We propose and analyze experiments designed to probe the way in which the measurement process (the presence of a detector) influences the investigated system. These experiments are based on the fact that number states of the radiation field can be generated by the use of the micromaser and cavity quantum electrodynamics. It is shown that ‘‘which-path’’ (particle) information rules out interference (wave) effects due to the system-detector correlations and not due to a randomization of phase. Specific experiments based on neutron interferometry and quantum-beat techniques taken together with the micromaser are suggested and analyzed.

• Received 3 October 1988

DOI:https://doi.org/10.1103/PhysRevA.39.5229