A striking spectral-modulation effect has been observed by means of a
proper postselection procedure under conditions where the spatial shif
t of the wave trains greatly exceeds the coherence length of the neutr
on beams traversing an interferometer. It is shown that Schrodinger-ca
t-like states are created by the superposition of two coherent states
generated in the interferometer. These entangled states exhibit, under
certain circumstances, characteristic squeezing phenomena, indicating
a highly nonclassical behavior. Analogies with optical experiments ar
e discussed.