Pseudorandomness of correlation

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Discussion Overview

The discussion revolves around the nature of correlations observed in the detection of polarization-entangled photons, particularly focusing on the implications of these correlations for the concepts of randomness and pseudorandomness. Participants explore the relationship between the orientation of polarization filters and the resulting detection outcomes, considering whether these correlations suggest a deterministic influence or if they can be classified as truly random.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants propose that the correlation between the orientations of the filters and the detection outcomes suggests that the detections may not be completely random, but rather pseudorandom, as they appear to be influenced by the filter settings.
  • Others argue that pseudorandomness implies a causal relationship for outcomes, referencing concepts from quantum mechanics such as EPR and Bell's theorem, which challenge the notion of hidden variables.
  • One participant suggests that the wavefunction of the entangled pair could be viewed as a 'cause' for the observed correlation, though this perspective is seen by some as potentially oversimplifying the matter.
  • Another participant emphasizes that the correlation is clearly implied by the wavefunction, asserting that preparing a system in a specific state leads to predictable outcomes, while acknowledging that this interpretation may not satisfy all perspectives.
  • There is a discussion about whether the joint wavefunction, particularly in the singlet state, defines or merely implies the correlation, indicating a need for further clarification on this point.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between randomness and correlation in quantum mechanics, with no consensus reached on whether the correlations imply pseudorandomness or if they can be fully explained by the wavefunction. The discussion remains unresolved with multiple competing interpretations presented.

Contextual Notes

Participants acknowledge the complexity of the concepts involved, including the influence of filter orientation on detection outcomes and the implications of quantum mechanics on the nature of randomness. There are indications of missing assumptions and the need for further exploration of definitions related to randomness and causality.

entropy1
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Suppose we have a source of polarization-entangled photons, that fires pairs of photons in opposite directions at two detectors with orientation-adjustable polarizationfilters in front of them. Obviously, there is a correlation between the orientation of the respective filters and the joint detection correlation. Equally obvious is that the measured correlation is cos2(β-α), with α and β the angles of the respective filters.

So, in my eyes this seems to suggest that the distribution of the detection of the photons at either side gets at least partly influenced, or even determined, by the orientation of the filters or the quantitative value of the correlation (cos2(β-α)). Mind you, the distribution of the detections! This can happen at the one side, the other side, or both sides, we don't know.

Does the fact that the distribution of the detections gets consequently and lawfully 'affected' not suggest that the detections are not completely random, but rather pseudorandom? That is, to consistently constitute a certain correlation between the detections at both sides, we have to have more than 'pure' random distributions at each end?

NOTE: It seems to me a relation between space (orientation of the filters) and time (the moment of detection yes/no), in relation to quantization (that we get a correlation in the first place).
 
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entropy1 said:
Does the fact that the distribution of the detections gets consequently and lawfully 'affected' not suggest that the detections are not completely random, but rather pseudorandom? That is, to consistently constitute a certain correlation between the detections at both sides, we have to have more than 'pure' random distributions at each end?

NOTE: It seems to me a relation between space (orientation of the filters) and time (the moment of detection yes/no), in relation to quantization (that we get a correlation in the first place).

I don't see how your idea relates to the difference between pseudo-randomness and true randomness. I associate pseudo-randomness (in this context) with there existing a cause of an outcome.

There are reasons to suggest there is a "cause" to outcomes (see EPR). But there are also reasons to reject those (see Bell).
 
DrChinese said:
I don't see how your idea relates to the difference between pseudo-randomness and true randomness. I associate pseudo-randomness (in this context) with there existing a cause of an outcome.
I would say the orientation of the filters has an influence on the distribution. If you could call that a 'cause', I don't know...

On the other hand, maybe more should be taken into account and I am oversimplying this matter, which would be plausible. :biggrin:
 
In a way, one could see the wavefunction of the entangled pair as a 'cause' for the correlation, could it? However, this seems to me an easy way out.
 
entropy1 said:
In a way, one could see the wavefunction of the entangled pair as a 'cause' for the correlation, could it
"In a way..." seems too weak to me, as the correlation is clearly implied by that wavefunction - an ensemble of particles in the singlet state has to produce those correlations. You prepare a system in a state such that something will happen, then that something happens... There's no great surprise here.
However, this seems to me an easy way out.
That is a matter of personal taste. You may not be satisfied with that resolution, but the minimal statistical crowd generally is.
 
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Nugatory said:
"In a way..." seems too weak to me, as the correlation is clearly implied by that wavefunction - an ensemble of particles in the singlet state has to produce those correlations. You prepare a system in a state such that something will happen, then that something happens... There's no great surprise here.

That is a matter of personal taste. You may not be satisfied with that resolution, but the minimal statistical crowd generally is.
The joint wavefuntion, the singlet state, consists of two product states in superposition defined to be opposite to each other right? So, unless someone could explain to me why not, it seems to me as if correlation in terms of states is rather defined than implied.
 

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