Cthugha82

Hi,

I just saw your response to my message. Please let me know if you find anything wrong with the earlier version that we have discussed. The other editor appears to be from the Netherlands, and his English is often not clear. So I have cut him some slack. But if the article loses its value to students seeking knowledge, then it it better not to ignore these problems.

Thank you very much for getting involved. P0M (talk) 06:07, 1 February 2014 (UTC)

Welcome!

Hello, Cthugha82, and welcome to Wikipedia! Thank you for your contributions, especially what you did for Delayed choice quantum eraser. I hope you like the place and decide to stay. Here are a few links to pages you might find helpful:

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Any way forward?

I can see no hope of communicating with DP. He confuses a potential for interference with interference itself. He argues backwards. He would argue, it seems, that a ton of hamburger is the same thing as a steer. Each time since these discussions with him began he simply drops an argument that he is not winning and a while later the same unreasonable conclusion comes up again.

His basic mistake is to believe that a photon that is split in the double-slit diaphragm and processed with two quarter wave plates so that the two photon-splits have opposing circular polarization can thereafter superimpose on itself with interference. He is almost correct, because all of the "information" continues to exist, but the "information" splits can't reach each other because of their opposite chirality.

His next mistake is to indicate that mathematically you can fix the chirality mismatch after light exits the two quarter wave plates, but he fails to see that this is a change done to the photon-splits without which they cannot interfere. He says, in effect, "Look! Interference was there all along." What he wants to do could be accomplished by using a half-wave plate on top of one of the two quarter-wave plate. That way there would be consistency between the chirality of the two sets of photon-splits. However, that is also what is accomplished by using the POL1 device in the signal wing of the experimental apparatus. The main difference is that the experimental design uses something that takes two steps to get at all of the photons, mainly because in that way the experimenters can engineer a way to get re-polarization to occur at different distances in time from the initial photon emission.

I can't get through to him, and except for you nobody has ever stepped in to say that my arguments are correct. I think that such reinforcement might be helpful.

Thank you for all the time you have spent on this issue. P0M (talk) 22:02, 8 February 2014 (UTC)

This really seems to be a complicated issue. I tried to make sense of what he wrote here (and elsewhere) and it seems to me that his misconception already starts with the definition of what interference is. He stated somewhere that to him it means something like "adding two waves" which is of course wrong. Unless we are dealing with non-linear optics, it is always possible to simply add two waves. Interference means that some intensity redistribution takes place which allows one to see some fringe pattern or something similar. For the situation with orthogonal polarization you can of course still add waves, but all you will get is a locally varying polarization, but no redistribution of intensity. Based on that misconception, he makes some other somewhat daring assumptions and then arrives at his "classical model". By the way, this was why I suggested relying on sources. I did not intend to flood the article with them, but I suppose it is a good idea to back up the discussions that take place before a consensus is reached with them and assure that content to be added can be verified beforehand. There are so many sources that state the opposite of DP's interpretation of things that it may at least become clear to uninvolved editors that his position is not tenable. I will look at the article in more detail again next week, when I (hopefully) have some more time. Cthugha82 (talk) 13:25, 9 February 2014 (UTC)

Thanks. There are so many unintended consequences due to casual acceptance of terms such as "erase" that it is no wonder that anyone get confused in the beginning. I have never been able to find an appropriate term for what travels down the path from one of the two double slits and what travels down the path from the other slit.

http://www.bottomlayer.com/bottom/kim-scully/kim-scully-web.htm has one way, "Photons from the laser are aimed at the double-slit where they are 'divided,' in the QM sense, between the left slit and the right slit," to at least get started. (By the way, that is a pretty good discussion of the experiment that has been checked by Dr. Kim.) My understanding of the basic experiment, as explained by every source I've ever studied, is that these two "photon splits" arrive at a detection screen and that every point on one copy is displaced from its corresponding part on the other copy by the same amount. With two "photon splits" in circular polarities of opposite chirality that kind of close proximity occurs only twice per cycle, no?

Here is a classical explanation from Francis Weston Sears, Optics, p. 203:

8-1 Interference in thin films. At any point where two or more trains of waves cross one another they are said to interfere. This does not mean that any wave train is impeded by the presence of the others, but refers to the combined effect of them all at the point in question. The principle of superposition states that the resultant displacement at any point and at any instant may be found by adding the instantaneous displacements that would be produced at the point by the individual wave trains if each were present alone. The term "displacement" as used here is a general one....If the waves are electromagnetic, the displacement means the magnitude of the electric or magnetic field intensity.

The index to Optics has only two pages for "photon." On 289ff Sears gives a general discussion of photons and line spectra, describing the quantum mechanical understanding of Einstein et al. in "as if" terms. He is, as always, very accurate in what he says, but he seems unready to risk saying anything that would involve a thorough reworking of all of optics. For "classical physicists" then, interference seems to be a matter of large-scale electromagnetic fields.

As an undergraduate I lived with a group of people, many of whom have become well-recognized physicists, biologists, etc., and they/we would sometimes have roaring arguments over the table after dinner. I could always get them to see each other's point according to what each of them was trying but failing to get across. However, doing that kind of mediation almost has to occur in real time. "Stop! George, you said x and Tony, you said y. You don't realize that you are both saying the same thing, so there is no real argument." I can't do that on a discussion page because I can't interrupt somebody and make him/her explain what something just said really means.

I've ordered some circular polarizers, but I have very little hope of being able to filter out any "photon split pairs" that will interfere with themselves. Not without doing some more polarizing, that is.

By the way, Feynmann says that the distinction between interference and diffraction is not useful since diffraction depends on interference effects. P0M (talk) 15:12, 9 February 2014 (UTC)

What is your assessment on classical interference between oppositelt circularly polarized light waves

Am I mistaken or are you actually giving credence to DP's argument?

If so, can you outline how a clockwise spiral and a counterclockwise spiral can "get together" more than twice per cycle. I can graph a classical electromagnetic wave in space and time, and in fact I only need to open my antique optics text to see a graph there. Is a circularly polarized light wave to be graphed in 3-space or does one have to use some other space? Just labeling the axes would probably do it for me.

Thanks.P0M (talk) 17:35, 10 February 2014 (UTC)

Oh, sorry. Did I give you the impression that there is something to his argument? That was not my intention. The only thing you can combine from the clockwise and counterclockwise spiral is a different polarization, e.g. a linear one (in case that is not clear imagine the superposition of a horizontally polarized wave and a vertically polarized one which are exactly out of phase by 90°. That gives you circular polarization and of course it works the other way round, too. But I suppose that is clear.). However, you cannot change the local amplitude and will therefore never get an interference pattern. Cthugha82 (talk) 19:18, 10 February 2014 (UTC)

No problem. I trust the lab lots more than I trust my "intuition," so I wanted to be sure.P0M (talk) 01:36, 11 February 2014 (UTC)

Draft version of replacement for Delayed choice quantum eraser

User:Patrick0Moran and I have been working on a draft version of a replacement for the existing Delayed choice quantum eraser article. The draft is on the Talk page: Talk:Delayed_choice_quantum_eraser#BEGIN_EDITED_PORTION

We would much appreciate your looking over the draft and making whatever changes that you think are necessary. The section on retrocausality is something that neither Patrick nor I are completely comfortable with. It could use a citation or two that probably you'd already be familiar with. We've been working in "change first, then discuss if necessary" mode. That's been much more efficient than "discuss first, then change", since Patrick and I have had practically no disagreements on what we needed to do.

Thanks in advance for your input! Stigmatella aurantiaca (talk) 14:20, 14 February 2014 (UTC)