Interference seen in a member of an entangled pair

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Discussion Overview

The discussion revolves around the implications of measuring the spin of entangled electrons in a double-slit experiment, particularly focusing on whether such measurements affect the interference pattern observed in the experiment. Participants explore the theoretical framework of quantum mechanics, entanglement, and the potential for faster-than-light communication.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants propose that if neither electron's spin is measured, the right electron should show an interference pattern, while measuring the left electron's spin would eliminate this pattern due to the acquisition of which-slit information.
  • Others argue that the interference pattern is only visible through data analysis and that individual measurements may appear random, with correlations only becoming apparent when considering both particles together.
  • A participant notes that measuring one particle's spin does not determine the spin of the other particle in a definitive way after measurement, as it returns to a probabilistic state.
  • Another participant emphasizes that measurements made in one lab cannot affect the results in another lab, reinforcing the idea that no faster-than-light communication is possible through this setup.
  • There is a discussion about the implications of measuring spins and how it affects the observed outcomes in terms of interference patterns, with some suggesting that contradictions arise if one assumes interference can coexist with knowledge of which-slit information.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the implications of the measurements on the interference pattern. There are competing views on whether measuring the spin affects the observed results and the nature of the correlations between the entangled particles.

Contextual Notes

Limitations include the dependence on the definitions of measurement and entanglement, as well as the unresolved nature of how interference patterns manifest in relation to measurements of entangled particles.

  • #61
Have you studied at the actual mathematical analysis of how erasing the information in the apparatus is supposed to restore interference

Please see my post in the thread How do you determine that a particle is/was entangled?
 
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  • #62
One more try at realistic explanation.

Say the same experiment http://arxiv.org/abs/quant-ph/9810080
There they say "The coincidence peak was nearly noise-free (SNR > 100) with approximately Gaussian shape and a width (FWHM) of about 2 ns. All data reported here were calculated with a window of 6 ns."
If we draw coincidence graph not for all data but only for 45° coincidences and if it has not one peak but two peaks with equal height (conditional +- and -+ peaks) then ... well, case solved.
 

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