Scientists Measure Communication Between Quantum Entangled Atoms

Illustration for article titled Scientists Measure Communication Between Quantum Entangled Atoms

Einstein called it "spooky action at a distance:" one particle can instantaneously tell what another is doing without being anywhere near it. It's called quantum entanglement. And now NIST physicists have brought this effect to the real world.

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They demonstrated this effect using two "entangled" mechanical oscillators. (A mechanical oscillator can be anything from a pendulum to a watch spring to a guitar string. Here, it's vibrating atoms.) First, they separated two entangled atoms from each other. Then the scientists prodded one vibrating atom of the pair, and the other vibrating atom acted like it was being prodded too - despite being nowhere near the first one. The two seem to be almost telepathically communicating with each other, faster than the speed of light.

This isn't the first strange experiment in quantum entanglement. Entangled photon pairs have been used to take ghostly photos through opaque barriers. Entanglement is also a key part of the classic Schrodinger's Cat thought experiment. But this experiment shows that entanglement isn't limited to immeasurable scales: one day, quantum computers might harness this effect for instant, efficient processing.

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And there are even cooler implications from this experiment: In Philip Pullman's The Amber Spyglass, spies can instantaneously converse with their commanders by composing messages on a resonator entangled with a receiver worlds away. This recent experiment shows that Pullman's idea of large scale entanglement is theoretically possible, making faster-than-light communication more than just speculation.

via NIST Physicists Demonstrate Quantum Entanglement in Mechanical System [NIST]

Entangled Mechanical Oscillators [arXiv.org]

For further reading: "Ghost" Photographs Created via Quantum Entanglement

Image credit: John Jost and Jason Amini

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DISCUSSION

I don't understand: Isn't faster than light communication impossible because it automatically implies time travel? Then you have to throw out either relativity or causality; you can't keep both and have FTL communication. So, has relativity just been disproved? Or has it been proved that we live in a universe where causality doesn't quite work? Because either one would be a pretty ginormous change.

I was always under the impression that quantum entanglement is an interesting little quirk of physics, but can never be used for actual FTL communication - though I've never entirely understood why. But I do know that if you can send an FTL message, no matter what the exact circumstances, from *some* frame of reference, you'll always be sending that message from the future to the past. It would be possible to tell someone about an event that literally has not occurred for that person yet, and it would then be possible for this person to prevent the event from ever happening in the first place, thus preventing you from sending the message... So... How does this work?.. O_o