Unconditional quantum teleportation?

[annnnoid]

Quantum information transfer confirmed. Einstein wrong (didn’t he say it couldn’t happen?). Is this news? If this experiment turns out to be reliable, what explains it? How does it happen?

http://hansonlab.tudelft.nl/teleportation/

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

 

[Roboramma]

I should note I'm just someone interested in this and don't have any expertise. That said, my understanding:

Quantum information transfer confirmed.

That has been done before.

Einstein wrong (didn’t he say it couldn’t happen?).

Yep. But it was pretty damn insightful of him to even see the problem to begin with.

Is this news?

In so much as it appears to be another incremental step in better experimental design and possible future technological applications (see quantum computing), yes.

If this experiment turns out to be reliable, what explains it?

Entanglement.

How does it happen?

The states of the particles in one place are entangled with those in another. Note that classical information has to be transferred from location A to location B to make this teleportation possible.

 

[Dancing David]

The issue is that quantum entanglement will not lead to anything really useful. It usually is only over limited distances, very particular conditions. And as communication it has extreme limitations, in that codes would have to be arranged in advance and the the entangled bit moved to location.

 

[Crossbow]

Quantum information transfer confirmed. Einstein wrong (didn’t he say it couldn’t happen?). Is this news? If this experiment turns out to be reliable, what explains it? How does it happen?

http://hansonlab.tudelft.nl/teleportation/

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

So far, every time I have seen someone at JREF claim that 'Einstein was wrong', it has turned out that the JREF post was wrong as opposed to Einstein being wrong.

In this case, I saw a confirmed demonstration of information transfer using the quantum mechanics method of 'tunneling' done a few years ago.

 

[W.D.Clinger]

So far, every time I have seen someone at JREF claim that 'Einstein was wrong', it has turned out that the JREF post was wrong as opposed to Einstein being wrong.

In this case, Einstein seems to have been wrong.

 

[Crossbow]

In this case, Einstein seems to have been wrong.

The one paper was done in 1935.
The other paper was done in 1964.

Do you have anything more current?

 

[W.D.Clinger]

In this case, Einstein seems to have been wrong.

The one paper was done in 1935.
The other paper was done in 1964.

Do you have anything more current?

Many experimental tests have shown violations of Bell's inequality, which almost all physicists accept as experimental proof that Einstein was wrong about this. Every year, the results of several new experiments are published. Many of these new tests are designed to rule out some theoretical loophole that might be raised as an objection against previous experiments.

The links in that paragraph above will take you to Wikipedia articles that cite many references more recent than Bell's 1964 paper (which was theoretical in nature, not experimental).

 

[Farsight]

So far, every time I have seen someone at JREF claim that 'Einstein was wrong', it has turned out that the JREF post was wrong as opposed to Einstein being wrong.

That's how it usually is. When it comes to quantum mysticism, "Einstein was wrong" is a real attention getter. But when you look closely at what's been done, it's all will'o the wisp stuff. Like, quantum teleportation isn't teleportation. And you can't use it to send messages. As regards Bell, take a look at J.S. Bell's Concept of Local Causality by Travis Norsen:

"Many textbooks and commentators report that Bell's theorem refutes the possibility (suggested especially by Einstein, Podolsky, and Rosen in 1935) of supplementing ordinary quantum theory with additional ("hidden") variables that might restore determinism and/or some notion of an observer-independent reality. On this view, Bell's theorem supports the orthodox Copenhagen interpretation. Bell's own view of his theorem, however, was quite different. He instead took the theorem as establishing an "essential conflict" between the now well-tested empirical predictions of quantum theory and relativistic local causality. The goal of the present paper is, in general, to make Bell's own views more widely known and, in particular, to explain in detail Bell's little-known mathematical formulation of the concept of relativistic local causality on which his theorem rests..."

 

[annnnoid]

Entanglement.

The states of the particles in one place are entangled with those in another. Note that classical information has to be transferred from location A to location B to make this teleportation possible.

What do you mean by ‘classical information’?

How does ‘information’ travel instantaneously between two entangled objects? Presumably, the answer to this question has something to do with why Einstein didn’t like the whole idea.

The issue is that quantum entanglement will not lead to anything really useful. It usually is only over limited distances, very particular conditions. And as communication it has extreme limitations, in that codes would have to be arranged in advance and the the entangled bit moved to location.

What are the odds that…if you were around a 100 years from now…you would disagree with that conclusion?

Apparently they’re planning upping the ante. A kilometer or more.

What use is it? Is that why scientists do theoretical work? ...and because the question " how does that happen " may be rather significant in this particular case.

 

[Crossbow]

Many experimental tests have shown violations of Bell's inequality, which almost all physicists accept as experimental proof that Einstein was wrong about this. Every year, the results of several new experiments are published. Many of these new tests are designed to rule out some theoretical loophole that might be raised as an objection against previous experiments.

The links in that paragraph above will take you to Wikipedia articles that cite many references more recent than Bell's 1964 paper (which was theoretical in nature, not experimental).

Sorry, but I am still not sure what you are driving at.

That Wikipedia article has quite a few links in it, so please be more specific as to just which links (or links) show that Einstein was wrong.

Thanks.

 

[W.D.Clinger]

Many experimental tests have shown violations of Bell's inequality, which almost all physicists accept as experimental proof that Einstein was wrong about this. Every year, the results of several new experiments are published. Many of these new tests are designed to rule out some theoretical loophole that might be raised as an objection against previous experiments.

The links in that paragraph above will take you to Wikipedia articles that cite many references more recent than Bell's 1964 paper (which was theoretical in nature, not experimental).

Sorry, but I am still not sure what you are driving at.

That Wikipedia article has quite a few links in it, so please be more specific as to just which links (or links) show that Einstein was wrong.

Thanks.

In 1935, Einstein, Podolsky, and Rosen (EPR) published a theoretical paper arguing that quantum mechanics was incomplete. EPR believed the phenomenon known as quantum entanglement could be explained by so-called hidden variables that had yet to be discovered.

In 1964, John Bell proved that hidden variables as proposed by EPR would imply a certain inequality. If EPR (Einstein et al.) were right about quantum entanglement being explicable in terms of as-yet-undiscovered hidden variables, then Bell's inequality would hold.

Hundreds of experiments have shown that Bell's inequality does not hold. Therefore EPR (Einstein et al.) were wrong.

When Einstein said "God does not play dice with the universe", he was insisting there must be some deterministic account of quantum entanglement. There is: the Everett (or many-worlds) interpretation is deterministic. Einstein, however, thought a hidden-variables interpretation would work. He was wrong about that.

If you need to see an authority figure saying Einstein was wrong, see Steven Hawking's lecture asking Does God play Dice? and search for the word "Einstein".

 

[Crossbow]

In 1935, Einstein, Podolsky, and Rosen (EPR) published a theoretical paper arguing that quantum mechanics was incomplete. EPR believed the phenomenon known as quantum entanglement could be explained by so-called hidden variables that had yet to be discovered.

In 1964, John Bell proved that hidden variables as proposed by EPR would imply a certain inequality. If EPR (Einstein et al.) were right about quantum entanglement being explicable in terms of as-yet-undiscovered hidden variables, then Bell's inequality would hold.

Hundreds of experiments have shown that Bell's inequality does not hold. Therefore EPR (Einstein et al.) were wrong.

When Einstein said "God does not play dice with the universe", he was insisting there must be some deterministic account of quantum entanglement. There is: the Everett (or many-worlds) interpretation is deterministic. Einstein, however, thought a hidden-variables interpretation would work. He was wrong about that.

If you need to see an authority figure saying Einstein was wrong, see Steven Hawking's lecture asking Does God play Dice? and search for the word "Einstein".

Ok, thanks.

I think I see what you are saying now, and it is much like I expected.

Einstein did indeed say at one point that "God does not play dice with the universe" and Einstein did try his best to disprove Quantum Mechanics up until his death.

So if this is what you are referring, then you are indeed correct; Einstein (and some of the other people of his day) has been proven wrong in regards to his ideas about Quantum Mechanics.

 

[Farsight]

Einstein didn't try to disprove quantum mechanics up until his death. He was in on the ground floor. He just refused to accept quantum mysticism, wherein people say "quantum mechanics surpasseth all human understanding" or "it isn't classical, you can never hope to understand it". Instead he said it must be incomplete. Make sure you read In praise of weakness featuring work by Aephraim Steinberg and others. Here's an excerpt:

"There is no quantum world,” claimed Niels Bohr, one of the founders of quantum mechanics. This powerful theory, though it underlies so much of modern science and technology, is an abstract mathematical description that is notoriously difficult to visualize – so much so that Bohr himself felt it a mistake to even try... Only when we choose what to measure must the wavefunction “collapse” into one state or another, to use the language of the Copenhagen interpretation of quantum theory. Over the last 20 years, however, a new set of ideas about quantum measurement has little by little been gaining a foothold in the minds of some physicists. Known as weak measurement, this novel paradigm has already been used for investigating a number of basic mysteries of quantum mechanics. At a more practical level, it has also been used to develop new methods for carrying out real-world measurements with remarkable sensitivity. Perhaps most significantly in the long run, some researchers believe that weak measurements may offer a glimmer of hope for a deeper understanding of whatever it is that lies behind the quantum state".

And beware of woo-mongers peddling the multiverse.

 

[Crossbow]

Einstein didn't try to disprove quantum mechanics up until his death. He was in on the ground floor. He just refused to accept quantum mysticism, wherein people say "quantum mechanics surpasseth all human understanding" or "it isn't classical, you can never hope to understand it". Instead he said it must be incomplete. Make sure you read In praise of weakness featuring work by Aephraim Steinberg and others. Here's an excerpt:

"There is no quantum world,” claimed Niels Bohr, one of the founders of quantum mechanics. This powerful theory, though it underlies so much of modern science and technology, is an abstract mathematical description that is notoriously difficult to visualize – so much so that Bohr himself felt it a mistake to even try... Only when we choose what to measure must the wavefunction “collapse” into one state or another, to use the language of the Copenhagen interpretation of quantum theory. Over the last 20 years, however, a new set of ideas about quantum measurement has little by little been gaining a foothold in the minds of some physicists. Known as weak measurement, this novel paradigm has already been used for investigating a number of basic mysteries of quantum mechanics. At a more practical level, it has also been used to develop new methods for carrying out real-world measurements with remarkable sensitivity. Perhaps most significantly in the long run, some researchers believe that weak measurements may offer a glimmer of hope for a deeper understanding of whatever it is that lies behind the quantum state".

And beware of woo-mongers peddling the multiverse.

Thanks much!

This is a very good way to look at the issue.

 

[GnaGnaMan]

The issue is that quantum entanglement will not lead to anything really useful. It usually is only over limited distances, very particular conditions. And as communication it has extreme limitations, in that codes would have to be arranged in advance and the the entangled bit moved to location.

That seems rather dubious given that entanglement based technology is already in existence.

ETA: See, for example, this press report: http://www.economist.com/blogs/babbage/2012/02/quantum-cryptography

 

[GnaGnaMan]

Einstein wrong (didn’t he say it couldn’t happen?).

I doubt he said that. He believed that quantum physics was incomplete. He believed that there should be what's now called a hidden variable theory. This has since been shown to be false.
However, if it had been true then that would imply that there really was no such thing as quantum information (and nothing impossible about transferring what information there is).

 

[Reality Check]

Einstein didn't try to disprove quantum mechanics up until his death.

No one says that, Farsight.
Everyone knows that Einstein did not think that QM was complete - that there were hidden variables that made it deterministic.
Read W.D.Clinger's post:

In 1935, Einstein, Podolsky, and Rosen (EPR) published a theoretical paper arguing that quantum mechanics was incomplete.

I think that Einstein's opinion is more fully expressed in this 1942 quote:

It seems hard to sneak a look at God's cards. But that He plays dice and uses "telepathic" methods... is something that I cannot believe for a single moment.

Einstein has been shown to be wrong by the many experiments that show that QM cannot be a hidden variable theory. The topic of this thread is those ""telepathic" methods" so we could say that Einstein was wrong twice .

 

[annnnoid]

Einstein has been shown to be wrong by the many experiments that show that QM cannot be a hidden variable theory. The topic of this thread is those ""telepathic" methods" so we could say that Einstein was wrong twice .

Well…whether or not the big ‘E’ was wrong…he apparently was not exactly right. Given his achievements (and the complexity of the subject) he can hardly be faulted for the occasional error.

Thing is…this effect is certainly one of the stranger features of QM. Is there something decidedly revolutionary going on here? This experiment (…and, presumably…others before it) seems to confirm some variety of instantaneous communication / information transfer.

Is this an accurate conclusion…or merely an error of measurement / interpretation?

If it is an accurate conclusion…how does this occur?

 

[xtifr]

Just for the record, since he's posting in this thread, and since some of the people here appear to be new, Farsight is a self-described "armchair physicist" with no actual physics credentials (which technically doesn't matter, but should inform the rest of this), who claims the he alone has discovered the "true meaning" of Einstein's work. He has a self-published book called Relativity+: The Theory of Everything which has generated approximately no interest in the broader physics community. (But does have its own thread here on JREF.)

He is convinced that modern physics has completely gone off the rails since Einstein died, and routinely refers to such luminaries as John Wheeler, standard textbooks such as Gravitation, and people who study or teach such books as "cranks". He is convinced that the recent discovery of the Higgs Boson was an experimental error, because no such thing can exist in what he believes Einstein's theories to be.

Opinions on his work and his presentation of Einstein are basically divided between those who find it plausible—a group that as far as I can tell has just one member—and those who think it's utter nonsense—pretty much everyone else. You can decide for yourself. But in general, his ideas are so far out of the mainstream that the mods try to keep his more extreme stuff in the thread on his book. However he's no idiot, and he does know enough stuff that he's tolerated in other threads as long as he doesn't start yelling about all the professional physicists being the "real cranks" too much, or derail things too badly. On a good day, he can offer a useful insight or two.

I have no idea why he chose JREF as the place to hang out and expound his theories, but I suspect it may have something to do with the reception he's received on actual physics-oriented forums. We're a pretty tolerant bunch around here, despite all the teasing we give him.

 

[Reality Check]

Thing is…this effect is certainly one of the stranger features of QM. Is there something decidedly revolutionary going on here? This experiment (…and, presumably…others before it) seems to confirm some variety of instantaneous communication / information transfer.

Quantum teleportation was first observed in 1998 so nothing revolutionary in observing it again after 16 years.
Quantum teleportation of atomic states was done last year over a distance of half a meter: Quantum teleportation between atomic systems over long distances.
Unconditional quantum teleportation between distant solid-state quantum bits is a big advance but not revolutionary. It is the first time that quantum states in a solid have been teleported and the distance of 3 meters is impressive.