Faster than light communication???

[fuhrerkeebs]

He's trying to make an anology between the discrete of the micro-universe (such as the energy levels of the hydrogen atom) and the speed of light in the macro-universe. His analogy is wrong, however, because he doesn't take into account the superposition of particles.

[Thales]

You can't have information travelling faster than the speed of light. It would provide a means to violate causality by being able to 'see' things before they occur in your frame of reference.

 

See SR: Invariance or Minkowski Diagrams

[Sayonara]

what the hell did you just say? I have read the majority of your posts, and none of them make sense.

Stop trolling other members, now.

 

You can consider this an official warning.

[Severian]

Skoteinos is correct. Entanglement cannot be used to send information fater than the speed of light. You are not sending information - you are just inferring knowledge of the other particle by using physical laws.

 

As for teleportation, you are sending a particle, but it becomes a little subjective as to whether it is the same particle (how do you define this anyway?). The point is that once you measure a property of the particle which does not commute with position, the wavefunction is put in a state which does not have a defined position - by measuring position later, it has a non-zero chance of being a long way away. But it performing these measurements you change the nature of the particle, so is it the same particle?

 

But all this is statistical - the chance of success is very small even for one particle, so for many particles it is really tiny. So you may be able to teleport a human like this in principle, but the probability of success would be 0.00000000000000000000000000000000000000000000000001% (or somesuch) and decrease with distance. Would you be willing to risk this?

[swansont]

As for teleportation' date=' you are sending a particle, but it becomes a little subjective as to whether it is the same particle (how do you define this anyway?). The point is that once you measure a property of the particle which does not commute with position, the wavefunction is put in a state which does not have a defined position - by measuring position later, it has a non-zero chance of being a long way away. But it performing these measurements you change the nature of the particle, so is it the same particle?

 

But all this is statistical - the chance of success is very small even for one particle, so for many particles it is really tiny. So you may be able to teleport a human like this in principle, but the probability of success would be 0.00000000000000000000000000000000000000000000000001% (or somesuch) and decrease with distance. Would you be willing to risk this?[/quote']

 

<sigh>

 

With teleportation you are not sending a particle. You are sending information about the particle, e.g. the orientation of a spin-polarized atom.

 

Despite the use of the word, it has nothing to do with Star Trek.

[Severian]

<sigh>

 

With teleportation you are not sending a particle. You are sending information about the particle' date=' e.g. the orientation of a spin-polarized atom.

 

Despite the use of the word, it has nothing to do with Star Trek.[/quote']

 

Rubbish. You are not sending information. Please explain how one can send information in this way - you can't! Even although QM is non-local, it does not violate causality. The information is already there, inherent in the system.

 

You are confusing the EPR 'paradox' with 'teleportation'.

 

The entire point of 'teleportation' is to put the particle into a (position-space) wavefunction which is spread out, and then collapse it onto an eigenstate which is dirac-delta function at some other point a long way away. The entanglement is used to collapse the wavefunction 'remotely'. But as I pointed out, there are two problems with this. Firstly, you aren't really teleporting anything since the potentiality of the particle being at the position is already there (you are just delaying your realisation that it is). Secondly even if this can be done for one particle it cannot be done (realistically) with an ensemble.

 

Who mentioned Star Trek anyway?

[unknow force]

Hello, well i think that the quantical concepts at least left that possibility to travel more fast than the light, im interested about that laser experiment, anyone have some information about it??????????

 

You can't have information travelling faster than the speed of light. It would provide a means to violate causality by being able to 'see' things before they occur in your frame of reference

 

Yes,yes,yes,yes,yes,yes,yes,yes,yes, thats was one of the effects in that experiment, supossely is like an time machine.

[swansont]

Rubbish. You are not sending information. Please explain how one can send information in this way - you can't! Even although QM is non-local' date=' it does [b']not[/b] violate causality. The information is already there, inherent in the system.

 

You are confusing the EPR 'paradox' with 'teleportation'.

 

The entire point of 'teleportation' is to put the particle into a (position-space) wavefunction which is spread out, and then collapse it onto an eigenstate which is dirac-delta function at some other point a long way away. The entanglement is used to collapse the wavefunction 'remotely'. But as I pointed out, there are two problems with this. Firstly, you aren't really teleporting anything since the potentiality of the particle being at the position is already there (you are just delaying your realisation that it is). Secondly even if this can be done for one particle it cannot be done (realistically) with an ensemble.

 

Who mentioned Star Trek anyway?

 

I never said anything about violating causality.

 

Here is a brief explanation of quantum teleportation. There is nothing about it that suggests that you are moving a particle around; the first sentence (emphasis added) is "In quantum teleportation, an unknown quantum state is faithfully transferred from a sender (Alice) to a receiver (Bob)"

[ydoaPs]

they don't "teleport" things in star trek. they "transport" things

[RICHARDBATTY]

Once the states of the entangled pair are known then what. If you have tr ansported a limited amount to a remote location how can you use this again.trolling, flaming, spamming whats this. If you have just joined the thread ingnore this and read the first post.

[Rasori]

Assuming that eventually we could get skilled enough to teleport a large mass of atoms (say, a mass of atoms that could make a CD...) wouldn't that be enough to teleport the information?

It wouldn't be instant, but by the time we get that far in teleportation we'd likely be able to write the communication to a CD much quicker than now. Once you've written it to the original CD, can you not teleport this CD to another location to be read there? When you're talking about interstellar distances, this would shave years off the time, in theory.

 

I'm basing this on what Skoteinos said earlier:

The Quantum Entanglement of today is quite useless for information transfer, but quite useful for particle transfer, aka teleportation, though we're only at the stage of 1 to a few particles (photons/atoms?)

 

Oh, by the way, I am new to this stuff, so go ahead and correct me if this was a completely idiotic question.

 

EDIT: Another advantage to this is that even if the likelihood of success is quite slim, it isn't hard to create another CD and try again.

[TheProphet]

Well even IF we could teleport an single atom, electron, well "particle" It's still within the Quant world and subject to it's specifik laws! Altough I belive indeed photons can do a little more magic ! But on the macro scale! Such as us Atoms don't behave the same anymore, as most of you already know! So teleporting larger systems would need all atoms in the same state ! Such as like a Superconductor is behaving. This would indeed get into trouble with us humans! I belive this is a little of what "Uknown force" was trying to say also...

[swansont]

Oh, fer crying out loud...

 

 

THE ATOMS DON"T GO ANYWHERE!

[swansont]

they don't "teleport" things in star trek. they "transport" things

 

That's an important point, because the words have such dissimilar meaning...

[Rasori]

Swanson, if that post about the atoms not moving was directed at me, I know that. But copies of the atoms do, or at least in theory would. Much like a fax, the original CD would disappear and a copy of it would appear elsewhere.

[swansont]

Swanson, if that post about the atoms not moving was directed at me, I know that. But copies of the atoms do, or at least in theory would. Much like a fax, the original CD would disappear and a copy of it would appear elsewhere.

 

No, the closest analogy would be burning a CD that was very far away, but the blank CD was already there, and the original CD is erased in the process. You are moving information about a state of an atom, nothing else. No matter is teleported. All of the atoms provided in the experiment exist beforehand and afterward, in the same locations.

[Severian]

Oh' date=' fer crying out loud...

 

THE ATOMS DON"T GO ANYWHERE![/quote']

 

That is completely subjective. Particles with the same properties are indistinguishable, so it is just a matter of semantics as to whether or not it is the 'same' quantum state or not. the initial state is destroyed by Alice's measurement and the second is made by Bob by phase-space displacement.

 

Since you like Star Trek so much, think of it this way: when Kirk is 'transported' he is supposedly broken down into atoms and reconstructed at the other end. It doen't make any difference whether they are the same atoms or not at the other end. It is only their assembly which is important, so Kirk could be teleported by just sending the imformation (as long as he could be reconstructed at the other end).

[5614]

that is not what quantum teleportation does, all quantum teleportation does it "teleport" the properties, thats spin for an atom, polerisation for a photon... no matter is moved, "teleportation" as you say is not yet humanly possible.

 

the reason quantum teleportation IS useful is for quantum computers where these properties can represent data, there are many threads on this, use the search.

[Guest KnowingIsKey]

Wouldn't it be possible to polarize the spin alignment of an entangled particle located at one end, then check the polarization on the other end at a different time? Then if so, someone could continue changeing the spin on location 1 at a set time interval (not observing, but changing the spin alignment with polarization), and location 2 would observe the spin, moments after the assumed polarization was done at location 1. Continuing this process should result in binary data unidirectional. For a return response you could use the same proccess in reverse using another entangled pair.

 

Example:

 

Time Action

-------------------

16:04:01 Loaction 1 polarize spin axis x up

16:04:02 Location 2 observe spin axis x

16:04:03 Loaction 1 polarize spin axis x down

16:04:04 Location 2 observe spin axis x

16:04:05 Loaction 1 polarize spin axis x up

16:04:06 Location 2 observe spin axis x

[Aeschylus]

Wouldn't it be possible to polarize the spin alignment of an entangled particle located at one end' date=' then check the polarization on the other end at a different time? Then if so, someone could continue changeing the spin on location 1 at a set time interval (not observing, but changing the spin alignment with polarization), and location 2 would observe the spin, moments after the assumed polarization was done at location 1. Continuing this process should result in binary data unidirectional. For a return response you could use the same proccess in reverse using another entangled pair.

 

Example:

 

Time Action

-------------------

16:04:01 Loaction 1 polarize spin axis x up

16:04:02 Location 2 observe spin axis x

16:04:03 Loaction 1 polarize spin axis x down

16:04:04 Location 2 observe spin axis x

16:04:05 Loaction 1 polarize spin axis x up

16:04:06 Location 2 observe spin axis x[/quote']

 

No it's not possible, though you alter the combined wavefunction of the two particles, polarizing one of them does not affect the expectation value of the other.

[swansont]

Wouldn't it be possible to polarize the spin alignment of an entangled particle located at one end' date=' then check the polarization on the other end at a different time? Then if so, someone could continue changeing the spin on location 1 at a set time interval (not observing, but changing the spin alignment with polarization), and location 2 would observe the spin, moments after the assumed polarization was done at location 1. Continuing this process should result in binary data unidirectional. For a return response you could use the same proccess in reverse using another entangled pair.

[/quote']

 

Changing the spin of 1 destroys the entanglement. Measuring the spin of 2 destroys the entanglement.

[MadScientist]

Changing the spin of 1 destroys the entanglement. Measuring the spin of 2 destroys the entanglement.

 

I'm trying my best to follow all this but I'm struggling.

 

I'm not sure what Swan means here, does s/he mean once you've spun the sender and measured the receiver that the linked pair is broken so you can only send one "bit" of data then that's it, you need to create a new pair...

Or is there a way to preserve the pair??

 

 

And as amazing as these entangled pairs are isn't it going to be more amazing to find out how the reflection can be sent over vast distances?? Be it passing through another dimension or using some unknown as yet energy force like tachyons or something like that.

Like if we find out an interdimensional thingy was created we could do it on a larger scale.

 

And aren't a lot of people forgetting this is all early days for entangled particles?? Saying you simply CANNOT do this or that and you can only do this and this with them, isn't that like saying radio waves are ONLY good for sending out radio signals, when we frist discovered them. Yet now we have radar, television and other things.

Do we know for a fact that they have these limitations and we'll never discover new things about them??

 

And how the Hell do you create an entangled pair of particles in the first place??

I've seen a few sites on the subject and they all go babbling on about sending this and that from one particle to another but not how to create them. Is it really simple or do you need a 20 mile long particle accelerator because these quantum computers are gonna be a bit cumbersome if they do, I'd have to move into a bigger house.

 

Does anyone know of a site that explains this kind of thing in simpler terms??

 

The other thing that puzzles me is this photon teleportation or whatever.

If you can send a photon from one location to another is there any reason we can't send other types of particles??

Because I was wondering about electrons. Instead of a cable to carry electricity, create a lot of entangled pairs and send the current through those.

 

What about an entangled pair television/monitor screen?? An array of entangled pairs acting as receivers on the monitor screen and an array of transmitters on the graphics card sending the photons that way. A monitor/TV like that would put these LCD tubeless systems to shame.

I suppose it would take quite a lot of particles though...

[swansont]

I'm trying my best to follow all this but I'm struggling.

 

I'm not sure what Swan means here' date=' does s/he mean once you've spun the sender and measured the receiver that the linked pair is broken so you can only send one "bit" of data then that's it, you need to create a new pair...

Or is there a way to preserve the pair??

[/quote']

 

There is no way to preserve the pair. Once you make a measurement, i.e. do anything that interacts with the particle, the entanglement is destroyed.

[Guest professorCM]

CDs work with binary code why not just use an excellerator to fire a stream of microscopic particles in binary code such as proton standing for 1 and electron as 0 because even if cds are way more advanced there still are limited. If you had a more powerful excellerator that could be more efficient.

[5614]

nearly everything works with binary when you are talking about computers... CDs included.

the thing with the profs idea is that it (a) needs a connecting wire (b) works at the speed of light for the photon and the speed of electricty for electron.

fibre optic wires [already in use] for at the speed of light, electrons are already used in normal wires.... so we're none the better off with your idea. [soz, didnt mean to be rude]

 

the thing with entaglement is that [in a sense, to allow people to understand] is that you are binding the two atoms to the same future, of spinning in a certain way etc, however, obviously if you change the spin of one, they will no longer have the same future therefore there's nothing in common so there is no 'entagle bond'.

whilsts this is NOT how it works, it should allow people to get the general idea of that you cannot alter one, or you can, but it wont effect the other.