Quantum teleportation achieved over ten miles of free space Options

[TheWanderingJewe...]

http://arstechnica.com/science/news/2010/0...=1#comments-bar

Quantum decking anyone?

[Propaganda]

http://arstechnica.com/science/news/2010/0...=1#comments-bar

Quantum decking anyone?

Um...not really. The whole idea with quantum entanglement is that you end up with two identical photons (for example), and if you make a change to photon A (which, for the purpose of this example, is in Europe) the same change will be made to photon B (which, for this example, is in America).

So it would only work if you had data transferred in a medium that COULD be entangled, and then you would have to have an identical medium for every single node you wanted to work on. This would also raise some really awkward questions when a corp starts asking why you've got an exact match for a quantum entangled storage device they happen to own.

What that technology WOULD be useful for, however, is instantaneous communication between two disparate points. But it'd be prohibitively expensive at the same time, not to mention extremely limited.

[Draco18s]

And you can still only send quantum information, you can't send normal information (e.g. internet data, strings, 1s and 0s, voice, picture...) at least, not yet.

[Banaticus]

So, what's this quantum entanglement entail? It's not 1's and 0's that spell out "cat", it's actual live and dead cats? (IMG:style_emoticons/default/wink.gif) Why can't this "quantum information" be used to send real information?

[Hand-E-Food]

Converting usable data in quantum is just the next step. (IMG:style_emoticons/default/wink.gif)

I read yesterday about a chip that stores data on a quantum level. Tiny dot speeds hi-tech future.

[Draco18s]

So, what's this quantum entanglement entail? It's not 1's and 0's that spell out "cat", it's actual live and dead cats? (IMG:style_emoticons/default/wink.gif) Why can't this "quantum information" be used to send real information?

You entangle* two particles such that they both have the same quantum state. That is, their spin.

Then as you change one, the other changes in the same manner.

It's really hard to explain, even by physicists. Mainly because what causes it can't be observed (attempting to do so causes the experiment to fail).

Good movie to watch, "What the Bleep Do We Know!?: Down the Rabbit Hole"

*The way this is done is by creating a projection of particles (protons -> light) and separating out each particle based on its spin. The "Clockwise" particles are attracted in one direction, the "Counterclockwise" in another. Each of the two fields will have a the same spin as every other particle in that field and the opposite spin from the particles in the other field. By clever manipulation of where these fields overlap, you can create areas where any given particle has a spin different from every other particle.

Its one of those weird "measure it and it changes" things.

[Zormal]

Very good explanation, Draco18s.

I'd be a bit wary of What the Bleep Do We Know, though. While a very entertaining and eye-opening movie, it contains many factual errors and misinterpretations that might be a bit difficult to spot, especially if you're not all that much into physics.

[Dixie Flatline]

It's really hard to explain, even by physicists. Mainly because what causes it can't be observed (attempting to do so causes the experiment to fail).

My favorite QM quote ever came from I believe an MIT professor:

"If Quantum Mechanics makes sense to you, you obviously haven't studied it enough yet."

The biggest thing I could see with entanglement would be instantaneous, 100% secure communication channels. It would be literally hack-proof, since the act of hacking would destroy the entanglement or contaminate the connection enough to betray tampering.

[Draco18s]

I'd be a bit wary of What the Bleep Do We Know, though. While a very entertaining and eye-opening movie, it contains many factual errors and misinterpretations that might be a bit difficult to spot, especially if you're not all that much into physics.

True, but it at least attempts to explain quantum mechanics to the layman. It might not be factually perfect, but it isn't boring to watch.

[Werewindlefr]

I'd be a bit wary of What the Bleep Do We Know, though. While a very entertaining and eye-opening movie, it contains many factual errors and misinterpretations that might be a bit difficult to spot, especially if you're not all that much into physics.

As a grad' student in particle physics, I tend to avoid these movies as much as I can. They tend to make me cry.

I have yet to see any documentary film about quantum mechanics that doesn't end up saying a pile of crap at some point. Quantum Cafe, one of the parts of the "Elegant Universe", has been praised as an "excellent introduction to QM", is full of major errors (that bias for the manyworld interpretation of QM is just wrong and talking about it as if it was scientific fact is totally misguiding) and inaccuracies.

As for the so-called quantum teleportation, it is an interesting phenomenon but a misnamed one; nothing is teleported, and as opposed to what lots of pseudo-scientific works of fiction (or even worse: popularization mags) often say -I'm looking at you, Eclipse Phase-, it doesn't allow to cheat special relativity. No FTL comms through this stuff. Of course, that makes the truth far less sexy than the fiction or mags.

[Draco18s]

As for the so-called quantum teleportation, it is an interesting phenomenon but a misnamed one; nothing is teleported, and as opposed to what lots of pseudo-scientific works of fiction (or even worse: popularization mags) often say -I'm looking at you, Eclipse Phase-, it doesn't allow to cheat special relativity. No FTL comms through this stuff. Of course, that makes the truth far less sexy than the fiction or mags.

Agree with all points.
(I should point out that I'm a digital arts major, but I really enjoyed reading about theoretical physics.
Had to watch What the Bleep Do we Know!? in a Metaphysics course and I pointed out the flaws in some of the stuff that was said.)

[The Mighty Sherp...]

I still do not understand why information is not able to be transmitted through this medium. Instead of 0 and 1 you have a spin direction. But is that not the same net effect as on and off just with more possibilities? And why would those other possible spin directions stop you from translating one spin direction to 0 and another to 1 to transmit your data? I am quite confused by the people saying this.

[Draco18s]

I still do not understand why information is not able to be transmitted through this medium. Instead of 0 and 1 you have a spin direction. But is that not the same net effect as on and off just with more possibilities? And why would those other possible spin directions stop you from translating one spin direction to 0 and another to 1 to transmit your data? I am quite confused by the people saying this.

Honestly I haven't figured out why not either.

[KarmaInferno]

I still do not understand why information is not able to be transmitted through this medium. Instead of 0 and 1 you have a spin direction. But is that not the same net effect as on and off just with more possibilities? And why would those other possible spin directions stop you from translating one spin direction to 0 and another to 1 to transmit your data? I am quite confused by the people saying this.

It has something to do with the very act of reading the particle's state, alters the particle's state.

I dunno. QM gives me a headache.



-karma

[Cray74]

Practical Shadowrunning implications:

1) The information has to be transferred between particles conventionally.

Generally, the entanglement information is sent by fiber optic cables. In this case, it was sent by (if I'm reading this link correctly) light (laser?) transmission between two telescopes. ("The research team designed two types of telescopes to serve as optical transmitting and receiving antennas.")
http://www.physorg.com/news193551675.html

The reason I bring this is that a lot of science fiction stories are all too happy to suggest that "quantum entangled particles" can be "entangled" without any tangible connection, even allowing communications to exceed the speed of light. This isn't correct - conventional, speed of light limits apply, and you need some sort of mundane transmitter and receiver (radio, fiber optic, etc.)

2) It's also important to note that the entangled particles stay separate. Star Trekkian teleportation ain't happening because matter isn't moving. You're exchanging information, not mass.

[crash2029]

I think I need to go have a talk with the Illusive Man.

[TheWanderingJewe...]

an article on the subject......I'm a bit vague on it

http://en.wikipedia.org/wiki/Quantum_entanglement

[Daylen]

The reason I bring this is that a lot of science fiction stories are all too happy to suggest that "quantum entangled particles" can be "entangled" without any tangible connection, even allowing communications to exceed the speed of light. This isn't correct - conventional, speed of light limits apply, and you need some sort of mundane transmitter and receiver (radio, fiber optic, etc.)

aye. gets tiring after a dozen times hearing someone has a new way to do something faster than the speed of light.

[The Tarasque]

Im more confused now!

So youre saying that it cant be observed and its no faster than any other form of communication. So um what good is it?

I thought the whole point of entanglement was the effect when observed anyway. That normally when you observe the state it has a random chance of being any spin, but if they are entangled then when you observe them they have the same spin direction. Is this not accurate? And if it is why is it useless for transmitting information? And if its useless for transmitting information what in blue blazes is the point of it and how is anyone able to tell that they are in fact entangled at all?

The answers in this thread make very little sense to me!

[Draco18s]

I thought the whole point of entanglement was the effect when observed anyway. That normally when you observe the state it has a random chance of being any spin, but if they are entangled then when you observe them they have the same spin direction. Is this not accurate? And if it is why is it useless for transmitting information? And if its useless for transmitting information what in blue blazes is the point of it and how is anyone able to tell that they are in fact entangled at all?

I believe they actually have the opposite spin.

And its not so much that it's useless to transmit information, its that it doesn't transmit it any faster.

Case and point, you can make light itself travel faster than light. But as I understand it, in so doing, you lose any information encoded into the beam.

[Shinobi Killfist]

I think I need to go have a talk with the Illusive Man.

It is sci-fi so it works. Seriously no one knows what the future holds. All too many times in history we have found out new ways to abuse physics so things we thought we knew we no longer know the same way. Why is there this weird assumption that this time we got it right? So maybe some time in the future they can find a way to make quantum entanglement break the FTL barrier and be a form of instantaneous communications. As sci-fi goes mass effect was nice in that is maintained a pretty nice balance between soft and hard sci-fi.

[KarmaInferno]

I think I need to go have a talk with the Illusive Man.

I have to find the article again, but it discussed the "real science" behind many video games.

When they asked a physicist about the Mass Effect quantum-entangled comms, it basic response it that the comms are bullshit. Wouldn't work.




-karma

[Daylen]

Im more confused now!

So youre saying that it cant be observed and its no faster than any other form of communication. So um what good is it?

I thought the whole point of entanglement was the effect when observed anyway. That normally when you observe the state it has a random chance of being any spin, but if they are entangled then when you observe them they have the same spin direction. Is this not accurate? And if it is why is it useless for transmitting information? And if its useless for transmitting information what in blue blazes is the point of it and how is anyone able to tell that they are in fact entangled at all?

The answers in this thread make very little sense to me!

In fact as an information transfer system it is useless! why? because you have to know when to observe the particle. look too soon and you will change its state by looking at it. Also once the entangled particles have been observed and have their own spins they are not going to be entangled anymore so their spins are not coupled.

[Daylen]

It is sci-fi so it works. Seriously no one knows what the future holds. All too many times in history we have found out new ways to abuse physics so things we thought we knew we no longer know the same way. Why is there this weird assumption that this time we got it right? So maybe some time in the future they can find a way to make quantum entanglement break the FTL barrier and be a form of instantaneous communications. As sci-fi goes mass effect was nice in that is maintained a pretty nice balance between soft and hard sci-fi.

because information is bound by the speed limit of light. One might as well consider sending string theory to send photons faster than the speed of light. breaking the FTL barrier is not like breaking the sound barrier, but harder. being able to send a photon into a vacuum and then catch up with it in an Einstein gedanken experiment manner is theoretically impossible. The theory that says so is a modification on Newtons Laws and has been proven many times.

[IceKatze]

hi hi

I found This Review to be informative about the veracity of the aforementioned quantum physics movie.