The satellite transmits a signal around the globe using quantum entanglement, or creating pairs of photons that exist in the same quantum state. Even at great distances, the two photons will be identical to each other, allowing one to communicate via entangled photons as long as both sides possess the same secret key to access them. In this case, the key was a polarized proton, or a subatomic piece of light with tweaked magnetism and spin on its axis.
Scientists have referred to the process as “teleporting” a photon through space — making something here appear suddenly there.
It’s theoretically impossible to hack that transmission. Anyone who intercepted information would observe and therefore alter the key according to the laws of quantum mechanics. Both sides would immediately be alerted to an interloper, too.
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Long-distance quantum communication has been difficult to achieve beyond more than 200 miles because of interference — a beam of light can only go so far on the ground, the Chinese scientists wrote. The satellite solves that problem by transmitting mostly over empty space.
“The exchange of quantum encrypted information over inter-continental distances confirms the potential of quantum communication technologies as opened up by fundamental research,” said Zeilinger. "This is a very important step towards a world-wide and secure quantum internet."
The Chinese Academy said the progress showed that the world’s most populous country was on track to becoming a tech leader.
“China has made great progress in the advanced manufacturing industries, such as aerospace, nuclear power, and high-speed [rail], which will constitute its enterprises' core competitiveness in the global market,” said the Academy press release, citing China Daily, an English-language state-owned newspaper. “And if China maintains the momentum of this progress, the shift from ‘Made in China’ to ‘Designed in China’ will only be a matter of time.”
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