New Record For Quantum Teleportation: About 100 Miles

Sub-space radio?

Scientists have set a record in sending information using the revolutionary technology of quantum teleportation - although Mr Spock may have to wait a little longer for a Scotty to beam him up with it.

A team of physicists have teleported data 143km from the Canary Island of La Palma to the neighbouring island of Tenerife, which is 10 times further than the previous attempt at teleportation through free space.

The scientists did it by exploiting the "spooky" and virtually unfathomable field of quantum entanglement - when the state of matter rather than the matter itself is sent from one place to another.

Tiny packets or particles of light called photons were used to teleport information between telescopes on the two islands.

The photons did it by quantum entanglement and scientists hope that it will form the basis of a new way of sending encrypted data.

All this confuses me. I understand the spooky action at a distance thing in a basic way when I concentrate on it (and make my head hurt). But I keep reading you can't "break the light-speed limit" even by moving information faster than the speed of light, rather than matter, and yet... they seem to be saying they're transmitting "information."

Can any physicists clue me in? Can you oro can you not exploit this phenomenon to engineer an end-run around the prohibition against sending information at speeds faster than the speed of light?

Thanks to cutaway.

Spooky Action At A Distance For Dummies: This is probably not the best explanation, but it is, I think, close enough.

Particles can become "entangled" such that their quantum states are linked, and must be linked. I think because of some principle like the conservation of spin. Let's say (I'm kinda making this up) a particle with zero spin ejects or degrades into two smaller particles with spin. The smaller particles must have a combined spin equal to zero, as spin, like matter or energy, cannot be created or destroyed. So if one particle spins one way, the other must spin the other, in order to keep the universe's balance-sheet of spins equal. The event that gave birth to them began with zero spin; at the end of the day, they have to have zero spin too, at least when added together. The + spin of one cancels out the - spin of the other and keeps the universe's Chief Financial Officer satisfied.

Futher, the whole Shroedinger's Cat thing applies. At this scale, the actual spin of a particle isa blend of its possible spins (both particles have a fudged spin of kinda positive, kinda negative, kinda inbetween) until it is actually determined which has what spin through testing. Only when actually forced to, by someone peeking, does the universe get around to determining which spin each particle has.

But you can separate these particles by any distance you like. When you determine the spin in one, you simultaneously determine the spin in the other -- even though they could, in principle, be at opposite ends of the universe, so far it could take light itself tens of thousands of years to move from one to the other. The "spooky action at a distance" is a shorthand for this apparent ability of entagled particles to "transmit" information about their own quantum state (and therefore the quantum state the other should, must have) instantanously, blowing the speed of light out the window.

How this is transmitted -- apparently without any sort of carrier wave or other physical vector -- is what makes it "spooky." Nothing moves out to "tell" the other particle what its spin should be; it just happens.

How this could be used for communications I'm not clear on, but I guess it may be possible to one day change the spin in one of the entagled particles, thereby changing the spin in its opposite-spin-twin, and from there you have the basic workings of a binary (+ or - equalling 1 or 0) truly instantaneous communications system.

But then I read that the speed of light also applies to information, so I don't know if this is possible.

An Age of Miracles and Wonders: Trey doesn't sweat the speed of light, figuring that physical law, like some others, is right out the window since 2001:

all i know in the Age of Bush, in which fire can melt friggin' steel, this is totally possible.

posted by Ace at 04:45 PM

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