Abstract

Delayed-choice erasure is investigated in two-photon two-slit experiments that are generalizations of the micromaser experiment of Scully et al. (Nature 351:111–116, 1991). Applying quantum mechanics to the localization detector, it is shown that erasure with delayed choice in the sense of Scully, has an analogous structure as simple erasure. The description goes beyond probabilities. The EPR-type disentanglement, consisting in two mutually incompatible distant measurements, is used as a general framework in both parts of this study. Two simple coherence cases are shown to emerge naturally, and they are precisely the two experiments of Scully et al. The treatment seems to require the relative-reality-of-unitarily-evolving-state (RRUES) approach. Besides insight in the experiments, this study has also the goal of insight in quantum mechanics. The question is if the latter can be more than just a “book-keeping device” for calculating probabilities as Scully et al. modestly and cautiously claim