Idler behavior post signal detection in DCQE

San K

Refer to the delayed choice quantum eraser (DCQE) ...for example the kim paper

http://en.wikipedia.org/wiki/Delayed...quantum_eraser

i have a few questions, to understand this better,

1. Once the signal photon has been detected at D0,

can the path of idler photon be determined in terms of probability?

2. for 1 above we would have to wait for the idler to arrive at one of the detectors so that it can be compared/correlated at the co-incidence counter?

3. can the path of the idler be manipulated (for which way or no which way) once the signal photon has been detected (at D0)?

4. let's say we modify the experiment in which:

a) we have do not have which way information (from the idler) at the time the signal photon strikes D0.
b) after the signal photon has struck DO, we manipulate the path of the idler such that we have which way information.
c) we repeat this same procedure/experiment say a million times (with single photons sent at a time of course)

now since we did not have which-way information at the time the signal photon was detected, we would expect an interference pattern.

however the idler would have been manipulated (as per our experiment) to show which way path information.

Question: don't we now have idler and signal saying different things?

Question: is it possible to manipulate the path of the idler (same as question 3, just asking it again), after detection of signal?

Question: can the path of idler be manipulated at all?

Thanks

San K

in short what i am trying to say is:

1. once signal photon has been detected at D0, idler path is also "fixed" probabilistically

please say true or false

2. if you try to manipulate the idler path (once signal photon as been detected) you have violated the boundaries/rules/setup of the experiment and its no longer valid

please put true or false