Quantum Secure Communication with QKD
In the previous post, the highlights of the Micius experiments were described in brief. In this post, we delve into additional applications and further improvements in quantum secure communications.
The successful integration of the Micius satellite with a ground fiber QKD network stands as a significant achievement in the domain of quantum communication. Through enhancements in operational frequency, telescope dimensions, and coupling efficiency of the ground station, coupled with the application of an optimized unbalanced basis selection protocol, the QKD key rate reached an impressive 47.8 kbps over a single orbit, with a maximum satellite-relayed QKD key of approximately 36 Mbit per week. To harness the mobility and adaptability of satellite-based QKD, the development of portable ground stations weighing under 100 kg, requiring minimal space, and rapid installation times has proven indispensable. These stations, when deployed on urban rooftops, facilitate space-to-ground QKD experiments using Micius.
However, challenges persist in the realm of satellite-based QKD applications. Micius, being a Low Earth Orbit (LEO) satellite, is constrained by a limited transmission window and ground coverage in each orbit. Operating mainly during night-time due to wavelength and solar background noise limitations, Micius primarily validated space-to-ground QKD feasibility rather than practical application. Efforts to overcome such challenges have led to innovations like daytime free-space QKD, circumventing sunlight scattering background noise by employing a 1550 nm wavelength light source and detector. Incorporating a narrow bandwidth grating filter and an ultra-low noise up-conversion single photon detector further reduced background noise and achieved a 20 bps key rate QKD.
For the realization of a comprehensive global space-to-ground quantum communication and QKD network, expansion in the number of satellites and orbit altitudes is necessary. The concept involves a quantum constellation integrating both Low Earth Orbit (LEO) and geosynchronous orbit (GEO) satellites. In 2022, the launch of the QKD nano-satellite Jinan-1, weighing only 1/6th of Micius, marked a significant step in this direction. This nano-satellite boasts an enhanced light source frequency, real-time post-processing, and key generation capabilities. Anticipations are high for future experiments and demonstrational quantum secure communication applications conducted by these nano-satellites and portable ground stations. In conclusion, these advancements underscore the continual progress in the field of quantum communication and the exciting prospects it holds for secure and efficient data transmission.
References —
- https://www.nature.com/articles/s41586-020-03093-8.pdf
- https://arxiv.org/pdf/2205.13828.pdf
- https://www.nature.com/articles/nphoton.2017.116.pdf
- https://news.satnews.com/2022/07/31/china-launches-new-satellite-in-important-step-towards-global-quantum-communications-network/
Note: This article is a part of my Womanium Online Quantum Media Project. Find out about it here .
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