A Barandes's Unistochastic Refomulation Applied to Entanglement Swapping

[DrChinese]

The reformulation agrees with all experimental results. You might have reasons to prefer your own interpretation, but failure to agree with experiments is not a valid reason. All interpretations agree with experiment.

I am not asserting an Interpretation. I am pointing out - as I have done in post after post above: The Barandes interpretation makes a specific prediction that is contradicted by experiment. Remote decisions can be detected by Bob without communicating that information from other channels. See #24, where there is an absolute change in what Bob sees. This is experimental fact, and you have yet to dispute this.

You said that per Barandes: "The causal relations that show Alice Charles and Bob do not causally influence one another." So either Barandes does not agree with the predictions of QM, or what he presents is not a proper representation of his Interpretation.

---

And you might want to re-read what you say above. "Failure to agree with experiments is NOT a valid reason" to prefer an interpretation, true enough. But it is instead a good reason to drop that preference. And the statement that "All interpretations agree with experiment" is blatantly wrong. Bell's Theorem would have no significance if that were true. We now know that Local Realistic interpretations are not viable, because they make predictions at odds with experiment. It is generally accepted here that Bell tests (and many other experiments) are by definition* demonstrations of quantum nonlocality.


*By the definition we follow in this subforum, at least.

 

[DrChinese]

I'd be happy to discuss the particulars of the reformulation [edit] as they apply to entanglement swapping [/edit] , which was my motivation for starting this thread.

Well, I used your example; but I don't think you like where it led.

I have said everything I can say on the thread subject, so I will bow out to make sure others can weigh in.

 

[PeterDonis]

I said we need to agree on what the interpretation asserts.

We agree that the interpretation defines "no influence" in a certain way.

That agreement is worth very little, however, since we do not agree on whether adopting that definition of "no influence" is reasonable.

You appear to be trying to get agreement on the latter, not the former. That's not going to happen.

 

[Morbert]

I am not asserting an Interpretation. I am pointing out - as I have done in post after post above: The Barandes interpretation makes a specific prediction that is contradicted by experiment. Remote decisions can be detected by Bob without communicating that information from other channels. See #24, where there is an absolute change in what Bob sees. This is experimental fact, and you have yet to dispute this.

There is an exact correspondence between Barandes's reformulation and quantum theory. Like all established interpretations, it agrees with experiment: It agrees with all correlations in the data produced by Alice Bob and Charles.

 

[PeterDonis]

Remote decisions can be detected by Bob without communicating that information from other channels.

You said Bob needs timestamp information from others to make this detection. That's information from other channels.

Taking your statement in the above quote literally would appear to violate the no signaling theorem. But I don't think you meant it quite that literally.

 

[Fra]

The directed conditional probability distributions are nomological.

Yes, could sop there and we can simply pushed the question into the corner, why these nomological distributions?

If we stop there, did that make anyone any wiser? Ok we got rid of the hilbert stuff, but instead got a mysterious nomological total transition matrix for the whole system that is just there for no particular reason? I think there must be a bigger ambition that simply a reformulation.

What defines the particular form of such constraint for a particular physical system? If this question is not easier to handle in this picture than in he hilbert picture, what have we gained?

My personal opinon is that it IS easier and more intutive.. But this still seems beyond the scope of the correspondence per see, so we can distinguish between the correspondence itself, what it means and the opinions on what god it might do.

/Fredrik

 

[Morbert]

We agree that the interpretation defines "no influence" in a certain way.

That agreement is worth very little, however, since we do not agree on whether adopting that definition of "no influence" is reasonable.

You appear to be trying to get agreement on the latter, not the former. That's not going to happen.

No, I'm looking for agreement that, under reformulation of quantum theory and the account of microphysical causation presented by Barandes, entanglement swapping experiments obey his principle of causal locality. DrChinese believes Barandes's interpretation makes predictions that contradict experiment, which means he does not actually understand Barandes's reformulation. So before any discussion can be had about reasonableness, it must be understood what the reformulation actually entails.

 

[DrChinese]

You said Bob needs timestamp information from others to make this detection. That's information from other channels.

Taking your statement in the above quote literally would appear to violate the no signaling theorem. But I don't think you meant it quite that literally.

The timestamp information itself is only used to indicate a 4-fold event. It does not contain any information about whether a swap occurred or not.

Agreed that there is no FTL signaling, as the timestamp info must be transmitted at light speed via classical channel.

It’s still interesting, because all of the transmitted information can be rolled into a single bit to be sent. The observer transmitting it has no way to know whether a swap even occurred. Just that a qualifying 4-fold event occurred for Bob to analyze.

Of course, suitable BSM/SSM events occur randomly and on the order of a few per second in today’s world. It’s something akin to teleporting an unknown quantum state, except that it has a deterministic character. Since it allows for “decoding” of a remote decision.

 

[martinbn]

It’s something akin to teleporting an unknown quantum state, except that it has a deterministic character. Since it allows for “decoding” of a remote decision.

Swapping is teleportation. Teleportation of a mixed state.

 

[PeterDonis]

I'm looking for agreement that, under reformulation of quantum theory and the account of microphysical causation presented by Barandes, entanglement swapping experiments obey his principle of causal locality.

Isn't this true by definition? I mean "his principle of causal locality" is defined so that entanglement swapping experiments meet it. What's the point of belaboring this?

DrChinese believes Barandes's interpretation makes predictions that contradict experiment

Which is a different question from the one implicit in what I quoted from you at the start of this post. The relevant question here is whether Barandes's interpretation does in fact make all of the same predictions as standard QM. That has nothing whatever to do with whether Barandes's interpretation meets Barandes's own definition of "causal locality" (even leaving aside the fact that, as noted above, belaboring the latter point is pointless).

 

[PeterDonis]

Just that a qualifying 4-fold event occurred for Bob to analyze.

But to confirm that a swap occurred, Bob has to know Alice's measurement result as well as his own. That requires transmitting information from other channels.

 

[Morbert]

Isn't this true by definition? I mean "his principle of causal locality" is defined so that entanglement swapping experiments meet it. What's the point of belaboring this?

@DrChinese Do you agree that entanglement swapping experiments, when analyzed with Barandes's reformulation, satisfies Barandes's principle of causal locality, whether or not you agree with his microphysical theory of causation?

Which is a different question from the one implicit in what I quoted from you at the start of this post. The relevant question here is whether Barandes's interpretation does in fact make all of the same predictions as standard QM. That has nothing whatever to do with whether Barandes's interpretation meets Barandes's own definition of "causal locality" (even leaving aside the fact that, as noted above, belaboring the latter point is pointless).

Both questions are absolutely relevant.

 

[DrChinese]

But to confirm that a swap occurred, Bob has to know Alice's measurement result as well as his own. That requires transmitting information from other channels.

In my particular example (post #2), Alice always has a |0> result. But yes, more generally that would be true as you say. One way or another, Bob must find out Alice's result.

Alternatively, Alice could simply be co-located with Bob without a loss of functionality. Then he would know her result.

 

[DrChinese]

@DrChinese Do you agree that entanglement swapping experiments, when analyzed with Barandes's reformulation, satisfies Barandes's principle of causal locality, whether or not you agree with his microphysical theory of causation?

I agree with @PeterDonis, Barandes' causal locality definition not surprisingly fits with his interpretation. Who would expect otherwise?

I also say it is nothing more than a restatement of an assumption of signal locality. We already knew that nothing Alice does results in any visible changes at Bob's end. If it did, you could perform FTL signaling. That is essentially the same thing as Barandes' causal locality.

 

[Morbert]

I agree with @PeterDonis, Barandes' causal locality definition not surprisingly fits with his interpretation. Who would expect otherwise?

Great! Previously you have presented entanglement swapping as a foil for some interpretations that otherwise readily handle conventional scenarios where two particles are entangled via a past local interaction. I'm glad you agree that, on its own terms, this interpretation frames entanglement swapping as a causally local process, even if you take general issue with this interpretation.

I also say it is nothing more than a restatement of an assumption of signal locality. We already knew that nothing Alice does results in any visible changes at Bob's end. If it did, you could perform FTL signaling. That is essentially the same thing as Barandes' causal locality.

Barandes remarks that the relevant calculations he performs to resolve causality questions are closely related to no-communication theorem. But I will answer this charge in the other thread as it is a more general charge not related to entanglement swapping.

 

[javisot]

There is an exact correspondence between Barandes's reformulation and quantum theory. Like all established interpretations, it agrees with experiment: It agrees with all correlations in the data produced by Alice Bob and Charles.

So, QM(Barandes)=GR?

Or, by definition, is it just as irreconcilable as nonlocal QM like Copenhagen?

QM(Copenhagen)=QM(Barandes)≠GR?

 

[javisot]

I'm glad you agree that, on its own terms, this interpretation frames entanglement swapping as a causally local process, even if you take general issue with this interpretation.

That the swap of (2&3) are considered strictly local processes does not restrict the existence of non-local consequences, (1&4).

 

[PeterDonis]

@DrChinese Do you agree that entanglement swapping experiments, when analyzed with Barandes's reformulation, satisfies Barandes's principle of causal locality, whether or not you agree with his microphysical theory of causation?Both questions are absolutely relevant.

I cannot understand why, because I cannot understand why it's even a question. You're basically asking whether Barandes agrees with himself. Um, what?

 

[PeterDonis]

In my particular example (post #2), Alice always has a |0> result.

Which means that, while Bob technically doesn't require any information from Alice in this special case, it's only because there is no information from Alice to be had anyway. But that's not the kind of case that creates interpretation problems, precisely because Alice's result is fixed. It's the cases where Alice's result is not fixed, any more than Bob's, that raise interpretation challenges.

 

[Fra]

If it is global then it is nonlocal (at least in weak sense).

Yes, in the obvious sense, ANY global constraint, gets is "nonlocal" in the sense that it is common to all spacetime.

Similarly ANY objective constraint is like an objective beable in the sense that it represents observer/context equivalence.

This is exactly the "generic problem" with the nature of law, nature of spacetime and nature of observer equivalence. When thinking about "causation" it seems equally valid to say that initial conditions "cause" the future, as it is to say that the dynamical law, "cause" the future. The distinction between initial conditions and laws from perspective of causation seem ambigous.

And it is why I think trying to reduce "dynamical" into caually local stochastic is progress, but Barandes only takes a small step and we still need to "interpret" the new constraint of time dependent transition matrix; it is beyond the correspondence.

/Fredrik

 

[Morbert]

So, QM(Barandes)=GR?

Or, by definition, is it just as irreconcilable as nonlocal QM like Copenhagen?

QM(Copenhagen)=QM(Barandes)≠GR?

What is GR? General relativity? The correspondence is between unistochastic systems and quantum theory.

That the swap of (2&3) are considered strictly local processes does not restrict the existence of non-local consequences, (1&4).

Under Baradnes's theory of causality, the stochastic processes in entanglement swapping experiments are local throughout. Charles, performing a measurement of any kind on 2 & 3, has no nonlocal influence on 1 & 4.

 

[javisot]

What is GR? General relativity? The correspondence is between unistochastic systems and quantum theory.

Under Baradnes's theory of causality, the stochastic processes in entanglement swapping experiments are local throughout. Charles, performing a measurement of any kind on 2 & 3, has no nonlocal influence on 1 & 4.

QM(Barandes)=QM(Copenhagen)?

 

[Lord Jestocost]

QM(Barandes)=QM(Copenhagen)?

No!
The minimalist ‘Copenhagen’ interpretation doesn't at least assume anything one cannot strictly talk about.

 

[pines-demon]

QM(Barandes)=QM(Copenhagen)?

Mathematically, yes (or at least that's the claim). Interpretationally, very different.

 

[javisot]

No!
The minimalist ‘Copenhagen’ interpretation doesn't at least assume anything one cannot strictly talk about.

Mathematically, yes (or at least that's the claim). Interpretationally, very different.

Barandes claims yes, but I have not been able to verify the veracity of his statements (and by "verify the veracity" I mean checking if all the mathematics of "stochastic-quantum correspondence" is correct). We are talking about different interpretations that must explain the same experimental results.

 

[pines-demon]

@Morbert I am wondering, can you easily recover the usual entanglement result $P(\theta)=\cos^2(\theta/2)$ using Barandes approach?

 

[Morbert]

QM(Barandes)=QM(Copenhagen)?

If you are asking whether Barandes's interpretation is just the Copenhagen interpretation, then no. Instead, Barandes argues a general class of stochastic systems, characterised by a configuration space and a stochastic map, are describable by quantum theories, and hence quantum theories can be interpreted as theories of a general class of stochastic systems.

 

[Morbert]

@Morbert I am wondering, can you easily recover the usual entanglement result $P(\theta)=\cos^2(\theta/2)$ using Barandes approach?

The Bell-inequality-violating correlations would be read from the (undirected) conditional probabilities like $p(a_\theta, t | b_{\theta'}, t)$ where $a_\theta$ and $b_{\theta'}$ are the relevant magnitudes that depend on the system's configuration (Alice, Bob, and their particles, with $\theta$ being Alice's choice of basis and $\theta'$ being Bob's choice of basis). We would arrive at those conditional probabilities with the right stochastic map. So given some initial state $\ket{\Psi}_0 = |\psi\rangle_{12}|\Omega_0\rangle_\mathrm{Alice}|\Omega_0\rangle_\mathrm{Bob}$, we would construct the relevant stochastic map $\Gamma(t)$ where $\Gamma_{\theta\theta',0}(t) = \mathrm{tr}(U^\dagger(t)P_{\theta\theta'} U(t) P_0)$ will reproduce the relevant correlations.

 

[pines-demon]

The Bell-inequality-violating correlations would be read from the (undirected) conditional probabilities like $p(a_\theta, t | b_{\theta'}, t)$ where $a_\theta$ and $b_{\theta'}$ are the relevant magnitudes that depend on the system's configuration (Alice, Bob, and their particles, with $\theta$ being Alice's choice of basis and $\theta'$ being Bob's choice of basis). We would arrive at those conditional probabilities with the right stochastic map. So given some initial state $\ket{\Psi}_0 = |\psi\rangle_{12}|\Omega_0\rangle_\mathrm{Alice}|\Omega_0\rangle_\mathrm{Bob}$, we would construct the relevant stochastic map $\Gamma(t)$ where $\Gamma_{\theta\theta',0}(t) = \mathrm{tr}(U^\dagger(t)P_{\theta\theta'} U(t) P_0)$ will reproduce the relevant correlations.

I kind of get that. But how pragmatic is to derive actual predictions from Barandes’ interpretation compared to the usual way?

 

[Morbert]

I kind of get that. But how pragmatic is to derive actual predictions from Barandes’ interpretation compared to the usual way?

I don't know if there are any uses over and above standard QM yet. Barandes speculates on some possibilities in the timestamp below, but ultimately it is all speculative for now.

[edit] - Fixed timestamp