Loophole-free demonstration of nonlocality?

bohm2

Is anyone familiar with Suarez's papers in this area? I've posted his most recent and pertinent papers on the topic below and even though I read them all, I'm still having trouble understanding his arguments:

Further considerations on the similarities and differences between the kind of nonlocality demonstrated by our experiment and the better known form of nonlocality revealed by the violation of Bells inequality will be presented by some of us in a forthcoming publication.

Single-photon space-like antibunching
http://lanl.arxiv.org/pdf/1204.1712.pdf

The "forthcoming publications" include the following:

I discuss an experiment demonstrating nonlocality and conservation of energy under the assumption that the decision of the outcome happens at detection. The experiment does not require Bell's inequalities and is loophole-free...If one assumes that the decision of the outcome happens at detection, the experiment presented above is a clear demonstration of nonlocality (likely the first loophole-free one), and shows that this principle rules the whole quantum physics...If one rejects the view that the outcome is decided at detection, then one has to accept de Broglie's "empty wave" and at the end "many worlds", where the experimental violation of Bell's inequality even without detection loophole does not prove nonlocality.

"Empty waves", "many worlds", "parallel lives" and nonlocal decision at detection
http://lanl.arxiv.org/pdf/1204.1732.pdf

Interestingly, the PBR theorem is also mentioned in his most recent paper:

This interpretation is proved to be at odds with quantum mechanics by the recently established PBR theorem [11]. The formulation of this theorem according to [10, 12] shows that it rules out models that are "less random than quantum" but not models "less nonlocal than quantum". Conversely, the falsification of models "less nonlocal than quantum" [9] does not falsify "models less random than quantum".

Decision at the beam-splitter, or decision at detection, that is the question
http://lanl.arxiv.org/pdf/1204.5848.pdf

DrChinese

Very interesting stuff. Shows how these theorems - Bell, PBR, and now Suarez' - are allowing us to home in on things.

As I see the conclusion of these, the MWI picture is being attacked (although I may have misunderstood that point). He is asserting non-locality, although as I see it the time symmetric interpretations are not affected. Some people call these non-local although I don't usually group them that way. I call the results consistent with quantum non-locality, and the results are certainly what I would have expected. In fact...

I was surprised to see how closely the "Single-photon space-like antibunching" experiment was to earlier experiments, here is one example:

http://people.whitman.edu/~beckmk/QM.../Thorn_ajp.pdf
Observing the quantum behavior of light in an undergraduate laboratory (2003)

They already knew that the 25% prediction of a local theory for double detections did not occur, and would be strictly against the quantum picture. This setup used the heralded photon and the beamsplitter as in the newer one, but did not enforce strict spacelike separation. The extension in the newer experiment was the transition from strict timelike to strict spacelike separation, which clarified those differences with the local picture.

San K

Quote by bohm2

Interestingly, the PBR theorem is also mentioned in his most recent paper:
Decision at the beam-splitter, or decision at detection, that is the question
http://lanl.arxiv.org/pdf/1204.5848.pdf

From the article/reference above:

Quote by Suarez

Can quantum mechanics be improved?|Does
the previous conclusions mean that quantum mechanics
is the ultimate theory and will not experience any further
improvement in the future? Not by any means. Quan-
tum physics has still to solve for instance the so called
\measurement problem" (Schrodinger cat paradox).

I thought the Schrodinger cat paradox (like the Twin paradox in relativity) was resolved before/at the time the paradox was created.

Both the paradoxes, I thought, we created to illustrate how they could be resolved within the frame work of QM (for Schrodinger cat paradox) or Relativity (for Twin paradox).

The Schrodinger cat paradox is resolved by the fact that the entanglement (superposition of states) is broken at some point/event after emission from the radioactive decay. We may not know exactly what that point/event is however there is no paradox.

or alternatively we can say they were never paradoxes, (its a matter of semantics) since they were resolved at the time of creation (or little before).

Side note: all the paradoxes of relativity were resolved at the time of creation

StevieTNZ

Quote by San K

From the article/reference above:

I thought the Schrodinger cat paradox (like the Twin paradox in relativity) was resolved before/at the time the paradox was created.

Both the paradoxes, I thought, we created to illustrate how they could be resolved within the frame work of QM (for Schrodinger cat paradox) or Relativity (for Twin paradox).

The Schrodinger cat paradox is resolved by the fact that the entanglement (superposition of states) is broken at some point/event after emission from the radioactive decay. We may not know exactly what that point/event is however there is no paradox.

or alternatively we can say they were never paradoxes, (its a matter of semantics) since they were resolved at the time of creation (or little before).

Side note: all the paradoxes of relativity were resolved at the time of creation

I don't think the cat paradox has been resolved at all.

San K

Quote by StevieTNZ

I don't think the cat paradox has been resolved at all.

I think that Schrodinger himself knew there was no cat paradox and he brought/made this up just to illustrate (or better understand) entanglement and to go further.....for the same reason the twin paradox was bought up to illustrate (or better understand) relativity and to show that relativity still works and the twin paradox is resolvable within the framework of relativity.

Schrodinger was, I think, simply trying to bring out the idea that : it is hard to pin down when the entanglement breaks down.

None of them is a "true" paradox (its a matter of semantics though).

I am not aware of any "true/real/unsolved" paradox in physics/science, however I am not a physicist/scientist, so maybe true/unresolved paradoxes exist that I am not aware of.

martinbn

Quote by San K

I think that Schrodinger himself knew there was no cat paradox and he brought/made this up just to illustrate (or better understand) entanglement and to go further.....

What entanglement in the Schrodinger's cat "paradox"?

San K

Quote by martinbn

What entanglement in the Schrodinger's cat "paradox"?

the entanglement between the atoms that are emitted from the decaying radioactive substance in the chamber with the cat.

Martinbn -- what is your point? what is your hypothesis? the conversation can be faster if you were to disclose that.

martinbn

Quote by San K

the entanglement between the atoms that are emitted from the decaying radioactive substance in the chamber with the cat.

Martinbn -- what is your point? what is your hypothesis? the conversation can be faster if you were to disclose that.

My point is that the point of Schrodinger was not to illustrate (or better understand) entanglement, but to show that extrapolating quantum mechanical conlusions to the macro world leads to absurdity.

DrChinese

Suarez is asking: at what point is the superposition of states decided? Is it done at the point in the apparatus where the beamsplitter appears? Or is it done later, when the final configuation is known and the particle is detected?

A local realistic approach says that it must be decided at the beamsplitter, and that leads to a contradiction with his experiment (because sometimes a single photon should lead to 2 clicks, sometimes 0, but QM always predicts 1).

Where I get a bit confused is how the jump is made to non-locality. He uses a chain of logic to get this, but it seems to me that non-realistic interpretations are not ruled out.

San K

Quote by DrChinese

Suarez is asking: at what point is the superposition of states decided? Is it done at the point in the apparatus where the beamsplitter appears? Or is it done later, when the final configuation is known and the particle is detected?

A local realistic approach says that it must be decided at the beamsplitter, and that leads to a contradiction with his experiment (because sometimes a single photon should lead to 2 clicks, sometimes 0, but QM always predicts 1).

well summarized Dr Chinese

Quote by DrChinese

Where I get a bit confused is how the jump is made to non-locality. He uses a chain of logic to get this, but it seems to me that non-realistic interpretations are not ruled out.

I have not gone over it yet, maybe someone else in the forum might have.

zonde

Quote by DrChinese

Suarez is asking: at what point is the superposition of states decided? Is it done at the point in the apparatus where the beamsplitter appears? Or is it done later, when the final configuation is known and the particle is detected?

A local realistic approach says that it must be decided at the beamsplitter, and that leads to a contradiction with his experiment (because sometimes a single photon should lead to 2 clicks, sometimes 0, but QM always predicts 1).

Where I get a bit confused is how the jump is made to non-locality. He uses a chain of logic to get this, but it seems to me that non-realistic interpretations are not ruled out.

As I understood Suarez is assuming that decision is made at the event of detection. Because there are two spatially separate detectors measurement process is non-local (given results of experiment).
But if you assume decision is made at beamsplitter his reasoning does not apply.

bohm2

Quote by DrChinese

Suarez is asking: at what point is the superposition of states decided? Is it done at the point in the apparatus where the beamsplitter appears? Or is it done later, when the final configuation is known and the particle is detected? A local realistic approach says that it must be decided at the beamsplitter, and that leads to a contradiction with his experiment (because sometimes a single photon should lead to 2 clicks, sometimes 0, but QM always predicts 1). Where I get a bit confused is how the jump is made to non-locality. He uses a chain of logic to get this, but it seems to me that non-realistic interpretations are not ruled out.

I don't think non-realism can ever be brought down? I'm still a bit confused but this sentence by him in a paper that just came out today, does make it a bit clearer and is consistent with what you wrote:

If the decision happens at detection and D(0) and D(1) are space-like separated, then nonlocal coordination is required in order to ensure conservation of the energy in each single quantum event (that is, avoid that sometimes both detectors fire together provoking "one photon, two counts", and sometimes none of them fires, provoking "one photon, no count").

By contrast assuming decision at the beam-splitter BS1 permits to escape nonlocality in single-particle interference experiments (Figure 2), but on the price of assuming de Broglie's "empty waves", that is, entities propagating within space-time that do not carry energy and momentum and are in principle inaccessible to observation. Apparently, a likely subconscious desire to fight nonlocality without giving up the conservation of energy contrived Einstein to move from decision at detection to decision at the beam-splitter. And the move brought about the more complicated EPR argument.

Interestingly, in this quote he appears to suggest that the "pilot wave" inevitably leads to "many worlds" or at least, that Bohmians can't provide good arguments for opposing "many worlds"? He writes:

This interpretation ("many world") denies both Principles A and Q, and therefore is the consequent continuation and fulfillment of the "empty wave" program. It is important to be aware of the fact that if one accepts decision at the beam-splitter and "empty waves" one rejects (without realizing it) the Principles A and Q, and then one will not be able to oppose "many worlds".

Nonlocality at detection and conservation of energy: Was Einstein looking for an "epistemic" interpretation, a "superdeterministic" one, or both?
http://lanl.arxiv.org/pdf/1205.4451.pdf

akhmeteli

Quote by bohm2

Is anyone familiar with Suarez's papers in this area? I've posted his most recent and pertinent papers on the topic below and even though I read them all, I'm still having trouble understanding his arguments:

Single-photon space-like antibunching
http://lanl.arxiv.org/pdf/1204.1712.pdf

The "forthcoming publications" include the following:

"Empty waves", "many worlds", "parallel lives" and nonlocal decision at detection
http://lanl.arxiv.org/pdf/1204.1732.pdf

Interestingly, the PBR theorem is also mentioned in his most recent paper:
Decision at the beam-splitter, or decision at detection, that is the question
http://lanl.arxiv.org/pdf/1204.5848.pdf

Let me note the following:

1) For some mysterious reason, Gisin does not claim anything "loophole-free", Suarez does.
2) It looks like Suarez' articles that you quote are unpublished.

Furthermore, I don't believe there is any "loophole-free" evidence of nonlocality in Suarez' articles or in the experiment by Gisin e.a. Indeed, even according to Suarez, there is evidence of nonlocality only if we assume "collapse at detectors":

"As it is well known, according to standard quantum mechanics which detector clicks (the outcome) becomes determined at the detection. In fact, most physicists share this view also referred to as "the collapse of the wavefunction at detection" by the Copenhagen (standard) interpretation. "Outcome's decision at detection" shall be the basic assumption in this paper." (http://lanl.arxiv.org/pdf/1204.1732.pdf )

I believe this is a loophole in Suarez' reasoning. Let me remind you that
1) “no positive experimental evidence exists for physical state-vector collapse” (M. Schlosshauer, Annals of Physics, 321 (2006) 112-149))
2) collapse and unitary evolution (dynamics) of quantum mechanics are mutually contradictory (see, e.g., http://plato.stanford.edu/entries/qt-measurement/ and references there)

bohm2

Quote by akhmeteli

Let me note the following:

1) For some mysterious reason, Gisin does not claim anything "loophole-free", Suarez does.
2) It looks like Suarez' articles that you quote are unpublished.

I'm still lost why he claims "loophole-free" but the first paper which seems to serve the basis for his arguments is published in Physics Letters A (May 11/12):

Single-photon space-like antibunching
http://www.sciencedirect.com/science...75960112005646

akhmeteli

Quote by bohm2

I'm still lost why he claims "loophole-free" but the first paper which seems to serve the basis for his arguments is published in Physics Letters A (May 11/12):

Single-photon space-like antibunching
http://www.sciencedirect.com/science...75960112005646

Yes, but there are no "loophole-free" claims in the published article (I should have said that the preprints signed by Suarez alone are apparently unpublished). As I said, for some reason, Gisin avoids such claims :-) Their joint paper may be the basis for Suarez' arguments, but not for his collapse assumption.

San K

Does the below paper demonstrate non-locality in a loophole-free manner?

http://physics.nist.gov/Divisions/Di...terference.pdf

akhmeteli

Quote by San K

Does the below paper demonstrate non-locality in a loophole-free manner?

http://physics.nist.gov/Divisions/Di...terference.pdf

As far as I know, experts agree that there has been no loophole-free demonstration of nonlocality so far. Do the authors of the article you quote claim such demonstration?

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San K	Does the below paper demonstrate non-locality in a loophole-free manner? http://physics.nist.gov/Divisions/Di...terference.pdf