Duality principle is 'safe and sound'

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Discussion Overview

The discussion revolves around the duality principle in quantum mechanics, specifically focusing on an experiment that seemingly measured which-way information while also observing interference patterns. Participants explore the implications of this experiment and its interpretations, referencing previous studies and articles related to wave-particle duality and complementarity.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant references a 2012 experiment by Ralf Menzel and colleagues that measured which-way information while observing interference, questioning how both could occur simultaneously.
  • Another participant critiques the interpretation of the 2012 paper, arguing it did not claim to break complementarity and highlights the presence of two modes of different wave vectors that allow for interference even with which-way information.
  • A different participant expresses skepticism about the accuracy of the reporting on the experiment, suggesting that the findings may have been misrepresented.
  • One participant seeks clarification on whether the new article implies that the original findings regarding which path the photon took while obtaining an interference pattern are incorrect.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of the experiment and its implications for the duality principle. There is no consensus on the accuracy of the claims made in the original paper or the subsequent articles discussing it.

Contextual Notes

Some participants note that the original paper's claims may have been overstated or misinterpreted, and there is uncertainty regarding the implications of the findings on established principles in quantum mechanics.

StevieTNZ
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http://phys.org/news/2014-08-duality-principle-safe-apparent-violation.html

It seems an experiment was performed back in 2012 that measured which-way information, but also found interference. (I may have come across it at the time, but cannot recall reading about it from memory.) How could this be so?
In their 2012 version of the famous Young two-split experiment, Ralf Menzel and his colleagues at the University of Potsdam simultaneously determined a photon's path and observed high contrast interference fringes created by the interaction of waves from the two slits.

However, as the article states, Robert Boyd found out the cause of this:
Boyd and his colleagues discovered that the German physicists had inadvertently sampled the sections of high visibility with greater probability than the other sections. While only a handful of photons produced high visibility interference, they used the entire set of photons to determine the predictability of knowing through which slit they had passed.
 
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That is an incredibly annoying way of overselling.

The 2012 paper (R. Menzel, D. Puhlmann, A. Heuer, and W. P. Schleich.
Wave-particle dualism and complementarity unraveled by
a dierent mode. Proceedings of the National Academy of
Sciences, 109(24):9314{9319, 2012., http://www.pnas.org/content/109/24/9314.abstract?sid=af26123d-7825-4b52-bdae-beab95cf46f9) never actually claimed that it breaks complementarity or stuff like that. They had two modes of different wave vector present at the double slit, which means that even if you only have one slit, you still have two probability amplitudes for getting a photon to the detector that can interfere, if it is intrinsically indistinguishable which mode each photon will end up in.

The current paper (http://arxiv.org/abs/1402.6487) now shows that the previous paper does not prove a claim that was never made in that paper. I need to remember that trick for "selling" my next manuscripts. I must admit that their analysis of interference visibility variations is nice. I am still somewhat puzzled why the paper made it to PNAS, though.
 
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StevieTNZ said:
http://phys.org/news/2014-08-duality-principle-safe-apparent-violation.html

It seems an experiment was performed back in 2012 that measured which-way information, but also found interference. (I may have come across it at the time, but cannot recall reading about it from memory.) How could this be so?However, as the article states, Robert Boyd found out the cause of this:
Hey I was just talking about the same article and how they found which path the photon took while obtaining an interference pattern. So it turns out that they don't? is that what the new article is saying?
 

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