Why don't the interference plots of the delayed-choice quantum eraser go to zero?

[tomhiggins]

In the original paper on the delayed-choice quantum eraser by Kim et al. [Phys. Rev. Lett. 84, 1 (2000)], the plots of the joint detection rates shown in Figures 3 & 4 do not go to zero. Not even close. I've always wondered about that. The authors don't address it, and I haven't seen any explanation of it elsewhere. In the classic double-slit experiment, intensities go to zero (or close to it) at the minima of the interference pattern.

Let me just say that I believe I have a fairly simple explanation for why the plots don't go to zero, but I hesitate to share it here because the links to my two papers on this are located on my website. I don't want to trigger some arbitrary spam filter or violate any rules of this forum.

However, I have found that my attempts to answer this key question gave me much more insight into the workings of the experiment. I would love to hear your thoughts on this and share mine, if you're interested...

 

[Nugatory]

Let me just say that I believe I have a fairly simple explanation for why the plots don't go to zero, but I hesitate to share it here because the links to my two papers on this are located on my website. I don't want to trigger some arbitrary spam filter or violate any rules of this forum.

The forum rules don’t allow posting personal work that has not been published in an appropriate peer-reviewed journal…. So yes, you are right about not linking to your papers.
Your question - why don’t the counts go to zero? - is of course in bounds for discussion here.

 

[tomhiggins]

Noted and understood...

 

[Cthugha]

In the original paper on the delayed-choice quantum eraser by Kim et al. [Phys. Rev. Lett. 84, 1 (2000)], the plots of the joint detection rates shown in Figures 3 & 4 do not go to zero. Not even close. I've always wondered about that. The authors don't address it, and I haven't seen any explanation of it elsewhere. In the classic double-slit experiment, intensities go to zero (or close to it) at the minima of the interference pattern.

But the authors address these issues in the paper. When they explain equation 6, they state the following:
"Finally, after we take into account the finite size of the detectors and the divergence of the pump beam, the interference visibility is found to be in satisfactory agreement with observation."

These are the main effects that reduce the visibility of the interference (which means: why the minimum is not at zero). If you want to avoid wasting time on speculating and want to know the exact details on pretty much everything that influences coincidence count rates in spatial correlations in PDC, a very thorough explanation of many influences and effects is given in this paper:
S.P. Walborn et al., "Spatial Correlations in Parametric Down-Conversion", Physics Reports 495, 87 (2010)
Link to Paper
Link to ArXiv version

See, e.g., figure 9 for an account of how detector aperture size influences interference visibility.