LOW-CONTRAST AND LOW-COUNTING-RATE MEASUREMENTS IN NEUTRON INTERFEROMETRY

Here we discuss the limits of the recognizability of neutron interference patterns either observed in low-contrast measurements or when collecting very few neutrons only. Low contrast can be caused by a strong beam attenuation or by a large phase shift applied to one beam path. Stochastic and deterministic cases have different influences on the interference pattern, which can be interpreted as a different wavelike or particlelike behavior of the system. Measurements of interference patterns with very few neutrons only are related to the phase-particle-number uncertainty relation, which is discussed on the basis of stochastic and quantum theory arguments. Analogies between coherent-state behavior known in atomic physics and the behavior of neutrons in an interferometer are discussed also. © 1990 The American Physical Society.