's first experimental quantum communication satellite was not launched into space until August 2016.

The challenge lies in sending the quantum communication and letting the recipient receive it. The scientist must, first, separate single photons from light and send them one at a time. Only Pan's team has been able to do so, the runner-up being a Japanese team, which can send only 100 million photons at a time.

Second, the photon traversing great lengths and reaching the recipient involves extreme precision. It is so small that any error in angle would send it to the wrong destination. Yuan Lanfeng, a teacher at the University of Science and Technology of China, likened it to throwing a coin into a cup on a high-speed moving train that is tens of kilometers away. In this case, one has to throw billions of coins, one after the other, and make sure each of them lands in the cup.

Pan's team alone has been able to do it, propelling China to pole position in quantum communication.