Major scientific breakthrough in quantum cryptographic communication

A major scientific breakthrough was announced recently, as satellite-based communication between two ground stations more than 1,120 kilometers apart was activated by entanglement-based quantum key distribution (QKD), thereby extending the distance without compromising security.

Undertaken by the world's first mobile quantum communication satellite, named Mozi or Micius after the Chinese philosopher, entangled photon pairs were distributed via bidirectional downlinks to two ground observatories in Delingha, Qinghai province and Nanshan, Urumqi, the capital of Xinjiang Uygur autonomous region.

The research was jointly conducted by Academician Pan Jianwei, his colleague Peng Chengzhi and Professor Yin Juan from the Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, in Hefei, Anhui province.

Also involved in the work were Professor Artur K. Ekert from the Mathematical Institute at the University of Oxford, as well as Academician Wang Jianyu and his research team from the Center for Excellence in Quantum Information at the Shanghai branch of the Chinese Academy of Sciences.

On June 15, the researchers published their paper titled "Entanglement-based secure quantum cryptography over 1,120 kilometers" in the magazine Nature, the world's leading multidisciplinary science journal.

One reviewer at Nature hailed the work as a "groundbreaking experiment, which takes a significant step towards establishing a global QKD network, and more generally, a quantum internet for quantum communication."

While speaking at a recent online press conference, Pan said: "Costs for making and launching satellites will plummet, allowing a solid foundation to be laid for the commercial use of satellite-based quantum communication in a much extensive way." According to Pan, this cutting-edge technology will reduce satellite payload weights from 10 tons to around 100 kilograms.

However, the physicist also stressed that the research has so far only been justified theoretically. It will require an additional six to seven years until the satellites are able to produce 1 billion pairs of entangled photons per second to ensure the implementation.

According to the paper's abstract, trusted relays have been adopted to extend the range of QKD from metropolitan areas to intercity and even intercontinental distances, although this does have the side effect of posing security challenges.