Recently, Professor Pan Jianwei, professor of University of Science and Technology of China, and colleagues Peng Chengzhi and Zhang Qiang, for the first time in the world, succeeded in achieving the quantum key distribution in the free space for a long time during the daytime (53km). The ground-based experiments were conducted on channel loss and noise level It validates the feasibility of constructing the quantum earth and inter-satellite quantum communication network based on quantum constellations in the future. International authoritative academic journal "Nature Photonics" recently published the results.
Quantum communication based on satellite platform is the most viable means to construct a global quantum communication network. The world's first quantum science experimental satellite "Mozi" has successfully implemented the first international quantum communication in the world, and has carried out large-scale quantum networks for the future And quantum communication experimental research laid the technical foundation. However, due to the influence of the sun noise, the Mozi satellites can only work at night, at least three days to complete the coverage of the ground stations worldwide.
In order to improve the practical level of satellite quantum communication, it is feasible to construct a quantum constellation consisting of many low-orbit satellites or high-orbit satellites to establish a global real-time quantum communication network. The construction of quantum constellation needs to break through two technical problems: First, the increase of communication distance will lead to increased link loss; second, the increase of satellite orbit will significantly increase the probability of being exposed to sunlight.
In order to suppress the sunlight background noise in the daytime, Pan Jianwei team has recently developed key technologies from three aspects: using 1550nm photons to optimize the optical system, reducing the noise by more than an order of magnitude, and developing the frequency upconversion single photon detection technology. The free space beam single Mode fiber coupling technology reduces noise by about four orders of magnitude. The team completed the quantum key distribution experiment in two days at a distance of 53 km from the sun in the daytime. The experimental results verify the feasibility of quantum key distribution in the background of the sun and the stars, and construct the quantum for the next step Constellation has laid a solid technical foundation.
The Review by Nature Reviewers commented that this achievement "addresses an important challenge in quantum key distribution in free space during the day," praising it as a "remarkable achievement."
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