(AsiaTimes) A team of Chinese scientists have realized the satellite-based distribution of entangled photon pairs over 1,200 kilometers. The photon pairs were demonstrated to be still entangled after travelling long distances.
The distance is about 10 times further than the old, optic fiber-based quantum tech could do.
Experts said this represents a major milestone in building a practical global-scale, ultra-secure quantum internet, but the actual technology might still be years away. Gilles Brassard, one of the founders of quantum cryptography, said if the technology for secured, long distance quantum communication finally arrives, “this would achieve the Holy Grail that all cryptographers have been dreaming of for thousands of years.”
“QKD is theoretically highly secured. But in reality, imperfections in equipment such as photon sources and detectors may lead to security risks,” said Pan Jianwei, noted quantum physicist and lead scientist at Quantum Experiments at Space Scale (QUESS). To tackle these issues, Pan and his team tested a new QKD protocol method that uses satellites instead of ground-based relays.
They achieved this by using China’s quantum science satellite Micius to send a secret key at the rate of 0.12 bits per second between the ground stations at Delingha and Urumqi, separated by around 1,120 kilometers.

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