The Scully Duhl quantum eraser experiment uses lasers to excite one of the two atoms (which each releases two photons in opposite directions) where each atom acts as a proxy for a slit in the classical double-slit experiment.
But how do they ensure that the only one atom is excited with the laser at any given time? They can't fire the laser at one atom as the entire point is to ensure that its not known (from the "systems" photon released) which atom was excited.
