Quantum Entanglement/Teleportation

[INRM]

Okay, you have two entangled particles. If you destroy one, does the data from the first one become the second one? Or do you have to simltaneously when destroying the first send the data to the second

[Gord_in_Toronto]

Let me look in the Answer Box. Opens lid and looks inside. Ah. The answer is, "NO". Close lid. Waits a minute. Opens lid and looks inside. Ah. The answer is, "YES".

Repeat as necessary. :D

[Ichneumonwasp]

Okay, you have two entangled particles. If you destroy one, does the data from the first one become the second one? Or do you have to simltaneously when destroying the first send the data to the second

Why do you think they are separate particles?

[INRM]

Gord, what's the answer, yes or no?

And Ichnewmonwasp,

Huh? They aren't in the same space, therefore seperate, yet somehow entangled right?

[Paul C. Anagnostopoulos]

There shall be no "destroying" of particles. If one of them undergoes an interaction with other particles, then the original two become disentangled. Or else the entire ensemble becomes entangled. Never been able to get a satisfactory answer.

~~ Paul

[Ziggurat]

Okay, you have two entangled particles. If you destroy one, does the data from the first one become the second one? Or do you have to simltaneously when destroying the first send the data to the second

How do you destroy a particle? You have to make it interact with some other particle(s). That interaction process can create further entanglement of the undestroyed particle with the wave function of the particle(s) which took part in the destruction of the first particle.

[boooeee]

Okay, you have two entangled particles. If you destroy one, does the data from the first one become the second one? Or do you have to simltaneously when destroying the first send the data to the second

What do you mean by "destroy"?

What do you mean by "data"? Are you referring to properties like spin, mass, charge, etc.?

[Ichneumonwasp]

Huh? They aren't in the same space, therefore seperate, yet somehow entangled right?

Well, there's this really interesting idea that someone linked to in an earlier thread about string net liquids (http://www.newscientist.com/article/mg19325954.200) that might possibly mean (if it were correct) that the way we look at space and matter might be a bit off.

It's pure speculation of course, but hey I saw the opportunity to mention it, so I am doing so now.

Really interesting stuff, I think. Particles may not be what we think they are.

[INRM]

Regarding what I was talking about when discussing Quantum Entanglement was related to the phenomenon of Quantum Teleportation...

Also, what's a string-net liquid?

[fuelair]

Hopefully, we understand that for the most part word descriptions really won't do this. The people who play seriously with it use math - very high powered math.

[Ichneumonwasp]

Also, what's a string-net liquid?

Apparently it is a configuration of space-time that we can imagine like a noodle or network with what we call particles representing either the ends or certain points along the space-time net, explaining the entanglement issue -- they actually are entangled (part of the same fundamental structure) not in a weird way, but in a fundamental way. I'm not sure I can makes sense of it physically, but supposedly the math works. I'll have to take their word for that.

[INRM]

Okay... so if one particle in the entangled ensemble alters in any way, it ceases to be entangled?

Am I right?

[Ichneumonwasp]

I have no idea.

ETA

Let me rephrase in a slightly different way -- I'm not sure the question even makes sense in that model.

[Ziggurat]

Okay... so if one particle in the entangled ensemble alters in any way, it ceases to be entangled?

Am I right?

No, you aren't right.

There's a couple of ways of looking at the problem. If you believe in wave function collapse as a discrete process, then particles lose entanglement upon wave function collapse. I don't happen to believe in wave function collapse as a discrete process. Another approach is to consider ensembles (that is, what happens with repeated experiments): the particle may never lose its entanglement, but we may lose information about how that entanglement evolves, so that we cannot see any experimental signature of that entanglement.

Here's how that could play out. Consider two particles entangled such that their spin is opposite. One of the particles interacts with another system which flips its spin. The two particles remain entangled, but now the entanglement is such that they have parallel spins. Well, what if this interaction was random because this other system was in some random, unknown quantum state: then the two particles would be entanged, but we wouldn't know how, and it could be different each time we perform an experiment. One time they might be entangled such that they have opposite spin, one time they might be entangled such that they have parallel spin. Because we no longer have information about how they are entangled, we can no longer determine that they are still entangled, even if they are. In a sense, it doesn't matter if they're still entangled, because once we lose information about how they're entangled, then assuming that they aren't entangled will produce the same results as assuming that they are but in some unknown way.

And how do we lose that information? Easy: make the particle interact with a system with an unknown quantum state, so that we cannot predict how the wave function evolves from that interaction. Which is basically what you need to do to "collapse" the wave function (if you believe in collapse as a discrete process - which I don't). Conversely, though, if we DO know how the wave function evolves from that interaction, we can continue to track the entanglement of the two particles even if one of them is altered. Which is why I said you were wrong.

[INRM]

What does wave function collapse mean?

[Ziggurat]

What does wave function collapse mean?

The answer to that isn't short, and I've got to post quickly, so for the moment I'll just point you here:
http://en.wikipedia.org/wiki/Wave_function_collapse

That should get you a bit of a sense of what's going on. I may post later with some simple scenarios to illustrate the point.

[Soapy Sam]

How can anything be "like a noodle or a network"?

No math please, just language.

[Ichneumonwasp]

If the link can't explain it well enough, then I have no hope since that is my total exposure to it.

The way I interpret it, if this idea is correct, the nature of reality is not what we think it is. The noodle or network is not matter, but spacetime I think. Matter is only a particular manifestation of spacetime, or the energy inherent to spacetime and the entanglement occurs as a result of the nature of spacetime constituted in this way.

I'm not sure any of it makes sense without the math. But it sure is a cool idea to ponder.

[Mojo]

You mean they can teleport homoeopathic remedies (http://ecam.oxfordjournals.org/cgi/content/abstract/4/1/7) as well as send them down phone lines (http://www.guardian.co.uk/obituaries/story/0,,1331927,00.html)?

[mhaze]

the nature of reality is not what we think it is.

Very true. And none of the "magical" phenomena we observe at the subatomic level translate into the world of 3d matter. Well, maybe except for tunneling diodes. Oh wait a minute....there be some commercial products that make money with those quantums? Gimme some quant and biggie fries too. And a quantum computer that would answer all the threads every which way at once...