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billvon

Teleportation achieved over 3 meters

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This is a pretty big deal although it's probably not what you were thinking. For the first time scientists have managed to teleport the state of a nitrogen ion 3 meters across the room. This has big ramifications for both quantum computing and quantum communication.

http://www.sciencemag.org/content/early/2014/05/28/science.1253512

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DanG

Blowing my freaking mind.

Does this imply faster than light communications capability?



Pretty sure not.

If it did, man would I have a few uses for that.

Interestingly, it would be perfectly easy to test it considering three meters is far more than enough distance to check for speed of light violations.
quade -
The World's Most Boring Skydiver

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quade

***Blowing my freaking mind.

Does this imply faster than light communications capability?



Pretty sure not.

If it did, man would I have a few uses for that.

Interestingly, it would be perfectly easy to test it considering three meters is far more than enough distance to check for speed of light violations.

Hmmm...anyone want to invest my my new high frequency trading venture?
"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

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>Does this imply faster than light communications capability?

Probably not. The "probably" is intriguing, but similar, more complex experiments have revealed the two reasons you generally can't win:

1) Entanglement does not produce an observable deterministic change in the entangled particle when the first one is measured. In other words, only after the fact can you go back and say "ok, this result makes sense and the two events happened simultaneously." You can't use the state of the entangled particle to actually receive a signal.

2) Systems that CAN detect a deterministic change are generally limited by lightspeed. (These are not technically entanglement since they rely on additional "confirmation" information sent through some other channel.)

What's intriguing here is that the result in this case does appear both independent and deterministic, which is why the answer is not "definitely not."

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DanG

Does this imply faster than light communications capability?



Now we're just being silly; going faster than the speed of light will require compressing time ahead of you and expanding time behind you.

But on a serious note, if we can teleport to the office, do you think we'll be able to hold a coffee to take with us or still have to go to Starbucks when we get there?
"Pain is the best instructor, but no one wants to attend his classes"

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RMK

Now we're just being silly; going faster than the speed of light will require compressing time ahead of you and expanding time behind you.



Nope.

Consider a blind man in a field five miles away from a thunderstorm. To him, he only knows lightning has struck when he hears the thunder. From his point of view, his sighted friend standing next to him can literally see into the future.

This is precisely what FTL telecommunication would be like.

It wouldn't alter time, it would simply get information to a location faster.
quade -
The World's Most Boring Skydiver

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Quote

Now we're just being silly; going faster than the speed of light will require compressing time ahead of you and expanding time behind you.



If you'll pardon my recall of modern physics 101, I believe the speed of light limit only applies to objects with mass. Quantum states are massless. In fact, they are pretty much "anythingless" so I'm not sure that the speed limit applies.

- Dan G

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>Now we're just being silly; going faster than the speed of light will require
>compressing time ahead of you and expanding time behind you.

Instantaneous communication requires no such thing. (There are a host of other problems though.)

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RMK

But on a serious note, if we can teleport to the office, do you think we'll be able to hold a coffee to take with us or still have to go to Starbucks when we get there?



Screw that. Teleport my Starbucks to me, and skip the office.

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quade

***Now we're just being silly; going faster than the speed of light will require compressing time ahead of you and expanding time behind you.



Nope.

Consider a blind man in a field five miles away from a thunderstorm. To him, he only knows lightning has struck when he hears the thunder. From his point of view, his sighted friend standing next to him can literally see into the future.

This is precisely what FTL telecommunication would be like.

It wouldn't alter time, it would simply get information to a location faster.

Consider a woman in Chicago a few thousand miles away from you. To her, this still doesn't make sense. :(

I read the link from Bill three times before giving up, but it sounds really cool!
There's a thin line between Saturday night and Sunday morning

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Stumpy

Sweet - now they only need to scale it up to people sized objects, and the distance to 12000 miles and I can pop back to the UK for the weekend to visit my parents!



Or have your parents visit you. Why go to the UK ever? :D
cavete terrae.

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cgriff

***But on a serious note, if we can teleport to the office, do you think we'll be able to hold a coffee to take with us or still have to go to Starbucks when we get there?



Screw that. Teleport my Starbucks to me, and skip the office.

It would probably be easier to save a copy locally and reproduce it when you wanted it... assuming you always get the same thing.

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quade

***Blowing my freaking mind.

Does this imply faster than light communications capability?



Pretty sure not.

If it did, man would I have a few uses for that.

Interestingly, it would be perfectly easy to test it considering three meters is far more than enough distance to check for speed of light violations.

As long as they plug everything in the correct way:)

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Calvin19

******Blowing my freaking mind.
Does this imply faster than light communications capability?


Pretty sure not.
If it did, man would I have a few uses for that.
Interestingly, it would be perfectly easy to test it considering three meters is far more than enough distance to check for speed of light violations.
As long as they plug everything in the correct way:)

That's what makes science, science. You publish your experiment and have other attempt to reproduce the results. If they can't, they either disprove you or find the flaw in the experiment. Usually with things like this it's something silly like not taking into account the last few feet of cable or the speed of propagation through the medium, but the next guy's results usually find that flaw pretty quickly.
quade -
The World's Most Boring Skydiver

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Vallerina

Consider a woman in Chicago a few thousand miles away from you. To her, this still doesn't make sense. :(



Then would it blow your mind to know you've never seen anything as it's happening now, but actually seeing things in the recent past? Looking at something just 11 inches away is looking at it one billionth of a second in the past.

I can easily measure that time too. Used to be something I did all the time.
quade -
The World's Most Boring Skydiver

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I read the text of the article and (disclaimer: I'm an electrical engineer involved in the architecture and implementation of very high-speed wireless communication systems and not a quantum physicist) I find this experiement to be interesting from a potential security point of view, but not as a step closer to faster than light communication.

Apparently, experiments to date have methods to a) get the quantum states of two distant particles entangled, b) impart a state on one of the partcles, c) measure the state of that particle, d) transmit some of the information about the measured state to where the second partical is classically, and e) use the classically receieved state information and a local determination to deduce the actual receieved state and confirm that teleportation happened.

What this experiement seems to have focused on is the decoupling of a) from c) and e). Along the way they also demonstrated improved/more reliable methods for performing a), b), and c). What this was not was a decoupling of d) from e).

Unless I'm fundamentally misunderstanding something here, which is entirely possible.

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DanG

Blowing my freaking mind.

Does this imply faster than light communications capability?



Nope. You still need to communicate information about a state from point A to point B in order to perfectly re-create that state at point B, and that communication can occur no faster than the speed of light.

Entanglement can envisioned in a simplistic sense as a bunch of pool balls. If you have a ball that's spinning in one direction and you whang it into a ball that's just sitting there, the first ball imparts a spin on the second ball. At that point, one ball will be spinning in one direction and another ball will be spinning in the opposite direction. That's kind of like what entanglement is.

At a quantum level, you can't just look at the particles and determine which is spinning in which direction. The very act of observing what a particle is doing will change its state. The magic bits, as I understand them, is that the universe doesn't really decide which particle is spinning in which direction until you measure ONE of them. At that point if you see that it's spinning clockwise, you know the other particle is spinning counter-clockwise, wherever in the universe it happens to be at the moment. The other particle is spinning the opposite way because it was always spinning that way after its encounter with the first particle, but the universe didn't actually decide which was which until after you measured it.

The magic parts of this make my brain hurt, but apparently have been proven experimentally. So far at least they don't appear to provide a useful method of communicating information faster than the speed of light or going faster than it either. If some sneaky bastard ever figures out how to exploit some of the underlying effects for that, it'll probably break a good chunk of current physics. That would be fun...
I'm trying to teach myself how to set things on fire with my mind. Hey... is it hot in here?

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