Delayed Choice Quantum Eraser Experiment Revisited: Causality and Informational Coherence

An operationally well-defined delayed-choice quantum-eraser experiment is proposed, realizing a genuine delayed choice within presently available quantum-optical technology. A multimode quantum memory supplies a controlled and verifiable delay, ensuring that the choice operation is applied strictly after the observation event. Electronic single-photon interference detection measurements furnish a direct statistical discriminator between the causal and informational coherence hypotheses, based solely on marginal detection statistics and without any post-selection.