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Scientists Find Method To Reliably Teleport Data

Soulskill posted about 6 months ago | from the who-needs-gigabit-fiber-anyway dept.

Science 202

An anonymous reader writes "Scientists at the Kavli Institute of Nanoscience say they've managed to reliably teleport quantum information stored in one bit of diamond to another sitting three meters away (abstract, pre-print) . Now, their goal is to extend the range over a distance of a kilometer. '[R]eliability of quantum teleportation has been elusive. For example, in 2009, University of Maryland physicists demonstrated the transfer of quantum information, but only one of every 100 million attempts succeeded, meaning that transferring a single bit of quantum information required roughly 10 minutes. In contrast, the scientists at Delft have achieved the ability "deterministically," meaning they can now teleport the quantum state of two entangled electrons accurately 100 percent of the time. They did so by producing qubits using electrons trapped in diamonds at extremely low temperatures. According to Dr. Hanson, the diamonds effectively create 'miniprisons' in which the electrons were held. The researchers were able to establish a spin, or value, for electrons, and then read the value reliably.'"

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This research should receive enormous funding. (3, Insightful)

Anonymous Coward | about 6 months ago | (#47127859)

Can you imagine the boner the high speed traders would have if someone figured out a way to communicate information from New York to Chicago or London instantaneously?

Re:This research should receive enormous funding. (5, Informative)

TeknoHog (164938) | about 6 months ago | (#47127907)

You can't use quantum teleportation to transmit information faster than light. QT requires a classical information channel (like fiber optic cables) on the side to actually work. The point about QT is being able to transfer a quantum mechanical state, i.e. the wavefunction with its full phase information. You cannot do that with classical means, because you'd need to measure the state, thereby collapsing it into a classical state.

Re:This research should receive enormous funding. (3, Funny)

fuzzyfuzzyfungus (1223518) | about 6 months ago | (#47127943)

At least poor Erwin can finally bring his cat with him when he travels.

Re:This research should receive enormous funding. (5, Informative)

barlevg (2111272) | about 6 months ago | (#47127969)

I realize you were making a joke based on a perception common in popular culture, but the truth is that the Schrodinger's Cat paradox has a simple resolution: the cat *cannot* be both alive and dead because the detector (which detects whether the decay has occurred and which triggers the release of the poison if the decay occurred) collapses the wave function of the particle. There's no such thing as a passive detector. So while a subatomic particle could indeed exist in a superposition of "decayed" vs. "not decayed," the second you go about asking the particle whether it's decayed (that is, when you set up the detector), the wave function collapses, and no superposition is possible.

Re:This research should receive enormous funding. (2)

fuzzyfuzzyfungus (1223518) | about 6 months ago | (#47128001)

I think that that was more polite and informative than my fairly feeble joke deserved. My thanks.

Re:This research should receive enormous funding. (1)

Anonymous Coward | about 6 months ago | (#47128095)

Except that it's bullshit. For example photons in air constantly get absorbed and reemitted by air molecules without their wavefunction collapsing.

When the most prestigious place where his pet solution is published is Slashdot, you know something is wrong.

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128357)

Except that it's bullshit. For example photons in air constantly get absorbed and reemitted by air molecules without their wavefunction collapsing.

When the most prestigious place where his pet solution is published is Slashdot, you know something is wrong.

No. Just no.

Re:This research should receive enormous funding. (2)

barlevg (2111272) | about 6 months ago | (#47128417)

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128473)

That is not a correct interpretation of objective collapse theory though, and is either overly simplified or a misinterpretation, assuming it is even an explicit example in the cited source. There are practical problems of setting up Schrodinger's cat in a real world experiment and having it properly isolated from outside environment, plus issues with cleanly defining a dead and alive state, but in principle it is no different than much simpler experiments which can be setup, and with which careful measurements can be done. Objective collapse is an interpretation of quantum mechanics, and can't disagree with the mathematical predictions and observations, which all allow for superpositions to be setup in even complex setups.

Re:This research should receive enormous funding. (1)

barlevg (2111272) | about 6 months ago | (#47128633)

Yep. Sorry about that. I meant to link to the Niels Bohr answer above it (which I copy-pasted into a separate response below).

Re:This research should receive enormous funding. (1)

Anonymous Coward | about 6 months ago | (#47128435)

Except both you and barlevg are incorrect in this case. Barlevg incorrectly assumes that a detector within a closed system collapses the state when this runs counter to the very concepts used to create entangled states. Also the idea that a photon constantly gets absorbed and reemitted in air is an incorrect understand of how electromagnetic waves get delayed, both in the classical electromagnetic sense and quantum sense. There is a minute interaction between a photon propagating through air and the components of the air since the photon has electric and magnetic fields that induce slight currents and polarizations in air molecules. But the result most of the time is no change, no passing of information and no indication that the photon was there after it passes. This amounts to something analogous in quantum mechanics referred to a weak measurements, where the less information you get from an interaction, the less it affects the state being interacted with. In a weak enough case, you can pass most photons through unperturbed, although there will be occasional ones that do have a strong interaction, that do actually get absorbed and scatter off of molecules. But in general, that is not the process of light going through air (at least until you get to high energy x-rays and gamma rays, where the index of refraction gets less and less relevant, and they propagate through air like billiard balls on a scale you can measure in a undergrad lab class).

Re:This research should receive enormous funding. (1)

barlevg (2111272) | about 6 months ago | (#47128535)

Also the idea that a photon constantly gets absorbed and reemitted in air is an incorrect understand of how electromagnetic waves get delayed, both in the classical electromagnetic sense and quantum sense.

Totally willing to admit that I'm wrong about this, but could you provide a citation? This interpretation of why light is slower in a medium was something I picked up in undergrad, and I never had it explicitly contradicted (my Ph.D was in a sub-field that required only the bare minimum quantum mechanics and solid state courses).

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128611)

Just consider the electromagnetic radiation solution to the Maxwell equations in a medium. It might seem more intuitive when considering this for radio waves that are way larger than electronic structure and have easier to picture current and polarization effects on the medium. The idea of photons doesn't really change this result except at the smallest scales, especially considering visible light photons still have wavelengths much larger than atoms. Also consider what process an atom can absorb and re-emit light, which would have no guaranteee of sending the light off in the same direction and energy for arbitrary energy photons. Look in to Compton scattering to see what happens when an atom does interact with light that way, and the result is a recoil in the atom and a change in the photon's momentum and energy.

Re:This research should receive enormous funding. (1)

barlevg (2111272) | about 6 months ago | (#47128783)

Right. Okay. So where I went wrong here was the "absorb" and "re-emitted" part, but the interpretation that stuck with me from undergrad was the question of, when interactions of this type occur, does it make sense to think of the photon as the same photon pre- and post- interaction? Or can we think about this as the photon destroyed and replaced with a new one that is travelling in roughly the same direction? If I recall correctly (it's been four years, so pardon me if I'm wrong), since [a,a^+]=0 for bosons, then the answer is, "sure, if you want," because you can create+annihilate a boson as many times as you want with no difference. So it's just an interpretation. But yeah, it doesn't sound like it's a good answer to why light travels slower in a medium.

Ignore previous reply (2)

barlevg (2111272) | about 6 months ago | (#47128447)

Sorry. Linked to the wrong section. This is the relevant answer [wikipedia.org] , and it's as old as the paradox itself:

However, one of the main scientists associated with the Copenhagen interpretation, Niels Bohr, never had in mind the observer-induced collapse of the wave function, so that Schrödinger's cat did not pose any riddle to him. The cat would be either dead or alive long before the box is opened by a conscious observer.[6] Analysis of an actual experiment found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before there is any conscious observation of the measurement.[7] The view that the "observation" is taken when a particle from the nucleus hits the detector can be developed into objective collapse theories. The thought experiment requires an "unconscious observation" by the detector in order for magnification to occur. In contrast, the many worlds approach denies that collapse ever occurs.

Re:Ignore previous reply (2, Informative)

Anonymous Coward | about 6 months ago | (#47128499)

But a Gieger counter sitting on some table is well coupled to the lab and environment around it and would allow for coherence as with any other interaction outside the closed system under consideration. If you could construct a way of isolating a cat from the environment, you could use the same method on a gieger counter, and then the effects of "unconscious observation" would go away in a closed system. Things like this have been tested on a smaller scale using detection methods that can be isolated or not, and in the isolated cases superposition returns.

Re:Ignore previous reply (1)

Anonymous Coward | about 6 months ago | (#47128629)

But a Gieger counter sitting on some table is well coupled to the lab and environment around it and would allow for decoherence as with any other interaction outside the closed system under consideration.

Missed a rather important "negative sign."

Re:This research should receive enormous funding. (3, Informative)

NotDrWho (3543773) | about 6 months ago | (#47128019)

Anyone remember the movie "Mystery Men"? One of the characters in that movie summed up my feelings on modern quantum physics pretty nicely. He was "Invisible Boy." But he could only become invisible when no one was looking (not even himself), and no cameras were on him. The second that anything that could actually verify his ability tried to do so, he became visible again. This led to the obvious question "How do you know you have this power at all?" to which he relied "Well, I just feel it."

Re:This research should receive enormous funding. (2)

Gr8Apes (679165) | about 6 months ago | (#47128389)

I used to be called a tinfoil hatter. But Edward Snowden proved that even *I* wasn't paranoid enough.

You'll note that there has been a dearth on tinfoil hatter jokes since Snowden.

Re:This research should receive enormous funding. (1)

Anonymous Coward | about 6 months ago | (#47128595)

If I recall it right, the Invisible Boy used his power successfully, while only observed by a camera, at least I am pretty sure his power was used successfully!

Re:This research should receive enormous funding. (1)

Anonymous Coward | about 6 months ago | (#47128041)

From outside the hypothetical quantum box, the detector's observation of the quantum state is equivalent to saying that the detector has become entangled with the particle. So from the outside non-observer's point of view, the particle, the detector, and the cat are all still in a superposition state.

Entangelment and observation are basically the same thing. Observing a system causes you to be entangled with that system from the standpoint of anyone who tries to observe you. If you and the quantum box were placed in a sealed quantum room, then after you opened it, anyone outside the room would consider you to be in a superposition of morning/feeding your dead/alive cat.

Re:This research should receive enormous funding. (1)

bondsbw (888959) | about 6 months ago | (#47128067)

QM is one of those things I never get around to fully grasping because 1) I use my time for learning many other things that more directly apply to my life, and 2) I have attempted to understand it and just don't get it.

So, could someone please explain why we think that the wave function of a particle is believed to exist in superposition until it is observed (which causes the wave function to collapse)? Why don't quantum physicists assume that the wave function was always collapsed and never in a superposition? What evidence is there that the superposition existed, considering that any observation of such evidence collapses it?

Re:This research should receive enormous funding. (2)

skids (119237) | about 6 months ago | (#47128107)

The double slit experiment. Even when you slow down the rate of photons going through the slit so no two can possibly interfere, they still present a self-interference pattern. If the function was "already collapsed" it could not interact with itself.

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128449)

The double slit experiment. Even when you slow down the rate of photons going through the slit so no two can possibly interfere, they still present a self-interference pattern. If the function was "already collapsed" it could not interact with itself.

For me, at least, this indicates our understanding of QM is not complete. We just try to articulate our observations, but real explanations elude us.

Re:This research should receive enormous funding. (1)

barlevg (2111272) | about 6 months ago | (#47128485)

What do you mean by "understand?" This result--that all particles have wave-like natures and can do things like "interfere" with themselves, makes perfect sense to me, because it doesn't contradict anything in my observable world (where most of these effects get washed out). I just accept that our universe is inherently quantum mechanical, just as I accept that my hand is made of molecules which are made of atoms which are made of quarks and electrons, even though I have no "experience" dealing with things on that scale.

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128669)

That is the exact opposite of the result of that experiment though. An explanation eluded us until quantum mechanics, which then produced a strongly predictive explanation of the situation. That is as "real" as an explanation as you get out of science.

Re:This research should receive enormous funding. (3, Informative)

barlevg (2111272) | about 6 months ago | (#47128113)

Basically, we know that superpositions exist because we can perform experiments in which, if a particle were always in one state or the other, the results would be different. See: double-slit experiment [wikipedia.org] . If photons didn't exist in a superposition of states, then the distribution of light you'd get with the double slit would be the distribution you get from having one slit covered plus the one you'd get from covering the other one. But you don't--the distribution is completely different, which means that a single photon somehow travel though *both* slits and "interferes with itself." It's more than a little batshit.

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128135)

I still find the whole superposition idea as the option to have FILE_NOT_FOUND as a valid boolean value. A third state, a greyed out checkbox, an "I don't know" value so that you can make your math work out, but that doesn't make reality be that too. The cat will be dead, or it will be alive - not both, and it will put up a stench in the box, regardless of what your blackboard formulas say.

Re:This research should receive enormous funding. (1)

barlevg (2111272) | about 6 months ago | (#47128553)

Except that the math there works out completely differently.

See: double-slit experiment. [wikipedia.org] If photons didn't exist in a superposition of states, then the distribution of light you'd get with the double slit would be the distribution you get from having one slit covered plus the one you'd get from covering the other one. But you don't--the distribution is completely different, which means that a single photon somehow travel though *both* slits and "interferes with itself."

Re:This research should receive enormous funding. (1)

TheRaven64 (641858) | about 6 months ago | (#47128257)

That's the second time today you've been moderated up for a highly misleading explanation of Schroedinger's cat.

Re:This research should receive enormous funding. (5, Informative)

Charliemopps (1157495) | about 6 months ago | (#47128279)

I realize you were making a joke based on a perception common in popular culture, but the truth is that the Schrodinger's Cat paradox has a simple resolution: the cat *cannot* be both alive and dead because the detector (which detects whether the decay has occurred and which triggers the release of the poison if the decay occurred) collapses the wave function of the particle. There's no such thing as a passive detector. So while a subatomic particle could indeed exist in a superposition of "decayed" vs. "not decayed," the second you go about asking the particle whether it's decayed (that is, when you set up the detector), the wave function collapses, and no superposition is possible.

You're presenting your interpretation as fact, and it's not. It's a possible scenario, but this thought experiment is designed explicitly to show a paradox that we have yet to resolve. What you describe is the "Copenhagen interpretation" which was proposed by Niels Bohr, Werner Heisenberg and others in 1924 to 1927. It states that quantum states are not fixed but probabilities. Just as you said, once any measurement is made the wave function collapses and the state is fixed in the classical sense. If this interpretation is true, then you are correct. But there are many other interpretations that have any equally valid chance of being correct.

In the "Many-Worlds" interpretation, the cat really is both alive and dead. When you open the box you become entangled with the cat (not literally, that would hurt) and one version of you perceives it as alive and another perceives it as dead. Both results occur, you experience both, but you remain unaware of your duplicate and he of you.

Einstein himself supported an entirely different interpretation called the "Ensemble interpretation" which basically just makes the entire thought experiment irrelevant. It's wacky and hard to explain so I'll just link to it: http://en.wikipedia.org/wiki/E... [wikipedia.org]

Anyways, I recommend reading up on Schrödinger's cat via Wikipedia or some other source. You're only incorrect in that you thought your explanation was the only one.

Oh, and full disclosure, I'm not a scientist, I just find this stuff incredibly interesting. Also it makes me sound smart at parties. Actually I don't get invited to parties... they say I ramble on about nonsense. Thank God for the many worlds theory... at least I'm popular somewhere.

Re:This research should receive enormous funding. (2)

barlevg (2111272) | about 6 months ago | (#47128583)

You're presenting this response as if the Copenhagen Interpretation were not still the standard interpretation of QMech nearly a century after its formulation. In all the academic circles in which I've run (I have a Ph.D in physics, although my field was pretty far from quantum mechanics), Many World is considered an interesting idea with little practical consequence, and almost everything Einstein said regarding Quantum Mechanics has turned out to be disproved (though I'm not familiar with this specific interpretation).

Sorry, but that is just incorrect (2, Insightful)

Anonymous Coward | about 6 months ago | (#47128295)

Unfortunately this got modded up to +5 quickly, but is completely wrong.

. There's no such thing as a passive detector.

A larger part of quantum mechanics is there is no such thing as any interaction being passive. You're detector could consist of a photon bouncing off of a particle or the interaction between two particles. Until you make a measurement on that second particle, or it interacts with the environment, then you've created an entanglement between the detecting particle and the thing being measured. Any dependent interaction within a sealed system, whether called a detector or not, results in an entanglement of states, not breaking the superposition.

If instead we accepted what is said in the parent post as true, then entanglement could not exist, and you could go as far as to undermine all of quantum mechanics by finding issues with Bell's inequality, etc.

Re:Sorry, but that is just incorrect (1)

barlevg (2111272) | about 6 months ago | (#47128621)

It's true, I might have glossed over some of the subtleties, but my point with that line is that people think of observation and detection as a passive event when it's anything but, and not for any sort of mysterious "the mind makes it so" bullshit but because when you're looking at the wall in front of you what's actually happening is that photons are hitting the wall, bouncing off (or being absorbed and re-emitted--though I got chided for saying something similar about this earlier) and being collected in your eye. Without the stream of photons hitting the wall, you'd have no way of knowing it was there (extend photons to other force-mediating particles).

Re:Sorry, but that is just incorrect (0)

Anonymous Coward | about 6 months ago | (#47128769)

Right, but as with a lot of QM stuff, you just have to be careful not to go too far with explanations, otherwise you overemphasize something that least to wrong conclusions. There is a lot of junk that comes from misunderstanding what an "observer" is in QM when it just referring to an interaction. But a key point is that it is an interaction with the outside of the system under consideration, whereas interactions within a system are being accounted for.

I'm sure there is some software analogy that amounts to interaction with the outside allows for GIGO scenarios to be analogous to decoherence in the case of noise, or for collapse in specific cases where interactions are "sanitized" like proper access to a database. It comes down to not being able to know or have limited control over interactions with the outside world, and some interpretations try to quantify this a little better in terms of how messy something has to be before it isn't a well described or understood system.

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128693)

So what is the part in the detector (made out of quantum particles!) which selects exactly one of the outcomes? (And don't say "decoherence", because decoherence is only responsible for removing the interference, not for actually selecting a single output.)

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128007)

Forget QT specifically and think of this as one step towards mastering entanglement in general. How about the possibility of generating weirdly correlated transactions across the globe that give traders an advantage?

Re:This research should receive enormous funding. (1)

Mr0bvious (968303) | about 6 months ago | (#47128049)

Please excuse my absolute ignorance, but I was under the impression that classical information channel was only required to transmit one of the entangled photons. If one of the entangled photons (or what ever it is that is entangled) was transported elsewhere (truck, fiber optics, what-not) the two entangled would still maintain the same state (spin etc) and information could then be transmitted faster than light by changing the state of one and reading the state of the other.

I'm sure I just displayed my ignorance and lack of any understanding of QT, but there are sure to be others with this same understanding so it may be worth while pointing out where I've got this wrong.

Is your last sentence "You cannot do that with classical means, because you'd need to measure the state, thereby collapsing it into a classical state." the reason why this does not work?

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128115)

You can't even know the state without collapsing the entanglement, so you obviously can't change the state of one of the entangled particles to a known state before disentangling them.

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128371)

I was watching an interview with a very prestigious theoretical physicist when he started talking about some research he's been closely watching where they are able to entangle two photons, send one several kilometers away, then somehow entangle the remaining photon with an already measured classical photon. Entangling the quantum photon with the classical photon causes the quantum photon to take on the opposite properties of the classical one, which in turn causes the other quantum photon to take on the opposite properties of that quantum photon, which means you now have the exact original properties of the classical photon.

He said that this is real teleportion of real information. The problem is doing this destroys the state original classical photon, leaving it effectively random. But if you assume a given photon is its state, then you didn't destroy the photon, you teleported it. You still need to wait for the one quantum photon to travel to the destination via classic space time.

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128547)

You've basically just described quantum teleportation, what the article is about, etc. Except you missed one important part. When you interact half of the entangled pair with the state/photon you want to teleport, the entangled photon doesn't adopt the opposite of the "classical" one, but instead adopts a random transformation of the state you want to teleport. You can't predict which transformation it chooses, but by measuring your half of the entangled system, you can figure out which one randomly resulted. You then classically tell the person with the other half of the entanglement which transformation happened, they can undo that, and get a copy of the state you were sending (at no point is a measurement of the state being sent made though). You can send the other half of the entangled pair ahead of time, ignoring practical constraints, and let it just sit somewhere far away until you need it. The waiting involve is waiting for the classical signal to get there so the other person knows what they need to do to get the teleported state back instead of just a random state.

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128779)

One way to think of it is that on teleportation, the quantum information gets encrypted with a random classical key, and the classical key is handed to the sender. The receiver cannot decrypt the teleported state until he receives the classical key. Which cannot be sent faster than light.

Re:This research should receive enormous funding. (1)

skids (119237) | about 6 months ago | (#47128161)

It basically boils down to this: you have to send point B the data about what you did at point A for the reading you made at point B to be interpreted in any meaningful fashion. That data travels in a classical fashion so you don't know what your reading at point B actually means until after the light carrying the data from point A has arrived. Once the data are combined, they become actual information.

Not useful for exceedind the speed of light under currently accepted theory, but very useful for cryptography because only you have the reading from point B and both peices of data are needed to get the information, so someone stealing the classically transported data is still missing a part.

Re:This research should receive enormous funding. (2)

rgbatduke (1231380) | about 6 months ago | (#47128645)

Please excuse my absolute ignorance, but I was under the impression that classical information channel was only required to transmit one of the entangled photons. If one of the entangled photons (or what ever it is that is entangled) was transported elsewhere (truck, fiber optics, what-not) the two entangled would still maintain the same state (spin etc) and information could then be transmitted faster than light by changing the state of one and reading the state of the other.

Information cannot be transmitted faster than light as far as we know in standard physics today (barring extreme relativistic things like white or black holes and I doubt even those unless/until experiment verifies any claim that they can).

Quantum theory doesn't get around it. You cannot choose the direction to "collapse" or "change the state" of one of the two entangled spins, because the instant you measure it, it "collapses". You might now be able to predict the state of the other end of the channel, but the person there can't because he doesn't know what you measured, so if he measures up or down when he tries (again, supposed "collapsing the wavefunction") he won't know what you measured at your end or (since the two spins are no longer entangled as soon as a measurement is made at either end) what you do to it subsequently.

But the real problem (the "paradox" bit of EPR) is much worse than that. Suppose the two "entangled" electrons are separated by some distance D. Non-relativistic naive stupid quantum theory states that when one of the two electrons is measured, the wavefunction of the whole thing collapses. But suppose that D is nice and large -- in gedanken experiments we can make it a light year, why not? In the "rest frame of the Universe" (the frame in which the cosmic microwave background has on average no directional doppler shift) experimenters on both ends simultaneously perform a measurement of the spin state of the two electrons. This (simultaneity) is a perfectly valid concept in any given frame but is not a frame invariant concept. Neither is temporal ordering a universally valid concept. But given a simultaneous measurement of the two spins, which measurement causes the wavefunction to collapse and determines the global final state, given that the entropy of their measuring apparatus (which is responsible for the random phase shifts that supposedly break the entanglement, see Nakajima-Zwanzig equation and the Generalized Master Equation) is supposedly completely separable and independent?

By making D nice and large, we have a further problem. I said that the measurements were simultaneous in "the rest frame" (and even gave you a prescription for determining what frame I mean), but that means that if we boost that coordinate frame along one direction or the other, we can make either measurement occur first! That is, suppose the spins are in a singlet spin state so that if one is measured up (along some axis) the other must be measured down. Suppose that in frame A, spin 1 interacts with its local measuring apparatus first and is filtered into spin down. This interaction with its local entropy pool -- exchanging information with it via strictly retarded e.g. electromagnetic interactions -- supposedly "transluminally", that is to say instantaneously in frame A -- "causes" (whatever you want that word to mean) spin 2 in frame A to collapse into a non-entangled quantum state in which the probability of measuring its spin up in that frame some time later than the time of measurement in frame A is unity. In frame B, however, it is spin 2's measurement that is performed first, and as the electron interacts with its entropy pool you have a serious problem. If you follow any of the quantum approaches to measurement -- most of them random phase approximation or master equation projections that assume that the filter forces a final state on the basis of its local entropy and unknown/unspecified state -- it cannot independently conclude that the spin of this electron is down -- the measurement will definitely be up -- because in frame A the measurement of spin 1 has already happened. In no possible sense can the measurement of spin 2 in frame B in the up state "cause" spin 1 to be in a state that -- independent of the state of its measurement apparatus -- will definitely be measured as spin down. Otherwise you have (in frame A) to accept the truth of the statement that a future measurement of the state of spin 2 is what determines the outcome of the present measurement of the state of spin 1. Oooo, bad.

The problem, as you can see, is that relativity theory puts some very stringent limits on what we can possibly mean by the word "cause". They pretty much completely exclude any possible way that the statement "measuring spin 1 causes the 1-2 entangled wavefunction to collapse" can have frame-invariant meaning, and meaning that isn't inertial frame invariant in a relativistic universe isn't, that is, it is meaningless. We can only conclude that the correlated outcomes of the measurements was not determined by the local entropy state of the measurement apparatus at the time of the measurements.

Fortunately, we have one more tool to help us understand the outcome. Physics is symmetric in time. Indeed, our insistence on using retarded vs advanced or stationary (Dirac) Green's functions to describe causal interactions is entirely due to our psychological/perceptual experience of an entropic arrow of time, where entropy is strictly speaking the log of the missing/lost/neglected information in any macroscopic description of a microscopically reversible problem. That's the reason the Generalized Master Equation approach is so enormously informative. It starts with the entire, microscopically reversible Universe, which is all in a definite quantum entangled state with nothing outside of it to cause it to "collapse". In this "God's Eye" description, there is just a Universal wavefunction or density operator for a few gazillion particles with completely determined phases, evolving completely reversibly in time, with zero entropy. One then takes some subsystem -- say, an innocent pair of unsuspecting electrons -- and forms the e.g. 2x2 submatrix describing their mutually coupled state. Note well that both spins are coupled to every other particle in the Universe at all times -- this submatrix is "identified", not really created or derived, within the larger universal density matrix, and things like rows and columns can be permuted to (without loss of generality) bring it to the upper left hand corner where it becomes the "system". The submatrix for everything else (not including coupling to the spins) is similarly identified.

Nakajima-Zwanzig construction treats this second submatrix statistically because we cannot know or measure the general state of the Universe and have a hard enough time measuring/knowing the state of the 2x2 submatrix we've identified as an "entangled system". It projects the entirety of "everything else" into diagonal probabilities (by e.g. a random phase approximation, making the entropy of the rest of the Universe classical entropy) and then treats the interaction of these diagonal objects with the spins as being weak enough to be ignored, usually, except of course when it is not. It is not when e.g. the spins emit or absorb photons from the rest of the Universe (virtual or otherwise) while interacting with a measuring apparatus or the apparatus that prepared the spins. Because we cannot track the actual fully entangled phases of all the interactions in this enormous submatrix and with the submatrix and the system, the best we can manage is this semiclassical interaction that takes entropy from "the bath" (everything else) and bleeds it statistically into "the system".

In this picture (which should again be geometrically relativistic) there was never any question as to the outcome of the "measurement" of the entangled spin state by the remotely separated apparati, and furthermore, while the NZ equation is not reversible, we can fully appreciate the fact that if we time reverse the actual density matrix it approximates, the two electrons will leap out of the measuring apparatus, propagate backwards in time, and form the original supposedly quantum entangled state because it never left it -- it was/is/will be entangled with every particle that makes up the measuring apparatus that would eventually "collapse" its wavefunction over the entire span of time.

Note that in this description there is no such thing as wavefunction collapse, not really. That whole idea is neither microreversible nor frame invariant. It describes the classical process of measurement of a quantum object, where the measuring apparatus is not treated either relativistically correctly or as a fully coupled quantum system in in a collectively definite state in its own right. It isn't surprising that it leads to paradoxes and hence silly statements that don't really describe what is going on.

This is a more detailed discussion of the very apropos comment above that similarly resolves Schrodinger's Cat -- the cat cannot be in a quantum superposition of alive and dead because every particle in the cat and the quantum decaying nucleus that triggers the infernal device is never isolated from every other particle in the Universe. The cat gives off thermal radiation as it is alive that exchanges information and entropy with the walls of the death chamber, which interact thermally with the outside. The instant the cat dies, there is a retarded propagation of the altered trajectories of all of its particles communicated to the outside Universe of coupled particles, which were in turn communicating/interacting with all of the particles that make up "the cat" and with the nucleus itself and with the detector and with the poisoning device both before, during, and after all changes. the changes never occur in the "isolation" we approximate and imagine to simplify the problem.

Hope this helps.

rgb

Re:This research should receive enormous funding. (1)

ortholattice (175065) | about 6 months ago | (#47128309)

What you can do is use quantum teleportation to "transmit" (in a manner of speaking) a real (or complex) number, i.e. a quantum superposition, which in theory could contain infinite information, by using only a couple of classical bits. This real number can't be observed directly - you can only tell whether it's less than or greater than a specified number by appropriately designing your observation - but until you observe it, it can be further processed in its full precision as a superposition at the receiver end using quantum operations. What you can do with this internal (uncollapsed) infinite information is up to you, e.g. as part of a quantum factoring or search algorithm, until you finally collapse it and read out some yes/no answer. All in theory of course; in practice you have noise and other sources of error.

Actually Faster than light travel does occur (1)

Anonymous Coward | about 6 months ago | (#47128477)

And at the atomic and subatomic level, quantum entanglement does allow for information (in this case information about the atom's state) to be transferred superluminally. It seems nature has been doing that since at least the beginning of the universe. That mankind can't figure out how to use it to transmit information FTL isn't relevant.

Eventually though we'll figure out how to do it and our understanding of physics will be broadened beyond its currently primitive state.

And on the subject it appears that the speed of light, c, only exists because photons are absorbed and remitted as light passes through the quantum vacuum where virtual particles come into and go out of existence. Recent research indicates that here [arxiv.org]

Furthermore based on such research it appears that without the "traffic" of virtual particles as light travels from point A to point B there wouldn't be any delay in transmission at all, that one would have instantaneous transmission of information. Which is exactly what one sees with quantum entanglement.

Actually Faster than light travel does occur (0)

Anonymous Coward | about 6 months ago | (#47128529)

So, remove virtual particles and let light rip.

How?

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47128655)

Don't worry. They'll just allow placing quantum orders, and then when the classical information arrives, they can be fixed up on the fly. ;-)

Re:This research should receive enormous funding. (0)

Anonymous Coward | about 6 months ago | (#47127941)

Can you imagine the boner the high speed traders would have if someone figured out a way to communicate information from New York to Chicago or London instantaneously?

I doubt we could handle it. HFT hasn't exactly been stable today. I really don't think we need to keep feeding that beast.

Now porn on the other hand...

Re: This research should receive enormous funding. (1)

ewanm89 (1052822) | about 6 months ago | (#47128201)

'Ye cannae change the laws o' physics'

Classical information is still limited by the speed of light. Quantum teleportation can not be used for traditional communications.

Re: This research should receive enormous funding. (1)

Chris Mattern (191822) | about 6 months ago | (#47128293)

Quantum teleportation can not be used for traditional communications.

Quantum teleportation can not be used for traditional communications *by itself*. It is possible to set up a situation where you combine QT with traditional transmission so that both the QT and the transmission are required to receive the data. Relativity is observed, as you don't have the data until you get the speed of light transmission. But you get QT's security, as intercepting just the tranmission won't yield anything.

Re:This research should receive enormous funding. (1)

dywolf (2673597) | about 6 months ago | (#47128453)

they would fight it because one of hte most popular HFT scams involves exploiting the lag time between different markets.

magic? (0)

Anonymous Coward | about 6 months ago | (#47127865)

teleportation sounds like magic to me. can anybody explain?

Re:magic? (1)

Victor_0x53h (1164907) | about 6 months ago | (#47127951)

Like I'm 5, please.

Re:magic? (1)

barlevg (2111272) | about 6 months ago | (#47127965)

So this isn't really my field, but as I understand it [wikipedia.org] (lol at their definition of "non-technical") the idea is that you have two "entangled" particles, separated by some arbitrary distance. If you change something about the first particle, and then send a signal to the second particle (this signal being composed of "classical" information, basically 1s and 0s), then you can make it so that the second particle is an exact copy of the first. Right now they're just at the "qubit" level, but presumably if this scales, you could take a large physical object (a person) and copy them on a quantum level to a distant location by sending a signal of "classical" data. I'm not sure how you go about creating the "entangled you," though.

Re:magic? (2)

MRe_nl (306212) | about 6 months ago | (#47127985)

The whole universe is local. It turns out all spells are actually ranged touch attacks. This will cause a massive disruption in the Unseen University at about lunch-time.

I think this was reported the other day (3, Funny)

jareth-0205 (525594) | about 6 months ago | (#47127899)

Re:I think this was reported the other day (1)

barlevg (2111272) | about 6 months ago | (#47127917)

Quantum teleportation isn't "simultaneous." It appears to require the transmission of classical "bits" of information, which is limited to the speed of light. No causality- or Eisenstein-breaking paradoxes here.

Re:I think this was reported the other day (0)

Anonymous Coward | about 6 months ago | (#47128015)

Quantum teleportation isn't "simultaneous." It appears to require the transmission of classical "bits" of information, which is limited to the speed of light. No causality- or Eisenstein-breaking paradoxes here.

True, but we've achieved great strides with multiplexing/channeling. Who knows if this could give birth to a new form in which we could push traditional "bits" in a different way.

Re:I think this was reported the other day (0)

Anonymous Coward | about 6 months ago | (#47128053)

No causality- or Eisenstein-breaking paradoxes here.

Only Einstein can be disproven. Causality is a fundamental part of science.

Re:I think this was reported the other day (0)

Anonymous Coward | about 6 months ago | (#47128539)

Causality is a fundamental part of science.

We'll see about that. I predict that notion of causality will have to change, or ... well, entangle, like absolute space and absolute time had. I have a hunch that causality and information are two sides of a same coin, and that this is exactly what makes apparent paradoxes.

Re:I think this was reported the other day (0)

Anonymous Coward | about 6 months ago | (#47128683)

Causality is a hypothesis, unfortunately while we have evidence for causality, it is not a testable hypothesis.

The other hypothesis, the quantum erasure hypothesis, posits that entropy reducing and entropy increasing state changes happen with equal probability, but entropy reducing state transitions erase information about the higher entropy state, and thus we have no evidence and are logically forbidden from having evidence of entropy reducing. This too is an untestable hypothesis.

The quantum erasure hypothesis is appealing, as it makes some of the stranger effects we observe in quantum confined systems more readily explainable. It's unappealing because it disagrees immensely with out own memories and intuition, and our sense that we are progressing linearly through time and never "backing up", but it's important to consider that our memories and intuition, and our senses are part of the state of this quantum system and cannot progress without the entropy gradient that we observe.

There is a third hypothesis, a sort of combination between the two extremes, in which some quantum operations are reversible (for an arithmetic example A+B -> B' is reversible by B'-A -> B) where-as others are not (keeping with arithmetic examples A*B -> B' is not reversible when either A or B is zero), and thus the reversible operations are applied in equal probability to their inversions, but irreversible operations are applied occasionally which freeze us into a higher entropy state. Unfortunately while appealing, and having a nice analogy in Von Neumann arithmetic, I'm not aware of any experiment that demonstrates these two classes of quantum operations or any quantum theory that formalises this arrangement.

Thus we have evidence for causality that is equally well explained by quantum erasure, we cannot have evidence for quantum erasure and observed causality does not falsify quantum erasure, and we have no evidence for the third theory, let's call it finalisation, even though it ought to exist.

There are however subtle differences, a quantum computer ought not to be feasible in causal reality and as of yet we have no evidence of feasible quantum computation (by this I mean a quantum computer than can calculate faster than relativistic limits dictate). So if we manage to build a hyper-relativistic quantum computer (my money's on not), we either have to rule out relativity or rule out causality.

-puddingpimp

Erroneous actually... (0)

Anonymous Coward | about 6 months ago | (#47128581)

Because at the atomic and subatomic level, quantum entanglement does allow for information (in this case information about the atom's state) to be transferred superluminally. It seems nature has been doing that since at least the beginning of the universe. That mankind can't figure out how to use it to transmit information FTL isn't relevant.

Furthermore, on the subject of casuality, if one can observe information being transmitted at the atomic/subatomic level FTL then there wouldn't be any causality violations as one would be able to see the cause/effect phenomenon (whatever it happened to be) occur from start to finish superluminally.

The nonsense about causality violations only arises when one limits their thought experiment to viewing something as part luminally (light speed) and part superluminally. If you have a different perspective (i.e., seeing the experiment in its totality) you'll realize there are no causality violations.

I'm a bit surprised theoretical physicists don't realize something that basic.

Re:I think this was reported the other day (1)

neilo_1701D (2765337) | about 6 months ago | (#47127999)

You utter bastard.

As if I didn't have enough keeping up with XKCD, now you bring this rather funny comic to take my attention.

May the fleas of a kilocamel infest your armpits.

Re:I think this was reported the other day (2, Funny)

Anonymous Coward | about 6 months ago | (#47128089)

And may the comments in your code always be one word too long to fit on a single line.

Re:I think this was reported the other day (1)

abies (607076) | about 6 months ago | (#47128087)

I liked Terry Pratchett version more. It was about reign - when king dies, his successor becomes a king immediately. Idea of modulating the waves by torturing kings at near-death state was also mentioned.

Headline (2)

slapout (93640) | about 6 months ago | (#47127901)

"Scientists Find Method To Reliably Teleport Data"

Scientist found the internet?

Re:Headline (0)

Anonymous Coward | about 6 months ago | (#47127975)

They said "reliably" ! Can't be the internet

Re:Headline (1)

Anonymous Coward | about 6 months ago | (#47128093)

You're confusing UDP with TCP.

Re:Headline (1)

barlevg (2111272) | about 6 months ago | (#47127977)

The key is that it's not classical data, as in 1s and 0s, it's "quantum" data, as in, the very fuzzy states of physical particles.

Re:Headline (0)

Anonymous Coward | about 6 months ago | (#47128541)

I'm a fuzzy state of physical particles! Physical particles and fuzz everywhere!

Teleportation is misleading, random numbers better (0)

Anonymous Coward | about 6 months ago | (#47127913)

Teleportation is misleading because in practice (for applications) they just created two random number generators that has been seeded with same value.

Meaning simply: they now have two things that spews same random numbers each time they ask.

As with any other random number generator, in order to use the duplicate randomness you have to have "classical connection" meaning normal data link.

Re:Teleportation is misleading, random numbers bet (1)

fuzzyfuzzyfungus (1223518) | about 6 months ago | (#47127949)

Hmm, sounds like the NSA's next proposal for a 'totally secure, like for realz guys!' RNG standard...

Evil high frequency traders everywhere are salivat (0)

Anonymous Coward | about 6 months ago | (#47127939)

And calling up their techie accomplices to find out how to be first to bat on this.

I want to teleport instead of download. (1)

martiniturbide (1203660) | about 6 months ago | (#47127945)

That will make our internet faster and will end the Comcast/Netflix deal.

Re:I want to teleport instead of download. (1)

jellomizer (103300) | about 6 months ago | (#47128011)

Well if you can get a point to point communication without the need of a middle man ISP. Yes you could end the comcast/nextflix deal. Heck Comcast itself will be gone.

Good news all around.

Re:I want to teleport instead of download. (1)

geekmux (1040042) | about 6 months ago | (#47128037)

That will make our internet faster and will end the Comcast/Netflix deal.

I'd be careful with wild cards. You could fill hard drives in seconds with that.

And whatever you do, do NOT teleport at work. It would be a bitch to explain to the boss why the corporate file server became instantly full of porn.

Even I can beat the old way (1)

stewsters (1406737) | about 6 months ago | (#47127963)

only one of every 100 million attempts succeeded

I can beat that in software.

bool getMessage() {
return rand() % 2 == 1;
}

Re:Even I can beat the old way (1)

barlevg (2111272) | about 6 months ago | (#47127991)

The information being transmitted isn't binary 1s and 0s but full quantum states. See: qubit [wikipedia.org] .

Is quantum computing a fad? (0)

Anonymous Coward | about 6 months ago | (#47127967)

I'm still not sold on why we need to do all this stuff with quantum computers. Sounds like a big waste of money to me.

How fast is the data transmitted? (0)

Anonymous Coward | about 6 months ago | (#47127981)

I mean, is it faster than the speed of light?

I thought it was impossible to transmit information using entangled particles? (Because if you try to set the spin, or another property, on the first particle, it breaks the entanglement).

Why not 1000 km? (2)

NotDrWho (3543773) | about 6 months ago | (#47127983)

If it's real "quantum entanglement," that should be not different than 3m or 1km.

Re:Why not 1000 km? (1)

abies (607076) | about 6 months ago | (#47128045)

How difficult is it to drop a rock? Easy. Can you please drop a rock from 50km high? After all, dropping a rock is not different if it is 1m or 50km high.

They need to entangle both sides of the communication from single place and this is quite hard longer the distance. Moving it afterwards is also quite difficult, it is not a small, robust device you can carry in your pocket.

Re:Why not 1000 km? (0)

Anonymous Coward | about 6 months ago | (#47128269)

Can you please drop a rock from 50km high?

I'll give Virgin Galactic a ring to see if they can accommodate this when I take my flight to space [slashdot.org] .

Re:Why not 1000 km? (1)

aicrules (819392) | about 6 months ago | (#47128065)

If they were 100% sure how to use quantum entanglement, then yes. But they're still trying to figure it out, including whether anything they try is ACTUALLY that or some other thing happening.

And... proving that you can't fool Mother Nature.. (1)

Miamicanes (730264) | about 6 months ago | (#47128017)

Quantum data transfer will probably end up succumbing to the same kind of catch-22/gotcha that plagues realtime digital filtering of analog waveforms...

a) Analog filtering introduces phase changes due to delays. When digitally-filtering a waveform, the length of time you have to sample it to get enough to analyze and transform ends up introducing basically the same phase shift an analog filter would have caused.

b) Quantum data transfer has "1 in 100 million" odds of actually working for any particular attempt. Obviously , lots of forward error correction will be needed to both detect and fix errors. My prediction is that the time the required error-correction overhead adds to the transmission time will end up being basically equal to the time it would have taken to transmit the data at the speed of light.

c) In both cases, the limit will apply primarily to realtime uses. Using the audio example, if you try to apply a digital high-pass/low-pass filter to audio for something like a subwoofer, you'll basically create the same phase shift you would have had anyway... but if you have the luxury of buffering playback so that you have time to completely analyze the signal & can delay the OTHER signals to bring them back into temporal alignment with the filtered signal, you can enjoy the best of both worlds... infinite-slope filtering with zero induced phase shift. In the context of quantum data transfer, it will fail at the goal of "faster than light" throughput, but might nevertheless find utility as a way to transport data in non-realtime under circumstances that would render "normal" electromagnetic radio modulation schemes unusable.

Could the soul survive? (1)

Rik Sweeney (471717) | about 6 months ago | (#47128023)

I still don't think teleporting would leave the soul intact. To the observer, the result may act and behave in the same way before the teleportation took place, but I wonder if it would be the same person?

Re:Could the soul survive? (1)

Primate Pete (2773471) | about 6 months ago | (#47128073)

I'm pretty sure electrons don't have souls. I'm fairly confident that I don't, either.

So maybe this is on physics/engineering problem we can ignore.

Re:Could the soul survive? (0)

Anonymous Coward | about 6 months ago | (#47128423)

It's not our fault you're a ginger.

Re:Could the soul survive? (1)

skids (119237) | about 6 months ago | (#47128239)

That philisophical debate hinges around whether the essence of the object being teleported must be destroyed.

Re:Could the soul survive? (0)

Anonymous Coward | about 6 months ago | (#47128437)

That question depends on what the soul really is. Right now we have no idea. We deduce that it's a meta-component of us, of our organic robot bodies, but we don't know what it is, where it is, how to measure it if we ever stumble upon it. We're no even sure our bodies would be anything more than meat vegetables should our soul be separated from our bodies. Is consciousness our soul? Is it a derived property from us having a soul?

Now, on the bright side, if we do ever teleport living things, this question that bothered people since they discovered thought, we may get closer to finding an answer. If everything we teleport ends up dead even though we know with 100% certainty that we teleported every particle and its state from A to B, with no misalignment, no alteration, no extra or missing electrons or atoms, then it might be clear: the soul got detached. If the result does bark the same as the source did, then the soul is either linked to some sort of hash (in which case one should really try to make two identical copies and see what happens), or the question will remain unanswered (if no matter how many clones you make, they will start identical and then diverge as independent individuals). Cloning could still unlink the original soul and link new ones into each clone. Would anybody, including the clones, even perceive anything like that?

Maybe one should clone Guinan, because she was the only one to feel something different when the Enterprise C decided to make an unannounced visit [memory-alpha.org] . Maybe the sole is just the pilot, and its only perception is through memories and sensors. Like a CPU, if you put it to sleep and change the memory banks underneath it with ones that contain completely different information, one might not realise that this has happened when awaken again.

Re:Could the soul survive? (1)

Herder Of Code (2989779) | about 6 months ago | (#47128543)

Or how about this crazy thought? There's no detachment and re attachment of souls because we don't have a magical out of body spirit presence where our mind is stored :).

the discourse must have been riveting (1)

nimbius (983462) | about 6 months ago | (#47128109)

scientific journal: earlier tests unsuccessful as we've managed to teleport ryans carbonara pasta lunch into the aegean sea (could not recover.)
Update: telimetry meeting at 2:00 to discuss experimental teleportation of a cat 8 miles above the research chamber. projects will no longer be colloquially referred to as 'operation cat splat'
informational: research staff will immediately discontinue teleportation of chicken vindaloo from the west end of town. building maintenance will be on site this afternoon to correct the eleven pounds of vindaloo in the break room water cooler

Where is the money (1)

EngineeringStudent (3003337) | about 6 months ago | (#47128159)

I think they are working to answer a good question, but not necessarily a high value question. Why does distance matter? Scientific inquiry is good, but the goal is return of value to humanity. If you worked on making computer parts that could transmit information faster and more reliably over a very short distance, somewhere between a meter and a millimeter, then you could plausibly improve the lives of most of the folks on the planet, or at least enable them to check slashdot or facebook more cheaply.

eat it (1)

slashmydots (2189826) | about 6 months ago | (#47128271)

I've been having morons reply to my posts for years about how information can't travel faster than the speed of light. It can with quantum technology. If the particles are technically the same particle, they're synced and information isn't "traveling" and "distance" necessarily. In fact, you're all so incorrect that even NASA believes you're wrong and tried to do a quantum entanglement experiment between Earth and the ISS recently. So take this article, shove it up your ass, and stop saying I'm wrong.

Finally a decent use for diamonds (0)

Anonymous Coward | about 6 months ago | (#47128427)

About time someone made diamonds into computers, now those useless lumps of expensive glass have a use.
Until now diamonds have only been an expensive way to take advantage of your girlfriend, or as a way to cut into really hard surfaces.

1 (presumably small) diamond per Qbit, from memory we need at least 8 Qbits to make anything useful.

Your move De Beers.

If information can't be sent faster than C..... (2)

mark-t (151149) | about 6 months ago | (#47128709)

.... then I'm not sure what the real difference is between teleporting data and simply sending it. Can somebody please explain?

The data does not get transmitted across distances (1)

0x537461746943 (781157) | about 6 months ago | (#47128791)

After reading a bunch of articles on this it seems like the general public really doesn't understand that the data does not get transmitted across distances. The encoding of the data was done at entanglement time.

You take 2 envelopes. Write the word UP and DOWN on two separate pieces of paper, mix them up and put them in an envelope. Send them to two different locations. Open one envelope and you will have the opposite reading in the other envelope which could be miles or light years away. As far as transmitting data this is more inline with what is happening.
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