[quote author=Fu-Kwun Hwang link=topic=2231.msg8295#msg8295 date=1310542685]
1. Do you mean there is a continue beam of atom moving toward a screen with two slits?[/quote]
One excited atom at a time being sent towards the screen.[/quote]

[quote author=Fu-Kwun Hwang link=topic=2231.msg8295#msg8295 date=1310542685]2. Does atom move with the same speed v (or random speed),separated by the same distance(or randomly)?[/quote]
Each excited atom moves at the same speed. The distance between the source and screen stays the same each time.

[quote author=Fu-Kwun Hwang link=topic=2231.msg8295#msg8295 date=1310542685]3. What do you mean by "detector click or not"??? How to decide?[/quote]
When only one shutter is opened, either the detector will click or not (randomly, of course obeying QM statistics). So 50% of the time a photon will be found in the top cavity; 50% of the time a photon will be found in the bottom cavity. Say we open the top shutter, and the atom had passed through the top slit, then the detector will click because a photon would be in the top cavity. If, say we had opened the bottom shutter instead, the detector won't click, which would tell us the atom took the top path and there is a photon in the top cavity.

When erasure occurs, i.e. when we open both shutters at the same time 50% of the time we get a click, and 50% of the time we don't get a click (each event occurs randomly), which is in accord with Quantum Mechanics predictions.

BOTH one shutter being opened, and both shutters being opened at the same time, will be done, for each atom that hits the final screen. Of course whether we get a click or not is random each time, but in accordance with the predictions of Quantum Theory.

[quote author=Fu-Kwun Hwang link=topic=2231.msg8295#msg8295 date=1310542685]4. What kind of information need to be recorded/shown?[/quote]
Record where each atom hits the screen. Take two copies of that screen now, and then for copied screen 1 we'll find out which slit the atom went through, and mark the point on the screen in accordance with the key in the image I posted in a previous post. For copied screen 2, we'll erase the information, and mark the point on the screen again in accordance with the key I provided.

Each time a new atom hits the screen, leave the previous marking on the copied screen (with its coloured key point as per eraser or which-slit info) and repeat the steps done to colour the previous marking, for the new marking.


[b]So in effect, each time we send an atom to the screen, we are doing two different experiments for the same atom, at seperate times. Each time we send an atom to the screen, we are finding out which slit it went through, and then another experiment to plot what the final screen pattern would look like HAD we done erasure instead of finding out which slit info.[/b]

[i]Question:[/i] Will the simulation, when built, reproduce the predictions of Quantum Mechanics?

This image might help: it is the original discussion of the though experiment itself which we're going to republicate. Not sure if you've seen it before or know about it.

[img]http://img.photobucket.com/albums/v608/steviet/Delayed-ChoiceQuantumEraserExperiment.jpg[/img]