China achieves world’s first relayless entangled quantum key distribution over 1,120 km
It is the first time to ensure the security of satellite transmission keys through physical principles. This is also the first time in the world that entanglement-based quantum key distribution (QKD) of thousands of kilometers has been achieved.
A team of scientists led by Professor Pan Jianwei used Mozi, a quantum scientific experimental satellite, to achieve the distribution of quantum keys without relay entanglement over a long distance of 1120 kilometers.
This is the first time in the world.
Its achievements are mainly manifested in two aspects:
(1) It is the first time to ensure the security of satellite transmission keys through physical principles;
(2) This is also the first time in the world that entanglement-based quantum key distribution (QKD) of thousands of kilometers has been achieved.
The research results have been published in Nature magazine, entitled “Entanglement-based secure quantum cryptography over 1,120 kilometres”.
Quantum key distribution (QKD) is a secure method for sharing keys between remote users.
In theory, quantum communication provides an unconditional and secure communication method. But for practical application, there are two problems that need to be solved urgently, the security problem under real conditions and the long-distance transmission problem.
After more than 30 years of research in the scientific community, the maximum distance for generating quantum cryptographic links between stations on the earth is about 144 kilometers, and it can reach 500 kilometers in the laboratory.
If we want to achieve longer-distance quantum communication, we need to use information stations, such as satellites to act as a trusted relay for ground stations, to increase the length of the quantum link.
However, the security of the relay node needs human guarantee. Once the information station is hijacked or controlled by another party, there is a risk of information leakage.
In response, Pan’s team sought a new solution without the need for trusted relays. In this case, even if the satellite is hijacked or the device is controlled, the quantum key based on entanglement is still safe.