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I think this was the most simple DCQE with double slits: http://arxiv.org/pdf/quant-ph/0106078v1.pdf

For a short summary: the experimental setup uses an entangled pair of photons (p and s). The s-photons goes through a double slit which signs the photons with the which-way information using quarter-wave-plates. On the p-photons we can choose if we erase the ww info by placing a polarizer - this will let go through only half of the photons and erase the polarization info of the p-photons and this way the s-photons too. The s-photons are detected in Ds detector. There is a coincidence counter too, which can be used to find out which p-photon detection is the EPR pair of an s-photon (and vice versa).

My explanation:

I found that at the secondary detector (Ds) we can find a Gaussian noise and this fact is

**never**influenced by the polarizer POL1 regardless if placed or not near before the primary detector. The eraser works this way: using the polarizer POL1 with Dp data and and with the coincidence counter data we can find the

**subset**of the s-photons which subset draws an interference pattern. These s-photons are the half of all s-photons. The other half of s-photons draws an other interference pattern and the sum of these two patterns produces the Gaussian noise pattern.

Question 1: Am I right that all of the Ds data

**always**draws a Gauss distribution?

Qusetion 2: am I wrong at any point regarding the above explanation?

Now I try to explain my problem. Let's modify the experiment setup a little bit. Increase the distance between the two slits so the non-interferencing pattern will split into two Gauss distribution. Can we do this? I think we can. With this setup we have two choice:

1 - not using the eraser (POL1) we got the two Gaussian pattern

2 - using the eraser we have to got the double slit interference pattern by choosing the appropriate s-photon subset (based on Dp and coincidence counter data)

The second choice is problematic because a two-slit interference pattern should contain some constructive fringes behind the "wall" which is between the two slits (at x=0 place). But we have two Gaussian distribution with low intensity at x=0. We can not find any subset of s-photons to draw the double slit interference pattern.

Question 3: Can we increase the distance between the slits to see two Gaussian distribution in Ds (not using POL1)?

Question 4: If we use POL1 with this setup we see the same distribution in Ds?

Question 5: What kind of interference pattern subset can be found in this case?

Thats enough for starting. Thanks in advance for any help.