China Says It Has Developed a Quantum Radar That Can See Stealth Aircraft (digitaltrends.com)

An anonymous reader quotes a report from Digital Trends: At a recent air show in the city of Zhuhai, state-owned Chinese defense giant China Electronics Technology Group Corporation displayed what it claims to be a quantum radar that's able to detect even the stealthiest of stealth aircraft. The company claims to have been working on the technology for years, and to have tested it for the first time in 2015. In principle, a quantum radar functions like a regular radar -- only that instead of sending out a single beam of electromagnetic energy, it uses two split streams of entangled photons. Only one of these beams is sent out, but due to a quirk of quantum physics both streams will display the same changes, despite being potentially miles apart. As a result, by looking at the stream which remains back home it's possible to work out what has happened to the other beam. According to a brochure from the China Electronics Technology Group Corporation, the new quantum radar could "solve the traditional bottleneck [of] detection of low observable target detection, survival under electronic warfare conditions, [and] platform load limitations."

Comments

Bonus: it disproved Bell's theorem!

[goombah99]

Awesome, so this disproves bell's theorem and thus re-writes the laws of WM as we currently understand them.

Or at least the simplified description of this does. perhaps the real process is different.

Bell's entanglement experiment results in a rather cool result that even though one can have spooky actions at a distance, you cannot use it to transmit information. That is you can if you compare results at each end see that there was a measurement induced correlation in the photons but you can't determine this from the statistical distribution of measurements at either end by themselves.

Thus you can't possibly see the aircraft in the local beam due to changes in the remote beam.

Re:FTL Communications?

[Ungrounded Lightning]

If I'm reading this correctly, the exact same technology also enables faster-than-light communication.

Yep.

And if you can fling things around fast enough, faster-than-light communication enables future-to-past information transfer.

Bye, bye, grandma. (The grandfather paradox, female version, doesn't suffer from the "but it turns out grandpa was a cuckold" loophole.)

Fortunately for those of us who depend on causality for countinued existence, Bell's theorem says the radar doesn't really work.

(Though one that passes entangled photons past both sides of the plane, then measures their interference, might in principle detect the plane without exposing it to the photons. THAT one doesn't violate bell, lightspeed, or causality, but is pretty spooky.)