It looked like just another conference call. A panel of suited men sat at a table, large white name tags and water bottles before them. The man in the center, illuminated by fluorescent lights, spoke to a camera in front of him.
“It is such a privilege and thrill to witness this historical moment with you all,” said Chunli Bai, the president of the Chinese Academy of Sciences, on that afternoon last September. His image streamed live to another table of suited men more than 4,500 miles away and six hours behind, at the Austrian Academy of Sciences in Vienna.
The Austrian delegation responded to Bai with their own pleasantries. The mics, cameras, and screens made for a seemingly ordinary—maybe even boring—meeting-by-telepresence. But behind the scenes, physicists were encrypting the videostream using arguably the most secure technology in existence. Bai and his colleagues were participating on the first-ever intercontinental, quantum-encrypted video conference.
And on Friday, the Chinese and Austrian researchers who engineered the call published how they did it in Physical Review Letters. Led by physicist Jian-Wei Pan of the University of Science and Technology of China, the team relied on networks of optical fiber, a handful of encryption algorithms, and a $100 million satellite that China launched in 2016—the only one specifically designed for quantum cryptography. “They’ve demonstrated a full infrastructure,” says Caleb Christensen, the chief scientist at MagiQ Technologies, which makes quantum cryptography systems that connect a small number of users. “They’ve connected all the links. Nobody’s done that with [quantum encryption] ever.”
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