Exploring Antoine Suarez's Work on Entanglement and Time

In summary, Antoine Suarez's experiment contradicts the idea that information is transmitted through the act of measurement. His experiments seem to suggest that the "before-before" correlation between particles is not caused by any sort of "transmission" of information, but rather by a priori statistical correlations between particles.
  • #1
bankknab
5
0
Hi guys,
I am curious about the work done by Antoine Suarez. I think this is a famous one but I need some more information about this. He concluded :

----------------------------------------------------------------------
The final results

The final results of the experiments with moving measuring devices (see experiments) rule out the possibility to describe the quantum correlations by means of real clocks, in terms of "before" and "after"; nonlocal quantum phenomena cannot be described with the notions of space and time. This means that there is no time ordering behind nonlocal correlations, so the causal order cannot be reduced to the temporal one. Quantum correlations somehow reveal dependence between the events, or logical order. Experiment shows that this dependence, or logical order, is beyond any real time ordering. In the realm of the nonlocal quantum phenomena, things come to pass but the time doesn't seem to pass here.
------------------------------------------------------------------

Is there any critics to this conclusion and his experiment?
Or are we finally concluded that there is no time ordering behind entanglement?
What happened to The interpretation that information is sent backwards in time - is it dead?

Thanks in advance...
 
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  • #2
It helps to give a link to what you're talking about! Your quote apparently comes from the "final results" section at the end of this page:

http://www.quantumphil.org/history.htm

And he links to various papers on his experiments here:

http://www.quantumphil.org/publications.htm#experiments
 
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  • #3
JesseM said:
It helps to give a link to what you're talking about! Your quote apparently comes from the "final results" section at the end of this page:

http://www.quantumphil.org/history.htm

And he links to various papers on his experiments here:

http://www.quantumphil.org/publications.htm#experiments


My apologies...You are right! Thanks for providing thoe links:)
 
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  • #4
anyone? sorry, I am little bit impatient person in nature:)
 
  • #5
Cause and effect seems to be fundamental AFIK and can be viewed to account for special relativity properties of space. That needs time ordering, I would suggest - at least in 3 space.

Entanglement implies an instant time connection between the particles involved. The connection can be instant in 3 space, because it does not break cause and effect, implying no apparent distance in the configuration space, or at least, no recognition of distance. Contradiction? Well, like function(1) = function(2) does not need time to be true when time is not specified.
 
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  • #6
debra said:
Cause and effect seems to be fundamental AFIK and can be viewed to account for special relativity properties of space. That needs time ordering, I would suggest - at least in 3 space.

Entanglement implies an instant time connection between the particles involved. The connection can be instant in 3 space, because it does not break cause and effect, implying no apparent distance in the configuration space, or at least, no recognition of distance. Contradiction? Well, like function(1) = function(2) does not need time to be true when time is not specified.

No!
Entanglement is a priori statistical correlation and not a causal connection be it instantaneous or not. We just see that quantum systems can correlate more strongly than classical. This research is supporting that interpretation.

The mistake one makes is in believing the wave-function is something "out there" instead of a representation of our knowledge of a quantum system. This leads to thinking that because we update the wave function of one half of an entangled pair when we measure the other that some mysterious effect is being transmitted.

As with "collapse" the "effect" is that we have new info about the system and so we update our representation. Hence the logical ordering described.
 
  • #7
jambaugh said:
No!
Entanglement is a priori statistical correlation and not a causal connection be it instantaneous or not. We just see that quantum systems can correlate more strongly than classical. This research is supporting that interpretation.

The mistake one makes is in believing the wave-function is something "out there" instead of a representation of our knowledge of a quantum system. This leads to thinking that because we update the wave function of one half of an entangled pair when we measure the other that some mysterious effect is being transmitted.

Entangled particles remain synchronised in their entangled states when separated in locality, which does not imply cause and effect or transmission of information - I am the last one to try to claim that. Look at the entangled particle wave equation.
 
  • #8
I agree with debra's and jambaugh's comments.

From the papers and website I looked at, Suarez seems to be trying to interpret the results of the "before-before experiment" as supporting the idea of an omnipotent and omniscient being. Some sort of "immaterial" force for "free will" outside of space and time.
 
  • #9
Thanks for your response guys...
If info is not being exchanged between entangled particles, I am curious how this transportation thing works? As far as I know they even made molecular transportation possible. I have always thought transportation is only possible if info is exchanged between entangled particles, no?
 
  • #10
bankknab said:
Thanks for your response guys...
If info is not being exchanged between entangled particles, I am curious how this transportation thing works? As far as I know they even made molecular transportation possible. I have always thought transportation is only possible if info is exchanged between entangled particles, no?
What "transportation thing"?
 
  • #11
I meant teleportation...God!:) my mistake...
 
  • #12
Pardon me debra,
I didn't read carefully enough seeing the "instant time connection" as an assumption of instantaneous causal connection. My bad.
 
  • #13
Suarez has an agenda that you might characterize as religious, but it's nothing secret, and while it bothered me at first I've adjusted to it. He certainly pushes "free will" (cf. his debate with 't Hooft) and describes it as a quantum influence outside of space and time. But he's a good physicist and has worked with the best (Gisin, Zeilinger) so, whatever keeps him motivated.

If you think of an entangled system as entirely physical, from the standpoint of the "separate" particles there really is no separation between them, no matter how great the distances measured. Anton Zeilinger says entanglement appears to conduct its business "outside space and time" although he's being practical, not so much mystical. From a classical perspective the before-before experiment raises issues but then in QM what doesn't?
 
  • #14
nikman said:
If you think of an entangled system as entirely physical, from the standpoint of the "separate" particles there really is no separation between them, no matter how great the distances measured. Anton Zeilinger says entanglement appears to conduct its business "outside space and time" although he's being practical, not so much mystical. From a classical perspective the before-before experiment raises issues but then in QM what doesn't?

I agree with Zeilinger. And there does not seem to be a shared space that all wave functions/ particles can address from all real-space coordinates (ie all localities) in physics at present. It would solve a lot of issues, especially our problem in this thread with entanglement.
 
  • #15
jambaugh said:
The mistake one makes is in believing the wave-function is something "out there" instead of a representation of our knowledge of a quantum system.

Oh, no... That mysterious "knowledge" again...
Dont try to bring the rotting corpse of the Copenhagen interpretation here :)
 
  • #16
Oh. You mean this kind of thing:

"It is wrong to think that the task of physics is to find out how Nature is. Physics concerns what we can say about Nature."

"It from Bit."

"When investigating various interpretations of quantum mechanics one notices that each interpretation contains an element which escapes a complete and full description. This element is always associated with the stochasticity of the individual event in the quantum measurement process. It appears that the implications of this limit to any description of the world has not been sufficiently appreciated with notable exceptions of, for example, Heisenberg, Pauli and Wheeler. If we assume that a deeper foundation of quantum mechanics is possible, the question arises which features such a philosophical foundation might have. It is suggested that the objective randomness of the individual quantum event is a necessity of a description of the world in view of the significant influence the observer in quantum mechanics has. It is also suggested that the austerity of the Copenhagen interpretation should serve as a guiding principle in a search for deeper understanding."

"An elementary quantum system contains one bit of information."

:-|
 
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  • #17
nikman said:
It is also suggested that the austerity of the Copenhagen interpretation should serve as a guiding principle in a search for deeper understanding."

I would agree with the Zeilinger quote above. If I was modelling a quantum behaved particle in a computer I would use the CI equations to do it and some space time parameters. It would behave as the real particle does and give accurate results that agree with experiment.
 
  • #18
debra said:
I would agree with the Zeilinger quote above. If I was modelling a quantum behaved particle in a computer I would use the CI equations to do it and some space time parameters. It would behave as the real particle does and give accurate results that agree with experiment.

Could you show me these specific 'CI equations' which are not part of QM, please?
Hint: CI, MW and TI are in agreement with the experiment. That is why they are called different 'interpretations' of a theory, not different theories.
 
  • #19
The "rotting corpse" you refer to is still the standard framework that almost all progress within the field has been composed in. Why do you have such vitriol for it, despite its excellent predictive power and economy on metaphysical suppositions? QM has introduced a wide range of counter-intuitive concepts that do not behave according to classical mechanical principles, why should the nature of the wavefunction obey something similar to classical wave mechanics? I understand the desire to return to a deterministic worldview, however, the physics strongly suggest that nature is probalistic. All other interpretations just scramble to find ways to manufacture Copenhagen's predictive power and empirical success, but add nothing but metaphysical layers of complexity. The Copenhagen Interpretation is still the dominant pardigm in physics, and has been a standard that alternative interpretations try to meet. It is certainly not a corpse, particularly with the conceptual clarifications of consistent histories.
 
  • #20
Dmitry67 said:
Could you show me these specific 'CI equations' which are not part of QM, please?
Hint: CI, MW and TI are in agreement with the experiment. That is why they are called different 'interpretations' of a theory, not different theories.

Oh I see, you are angry and sarcastic because you are not a CI supporter.

MWI? I am not sure even David Deutsch follows that any more.

Bohm and his pilot waves? Does not conform to SR among other problems with it.

Super Determinism - cannot argue with that (except with a little logic).

CI is just the minimum mathematics that works and probably the best we have got at present - a stepping stone at least - a physical interpretation of some aspects of it should follow.

If you can argue differently, go ahead, no obfuscation though...
 
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  • #21
"Predictive power" is not related to any specific interpretation. SO this:

"All other interpretations just scramble to find ways to manufacture Copenhagen's predictive power and empirical success," - is FALSE: it was a success of QM, not CI !

"however, the physics strongly suggest that nature is probalistic" - in MW it is not.

"Copenhagen Interpretation is still the dominant pardigm in physics" - search this forum and check the results of the poll in 2006 I guess - I did it. You will be surprised by the results.

We had already discussed Interpretations in a different thread, but I just hate that when people ask something here they are not given a choice to chose the interpretation they like, they are even not informed about these interpretations, instead, they are given a part of CI vision like it is an absolute truth.
 
  • #22
P.S.
I don't want to highjack this thread into a holy war 'what interpretation is better'
But could we instead of something like this

jambaugh said:
The mistake one makes is in believing the wave-function is something "out there" instead of a representation of our knowledge of a quantum system.

Add something like

For example, in CI the wave-function is something "out there" instead of a representation of our knowledge of a quantum system (Note: there are other interpretations)

Are you for the democracy of the intepretations or for the dictatorship of the one? :)
 
  • #23
The "austerity" quote re: CI is, once again, Anton Zeilinger. I'm kind of an apostle for his and Časlav Brukner's "informational interpretation" of QM, which is largely an extension of Bohr and Heisenberg combined with Wheeler's "It from Bit." The approach is a drill-down into the world where you keep digging until you hit the simplest binary propostion: that physical system carrying the answer to only one "yes or no" proposition (or, more than one classically probabilistic measurement with the probabilities adding up to One), beyond which you encounter gibberish (i.e., incompressible quantum randomness).

That system is any individual particle-wave. A favored single-bit property for definite measurement is the system's spin along a given axis. Or, if you're doing quantum computation, the system is thought of as a qubit; you measure the qubit and it collapses into a single "0" or "1" classical bit. That's all the information you're going to extract from the thing. It's meaningless to think of knowledge or information or even reality beyond this. Love it or hate it you can't beat that for interpretive austerity.
 
  • #24
nikman said:
The "austerity" quote re: CI is, once again, Anton Zeilinger. I'm kind of an apostle for his and Časlav Brukner's "informational interpretation" of QM, which is largely an extension of Bohr and Heisenberg combined with Wheeler's "It from Bit." The approach is a drill-down into the world where you keep digging until you hit the simplest binary propostion: that physical system carrying the answer to only one "yes or no" proposition (or, more than one classically probabilistic measurement with the probabilities adding up to One), beyond which you encounter gibberish (i.e., incompressible quantum randomness).

That system is any individual particle-wave. A favored single-bit property for definite measurement is the system's spin along a given axis. Or, if you're doing quantum computation, the system is thought of as a qubit; you measure the qubit and it collapses into a single "0" or "1" classical bit. That's all the information you're going to extract from the thing. It's meaningless to think of knowledge or information or even reality beyond this. Love it or hate it you can't beat that for interpretive austerity.

Well, it was John Wheeler who joked once that we are all living in a giant computer. I read Časlav Brukner's work with interest but was left a little confused which sometimes means I did not fully understand it, but it can mean that the author is also a little confused. ...Something about spin containing entanglement data was not fully clear to me.
 
  • #25
debra said:
Well, it was John Wheeler who joked once that we are all living in a giant computer. I read Časlav Brukner's work with interest but was left a little confused which sometimes means I did not fully understand it, but it can mean that the author is also a little confused. ...Something about spin containing entanglement data was not fully clear to me.

That last sounds like the paper where they quantify entanglement using spin correlations from a previous neutron-scattering experiment. That's not informatics per se.

Wheeler was probably reflecting his late-life association with Max Tegmark and the "Decoherence Gang" (which includes Dieter Zeh, Erich Joos as well as Tegmark and others). Those people have a lot in common with David Deutsch, particularly commitment to many-worlds/multiple universes. The Universe tends to become a Computer and you need more than one universe simply to store all the data in. Zielinger and Brukner specifically eschew that approach.

There are several Informational Interpretation papers from Zeilinger. I'll suggest two:

1. The very first, from 1999. Lucidly lays out the basics:

http://www.quantum.univie.ac.at/zeilinger/foundations.pdf

2. Zeilinger and Brukner develop the approach in much more technical detail. "Information Space" is introduced. Their controversial reformulation of Shannon's information-content theorem is noted. And other stuff:

http://arxiv.org/pdf/quant-ph/0212084v1

They're both clearly-presented. So if you want to either agree or disagree you don't need to struggle to figure out what they're talking about.
 
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  • #26
nikman said:
That last sounds like the paper where they quantify entanglement using spin correlations from a previous neutron-scattering experiment. That's not informatics per se.

Wheeler was probably reflecting his late-life association with Max Tegmark and the "Decoherence Gang" (which includes Dieter Zeh, Erich Joos as well as Tegmark and others). Those people have a lot in common with David Deutsch, particularly commitment to many-worlds/multiple universes. The Universe tends to become a Computer and you need more than one universe simply to store all the data in. Zielinger and Brukner specifically eschew that approach.

There are several Informational Interpretation papers from Zeilinger. I'll suggest two:

1. The very first, from 1999. Lucidly lays out the basics:

http://www.quantum.univie.ac.at/zeilinger/foundations.pdf

2. Zeilinger and Brukner develop the approach in much more technical detail. "Information Space" is introduced. Their controversial reformulation of Shannon's information-content theorem is noted. And other stuff:

http://arxiv.org/pdf/quant-ph/0212084v1

They're both clearly-presented. So if you want to either agree or disagree you don't need to struggle to figure out what they're talking about.

Thanks for those references, they are wonderful. I shall probably try to start other threads to discuss the issues raised. Seems to me the correct path to go and fits with what I think anyway - very exciting.

Re entanglement 2 spin bits solution: providing 4 possible outcomes (2 * spin same way + 2 * opposite spins=4 altogether) it then says that those 2 bits are used for the combined (entangled) two particles description and there are no more bits left to describe the individual particles states - I am trying to discover how this removes the need for exchange of correlation between widely separated particles. Maybe it does but, I cannot quite see how - so I will re-read it later as I most probably am missing the point. If it does then it would explain entanglement very well IMO.
 
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  • #27
debra said:
Re entanglement 2 spin bits solution: providing 4 possible outcomes (2 * spin same way + 2 * opposite spins=4 altogether) it then says that those 2 bits are used for the combined (entangled) two particles description and there are no more bits left to describe the individual particles states - I am trying to discover how this removes the need for exchange of correlation between widely separated particles. Maybe it does but, I cannot quite see how - so I will re-read it later as I most probably am missing the point. If it does then it would explain entanglement very well IMO.

Re: VIII. ENTANGLEMENT - MORE INFORMATION IN JOINT PROPERTIES THAN IN INDIVIDUALS ...

The information is "distributed" between the entangled particles. Sadly I can't supply a literal explanation, just an analogy based on the Zeilinger group's (successful) teleportation experiments going back several years. Snapshot:

http://tinyurl.com/6fk4yk

Okay, XOR is a computer logic gate whose logic is: "two same inputs equal (that is: they output) zero, and two different inputs equal (or output) one". Say you want to transmit the binary expression of the decimal number 116, but transmit it securely encrypted and in two separate messages to make interception more difficult. In binary "116" is "01110100". You need to split that number into two separate transmissions (for purposes of this admittedly shlock analogy think "distribute it between two particles"). You work toward that goal by tossing a coin (without referring at all to the actual number itself) for each digit of the first "distributed message" or sub-message (say, heads means zero, tails means one). You toss your coin and get 1 for the first digit, 0 for the second and so on until you accumulate eight random digits. Then you construct a plug, which will be just as random, to get you, via XOR logic, to the actual number:

(1.) 10101001 (tossed coin ... first message)
(2.) 11011101 (plug ... second message)
(3.) 01110100 (composite message: the actual number)

Now, if someone intercepts (1.) or (2.) without the other sub-message they've got nothing. If they manage to intercept both (1.) and (2.) but without knowing they're XOR-encrypted they have nothing either. In terms of the actual message all they have is random junk. But with both of the sub-messages and knowledge of the XOR encryption they've got it all.

That's sort of an analogue to "having more information in joint properties" (the composite final message) "than in individual properties" (the separate sub-messages).
 
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  • #28
"I am trying to discover how this removes the need for exchange of correlation between widely separated particles."

Which is your basic concern and which I failed to respond to. Zeilinger would, I think, say it doesn't. How entanglement works is still a mystery. "Information" may be the stuff operating "outside of space and time" that connects the particles (if we must insist on thinking of them as physically separated simply because they're billions of miles distant from each other).

I sense that Brukner and Zeilinger see this question as indicating the next realm of discovery in physics: they want to find out what exactly "outside of space and time" means, what can be learned about it, if anything. Re-casting QM as "a science of information" is apparently key.
 
  • #29
nikman said:
I sense that Brukner and Zeilinger see this question as indicating the next realm of discovery in physics: they want to find out what exactly "outside of space and time" means, what can be learned about it, if anything. Re-casting QM as "a science of information" is apparently key.

Yes, I agree, its not easy to mix information theories and QM IMO. I have done both and believe we are missing key ideas still. I have done a lot of programming and can easily imagine physics particles as objects with properties and behaviors, but we are missing how its being driven from outside space-time. I note that it would not be easy to analyse screen pixel behaviors ( in a 3D virtual reality) using Hilbert Space and differential mathematics and come up with a theory of how a computer program implements itself.

What work is being done in the field of information theories as a description of quantum phenomena? How can it be proved?
 
  • #30
debra said:
Yes, I agree, its not easy to mix information theories and QM IMO. I have done both and believe we are missing key ideas still. I have done a lot of programming and can easily imagine physics particles as objects with properties and behaviors, but we are missing how its being driven from outside space-time. I note that it would not be easy to analyse screen pixel behaviors ( in a 3D virtual reality) using Hilbert Space and differential mathematics and come up with a theory of how a computer program implements itself.

What work is being done in the field of information theories as a description of quantum phenomena? How can it be proved?

Let me just toss out this mishmash of material because I happen to be aware of it. The last stuff (Brukner and Kofler) is from Zeilinger's group obviously. Diederik Aerts is a very interesting guy, knew John Bell well when he (Aerts) was a young post-doc at Geneva, and conducted workshops with Alain Aspect at the time Aspect was setting up his first experiment.

.....

John C. Baez and Mike Stay:

Physics, Topology, Logic and Computation:
A Rosetta Stone


Category theory is a very general formalism, but there is a certain special way that physicists use categories which turns out to have close analogues in topology, logic and computation. A category has objects and morphisms, which represent things and ways to go between things. In physics, the objects are often physical systems, and the morphisms are processes turning a state of one physical system into a state of another system -- perhaps the same one. In quantum physics we often formalize this by taking Hilbert spaces as objects, and linear operators as morphisms.

http://math.ucr.edu/home/baez/rosetta.pdf

.....


Diederik Aerts and Marek Czachor:

Cartoon Computation: Quantum-like computing without
quantum mechanics


We present a computational framework based on geometric structures. No quantum mechanics is involved, and yet the algorithms perform tasks analogous to quantum computation. Tensor products and entangled states are not needed — they are replaced by sets of basic shapes. To test the formalism we solve in geometric terms the Deutsch-Jozsa problem, historically the first example that demonstrated the potential power of quantum computation. Each step of the algorithm has a clear geometric interpetation and allows for a cartoon representation.

http://tinyurl.com/bjvsds

slightly different version:

http://arxiv.org/pdf/quant-ph/0611279v2

and:

Quantum Aspects of Semantic Analysis and Symbolic Artificial Intelligence

Modern approaches to semanic analysis if reformulated as Hilbert-space problems reveal formal structures known from quantum mechanics. Similar situation is found in distributed representations of cognitive structures developed for the purposes of neural networks. We take a closer look at similarites and differences between the above two fields and quantum information theory.

http://arxiv.org/pdf/quant-ph/0309022v4


.....


Časlav Brukner & Johannes Kofler

Classical world arising out of quantum physics under the restriction of coarse-grained measurements

Conceptually different from the decoherence program, we present a novel theoretical approach to macroscopic realism and classical physics within quantum theory. It focuses on the limits of observability of quantum effects of macroscopic objects, i.e., on the required precision of our measurement apparatuses such that quantum phenomena can still be observed. First, we demonstrate that for unrestricted measurement accuracy no classical description is possible for arbitrarily large systems. Then we show for a certain time evolution that under coarse-grained measurements not only macrorealism but even the classical Newtonian laws emerge out of the Schrödinger equation and the projection postulate.

http://arxiv.org/pdf/quant-ph/0609079v3

Essentially the same material but adapted from a PowerPoint presentation. Pretty cool:

http://www.fjfi.cvut.cz/workshop/Workshop_Prague_2008/presentations/Brukner_measurements.pdf
 
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  • #31
nikman said:
Let me just toss out this mishmash of material because I happen to be aware of it. The last stuff (Brukner and Kofler) is from Zeilinger's group obviously. Diederik Aerts is a very interesting guy, knew John Bell well when he (Aerts) was a young post-doc at Geneva, and conducted workshops with Alain Aspect at the time Aspect was setting up his first experiment.

.....

John C. Baez and Mike Stay:

Physics, Topology, Logic and Computation:
A Rosetta Stone


Category theory is a very general formalism, but there is a certain special way that physicists use categories which turns out to have close analogues in topology, logic and computation. A category has objects and morphisms, which represent things and ways to go between things. In physics, the objects are often physical systems, and the morphisms are processes turning a state of one physical system into a state of another system -- perhaps the same one. In quantum physics we often formalize this by taking Hilbert spaces as objects, and linear operators as morphisms.

http://math.ucr.edu/home/baez/rosetta.pdf

.....


Diederik Aerts and Marek Czachor:

Cartoon Computation: Quantum-like computing without
quantum mechanics


We present a computational framework based on geometric structures. No quantum mechanics is involved, and yet the algorithms perform tasks analogous to quantum computation. Tensor products and entangled states are not needed — they are replaced by sets of basic shapes. To test the formalism we solve in geometric terms the Deutsch-Jozsa problem, historically the first example that demonstrated the potential power of quantum computation. Each step of the algorithm has a clear geometric interpetation and allows for a cartoon representation.

http://tinyurl.com/bjvsds

slightly different version:

http://arxiv.org/pdf/quant-ph/0611279v2

and:

Quantum Aspects of Semantic Analysis and Symbolic Artificial Intelligence

Modern approaches to semanic analysis if reformulated as Hilbert-space problems reveal formal structures known from quantum mechanics. Similar situation is found in distributed representations of cognitive structures developed for the purposes of neural networks. We take a closer look at similarites and differences between the above two fields and quantum information theory.

http://arxiv.org/pdf/quant-ph/0309022v4


.....


Časlav Brukner & Johannes Kofler

Classical world arising out of quantum physics under the restriction of coarse-grained measurements

Conceptually different from the decoherence program, we present a novel theoretical approach to macroscopic realism and classical physics within quantum theory. It focuses on the limits of observability of quantum effects of macroscopic objects, i.e., on the required precision of our measurement apparatuses such that quantum phenomena can still be observed. First, we demonstrate that for unrestricted measurement accuracy no classical description is possible for arbitrarily large systems. Then we show for a certain time evolution that under coarse-grained measurements not only macrorealism but even the classical Newtonian laws emerge out of the Schrödinger equation and the projection postulate.

http://arxiv.org/pdf/quant-ph/0609079v3

Essentially the same material but adapted from a PowerPoint presentation. Pretty cool:

http://www.fjfi.cvut.cz/workshop/Workshop_Prague_2008/presentations/Brukner_measurements.pdf

Thanks for these references. They showed me (in a shocking way) what little is known about interpreting quantum physics in terms of information.
 
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  • #32
bankknab said:
Hi guys,
I am curious about the work done by Antoine Suarez. I think this is a famous one but I need some more information about this. He concluded :

----------------------------------------------------------------------
The final results

The final results of the experiments with moving measuring devices (see experiments) rule out the possibility to describe the quantum correlations by means of real clocks, in terms of "before" and "after"; nonlocal quantum phenomena cannot be described with the notions of space and time. This means that there is no time ordering behind nonlocal correlations, so the causal order cannot be reduced to the temporal one. Quantum correlations somehow reveal dependence between the events, or logical order. Experiment shows that this dependence, or logical order, is beyond any real time ordering. In the realm of the nonlocal quantum phenomena, things come to pass but the time doesn't seem to pass here.
------------------------------------------------------------------

Is there any critics to this conclusion and his experiment?
Or are we finally concluded that there is no time ordering behind entanglement?
What happened to The interpretation that information is sent backwards in time - is it dead?

Thanks in advance...

It is provable false, because one can use pilot wave theory as a counterexample. This interpretation of QT gives the same predictions as QT but has a well-defined causal ordering in time.
 
  • #33
Ilja said:
It is provable false, because one can use pilot wave theory as a counterexample. This interpretation of QT gives the same predictions as QT but has a well-defined causal ordering in time.

A recent experiment by Nicolas Gisin's group (with which Suarez is informally affiliated) claims that for the Bohmian model to work there'd need to be a superluminal influence operating at a magnitude four times greater than lightspeed.

http://arxiv.org/pdf/0808.3316
 
  • #34
nikman said:
A recent experiment by Nicolas Gisin's group (with which Suarez is informally affiliated) claims that for the Bohmian model to work there'd need to be a superluminal influence operating at a magnitude four times greater than lightspeed.

http://arxiv.org/pdf/0808.3316

I didn't follow what they were saying about that. A Bohmian theory is going to be non-local anyway, So how does providing a lower bound on the "speed of quantum information" (their term) being greater than 10^4c rule out a Bohmian theory?

It's a great experiment by the way, very clever use of fiber optics and the movement of the Earth through space.
 
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  • #35
DrChinese said:
I didn't follow what they were saying about that. A Bohmian theory is going to be non-local anyway, So how does providing a lower bound on the "speed of quantum information" (their term) being greater than 4c rule out a Bohmian theory?

It's a great experiment by the way, very clever use of fiber optics and the movement of the Earth through space.

It doesn't rule it out imo. They piled serious doubt upon, not disproved. You have to admit a lower bound of 10,000 times light speed for pilot-waves is a big swallow. When you consider those results along with the before-before experimental tests (which Suarez sees as ruling out the Bohm variety of nonlocal realism) it makes Bohmian mechanics seem rather less plausible even than before.

What I wish I understood is why Bohm's is a realistic model not ruled out by Leggett-Garg.

BTW the Zeilinger group challenged the experiment's conceptualization:

http://arxiv.org/abs/0810.4452

and was replied to:

http://arxiv.org/abs/0810.4607
 
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