# Talk:Englert–Greenberger–Yasin duality relation

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## Experimental setup

Is this article talking about the classic double slit experiment or not? It seems to me that the relation derived is valid for this, but the text mentions lenses and what not which seem superfluous. --Michael C. Price talk 13:38, 16 November 2006 (UTC)

I believe it is. The topic as a whole is a sub-topic of coherence theory, which deals with coherence and fringe visibility of different light sources. The physics of coherence is of separation of time or space (which is just a statement about speed of propagation of waves.) The book on Optics by Hecht and Zajac provides a solid introductory overview. Lenses show up typically to get the brightness big enough in the lab to be able to measure the things. What should probably be done is to contrast this relation against the framework of semi-coherent light sources. Other notable subtopics of coherence theory are Hanbury-Brown and Twiss effect. linas 15:36, 16 November 2006 (UTC)

## Can meaning of "D" parameter be explained conceptually?

It's fairly clear what D means in the extreme cases of D=0 and D=1, but I wonder if there's any way to explain what it means for intermediate values in terms that aren't too technical? It's defined in terms of the absolute value of the probability it went through one slit vs. the probability it went through the other, but what can this even mean in quantum mechanics if we're not using an interpretation with hidden variables? Orthodox QM doesn't say there's a definite truth about which slit it went through on each trial, so how does one define the "probability" it went through a given slit in a trial where no detectors were present at the slits, and D is less than 1 but greater than 0? The third-to-last paragraph says "If we detect the photon at (F), we don't know where the photon would have been detected in the aperture plane and D = 0 characterizes our ignorance"--so does that mean the probabilities PA and PB are the probabilities the phoon "would have been detected" at one slit vs. the other if there had been detectors present there? Hypnosifl (talk) 02:17, 20 June 2011 (UTC)

## Statistical?

I think we have to be careful in saying the the wavefunction is a statistical construct. I thought that may been what born thought but the idea of the wave nature of molecules is more extensive than simply a distribution based off of lack of knowledge like much of statistics. 128.255.75.223 (talk) 15:03, 12 December 2012 (UTC)aepd

## Where is Yasin?

The inequality should correctly be called Englert-Greenberger-Yasin inequality. The name of the page should also be appropriately modified. The inequality was derived by Greenberger & Yasin, and Englert in two independent papers. There is not reason why Yasin's name should not be included. — Preceding unsigned comment added by Tabish q (talkcontribs) 08:41, 20 May 2014 (UTC)