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Researchers quantum teleport particle of light six kilometres

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Re: Researchers quantum teleport particle of light six kilometres

#171

Post by ars »

Ciantic wrote: post #118
TheRealPomax wrote: post #83

Not quite as impressive when you know, and if you don't you should before opening this link, that "quantum teleportation" is not teleportation. It was a cool-sounding name at the time, but has nothing to do with sci-fi style teleportation: nothing disappears from one place and then shows up in another. "Quantum teleportation" is a process of information duplication using particles that already exist, and have been po…

It's easier to think these as random number generators seeded with same value, taken six kilometers apart from each other, and then fetching values from them. No data is transmitted when fetching values from these.

> random number generators seeded with same value

That's basically the https://en.wikipedia.org/wiki/Hidden_variable_theory

Re: Researchers quantum teleport particle of light six kilometres

#172

Post by TheRealPomax »

owaislone wrote: post #148
TheRealPomax wrote: post #83

Not quite as impressive when you know, and if you don't you should before opening this link, that "quantum teleportation" is not teleportation. It was a cool-sounding name at the time, but has nothing to do with sci-fi style teleportation: nothing disappears from one place and then shows up in another. "Quantum teleportation" is a process of information duplication using particles that already exist, and have been po…

Isn't that how actual sci-fi teleportation would work behind the scenes as well? Basically, if I wanted to teleport myself from one city to another. I'd actually die and disappear, and an exact copy myself would be created instantly in the other city. It would be teleportation for the rest of the world but for me it would be death.

If they relied on quantum teleportation: no, not in the slightest. In order to QT a particle (explicitly not using the verb "teleport" here, because it's a very different thing) you need three additional particles for every particle you're QTing. A pair of entangled particles that act as your fascilitator, and a spare particle on the other end to take on the information state of the one you're QTing.

So unless your sci-fi teleporter comes with a massive amount of pre-entangled particles half of which you have, half of which "they" have, plus an equivalent-mass-worth of particles to accept the teleportation subject, it's still just science fiction.

Re: Researchers quantum teleport particle of light six kilometres

#173

Post by echelon »

das3ddddddd wrote: post #136
duaneb wrote: post #99

Earlier quoted context omitted.

At the subatomic level, is there any real difference between information and a "thing"? Seems mostly philosophical and arbitrary at that point.

This is key and why most people don't understand why the name quantum teleportation really is appropriate. And when you consider the only difference between two particles is the information state they are in. And that you do teleport the information. The name is not misleading.

What about position, though?

Re: Researchers quantum teleport particle of light six kilometres

#174

Post by M_Grey »

TheRealPomax wrote: post #83

Not quite as impressive when you know, and if you don't you should before opening this link, that "quantum teleportation" is not teleportation. It was a cool-sounding name at the time, but has nothing to do with sci-fi style teleportation: nothing disappears from one place and then shows up in another. "Quantum teleportation" is a process of information duplication using particles that already exist, and have been po…

You do understand that this has applications that are quite useful though, right? I understand that you're objecting to the terminology, but the actual process is going to be a necessary part of any large-scale "quantum internet", and needs to be mastered.

Re: Researchers quantum teleport particle of light six kilometres

#175

Post by TheRealPomax »

elboru wrote: post #168
aji wrote: post #96

Earlier quoted context omitted.

right, "quantum teleportation" is a woefully misleading name, however this is still an impressive advancement and quantum teleportation will play a key role in wide-area quantum information networks

Since nobody has mentioned it, maybe I didn't understand the implications, but does this mean there is a chance in the future we won't have "bandwidth"? I could replicate data from a server into my personal computer instantly?

Not really. Not unless you and whomever you were getting data from shared entangled particle pairs. While this is a real thing already, some banks use this setup for quantum encryption, it's probabilistic (particles can stop being entangled, so you have to run checks against a series of them and then decide that p>0.999 is good enough for instance) and the owners of each particle is regulated. There is no QT without first making sure two parties each hold half of an entangled pair, and then make sure they both use the same particle for running the QT algorithm against.

Re: Researchers quantum teleport particle of light six kilometres

#176

Post by eternalban »

duaneb wrote: post #169
eternalban wrote: post #161

Earlier quoted context omitted.

I think what you are really asking is: what is the substantial reality of 'the thing', if it is merely 'information' . All following quotes are from the documentary "Atomic Physics and Reality" [1 - 'emphasis' mine.]. John Wheeler: Einstein admired Bohr and Bohr admired Einstein. And you recall that Einstein felt that 'reality' exists, in effect, 'out there', something independent of us. And the position of Bohr was…

Actually, I find it very intuitive that reality is just information. It's much easier than setting it apart as ineffable.

That's not what Bohr said. He said we can't know -- per Bell "have no right to know" -- what is "[objective] reality" [at the atomic scale].

I am personally not comfortable with using 'information'. I think Bohm's formulation "phenomena" is more appropriate. Note that, for example, the manifestation of wave/particle duality is an actual physical phenomena. The 'information' bit is our observation of this phenomena.

And in case the question is still on the table as to are these distinctions merely a matter of philosophical taste or aesthetics?, from same source cited:

Alain Aspect

   At the time of Einstein and Bohr it was just a theoretical
   discussion. You could endorse either Einstein's position or
   Bohr's position, and it was just a matter of taste. 

   And then there was the great discovery by John Bell in '65 that
   it is not only a matter of taste, because according to the 
   position you have at the subatomic point, you have predictions 
   which are not the same. 

   If you follow Einstein you have a certain type of predictions 
   -- that is to say you have results that are in agreement with
   what is called the Bell's inequalities -- and if you follow
   Bohr's position you have another type of prediction which are
   in contradiction, in opposition, with Bell's inequalities.
Aspect at this point had conducted a series of EPR experiments that proved that the Einstein line of reasoning was in contradiction with the obtained experimental results.

Re: Researchers quantum teleport particle of light six kilometres

#177

Post by echelon »

TheRealPomax wrote: post #83

Not quite as impressive when you know, and if you don't you should before opening this link, that "quantum teleportation" is not teleportation. It was a cool-sounding name at the time, but has nothing to do with sci-fi style teleportation: nothing disappears from one place and then shows up in another. "Quantum teleportation" is a process of information duplication using particles that already exist, and have been po…

Dumb, layman question: would it be possible to "quantum teleport" state information from the future?

I've seen articles that describe "sampling" entangled particles statistically without disturbing the entanglement (I assume these are large sets of particles). I've also seen articles that describe properties being affected by future states of the system as the wave function collapses. (Forgive my lack of citation, and poor recollection / understanding.)

Could properties like this be used in conjunction?

Re: Researchers quantum teleport particle of light six kilometres

#178

Post by ethanbond »

aji wrote: post #164
ethanbond wrote: post #120

Earlier quoted context omitted.

I'm only a layman who's mildly interested in this, but this contradicts my understanding... Someone correct me if I'm wrong here. You can't communicate with quantum teleportation. It sends random "information" (not information at all), because you can't control how the quantum waveform collapses. So you have to collapse the waveform, create a key that encodes your collapsed form to the information you want to transmi…

you can't "communicate", but it would be useful for qubits in one quantum computer to be sent to another quantum computer without physically moving the qubit. that was what I meant by wide-area quantum information networks

Oh totally agreed. My response wasn't to your comment, but to a comment implying that aliens are communicating "across" us but never through us via means of quantum teleportation and that's why can't detect them.

I agree with you, this is impressive and probably will be very helpful some day.

Re: Researchers quantum teleport particle of light six kilometres

#179

Post by adamsea »

TheRealPomax wrote: post #170
johncolanduoni wrote: post #135

Earlier quoted context omitted.

You've compounded their lazy science reporting by making quite a few mistakes yourself in your description: 1. There is no duplication or copying of information, the original particle's state is destroyed. Copying is impossible when dealing with general quantum states[1]. (You may be thinking of measuring an entangled pair to randomly produce a stream of classical bits on each side that is the precise inverse of what…

"Duplication" was the wrong term, I should have said "destructive-read/write", which I did in another comment. 2. There is no teleportation in the common man, sci-fi interpretation. In order to effect the information transferral we need three times as many particles as we're transferring the information of. Per particle whose state is to be tranferred, we need two entangled particles and a target particle. To transla…

What common sci-fi man?

Re: Researchers quantum teleport particle of light six kilometres

#180

Post by smsm42 »

stephengillie wrote: post #103
TheRealPomax wrote: post #83

Not quite as impressive when you know, and if you don't you should before opening this link, that "quantum teleportation" is not teleportation. It was a cool-sounding name at the time, but has nothing to do with sci-fi style teleportation: nothing disappears from one place and then shows up in another. "Quantum teleportation" is a process of information duplication using particles that already exist, and have been po…

This is, very confusingly, "teleportation of the quantum state". Not unlike how merging a pull request is "teleporting the software state of your repo", but instantaneously. Essentially this is just entanglement at 6 kilometers, described by a blustery article.

Not sure about "instantaneously" part. It's more like I send you a pull request and then I apply it to my repo and tell you to apply it to your repo and you get your repo in certain state which I knew upfront. Repo state teleportation!

Yeah, it know it's not exactly that either, but it's about as magical as that, AFAIU. Which doesn't say it's not useful - ability to merge pulls and get all the repos in certain state is hugely useful - but calling it "teleportation" implying that we're on the verge of being beamed up and down like StarTrek characters sounds a bit more pompous than warranted.

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