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from the new-toys-are-all-made-in-china dept.
China has launched a satellite that will beam entangled photons to base stations on Earth:
China has successfully launched the world's first quantum-enabled satellite, state media said. It was carried on a rocket which blasted off from the Jiuquan Satellite Launch Centre in China's north west early on Tuesday. The satellite is named after the ancient Chinese scientist and philosopher Micius. The project tests a technology that could one day offer digital communication that is "hack-proof". But even if it succeeds, it is a long way off that goal, and there is some mind-bending physics to get past first.
The satellite will create pairs of so-called entangled photons - tiny sub-atomic particles of light whose properties are dependent on each other - beaming one half of each pair down to base stations in China and Austria. This special kind of laser has several curious properties, one of which is known as "the observer effect" - its quantum state cannot be observed without changing it. So, if the satellite were to encode an encryption key in that quantum state, any interception would be obvious. It would also change the key, making it useless.
(Score: 2) by Capt. Obvious on Wednesday August 17 2016, @06:04PM
A single photon is both a wave and a particle. However, the spotlight from a flashlight is not a single photon/single wave. It is made up of tons of photons. In fact, one of the big concerns in this system is that multiple photons are sent for any given bit. Each photon can only be "read" once and cannot be reproduced (oversimplification, reproduction is accurate 50% of the time). But if you send 2 photons with the same bit, and I intercept one of them, then I can read that one and you cannot detect it.
You can DOS this communication by taking a similar laser, pointing it at the receiver, and turning it on.