aM. de Labachelerie, K. Nakagawa, and M. Ohtsu, Opt. Lett. 19, 840 (1994)
bJ. Ye, L. S. Ma, and J. L. Hall, Opt. Lett. 21, 1000 (1996)
cC. Cohen-Tannoudji, J. Dupont-Roc, and G. Grynberg. ``Atom-Photon Interactions'', Wiley Interscience, New York (1992).
MOSHINSKY´S RESULTS ON ”DIFFRACTION IN TIME” ARE EXTENDED TO THE CASE OF A RECTANGULAR PULSE. BESIDES INTERFERENCE EFFECTS OF THE TYPE STUDIED BY MOSHINSKY THERE APPEARS ALSO THE WELL KNOWN QUANTUM MECHANICAL SPREADING EFFECT. RISE TIME AND MONOCHROMATICITY REQUIREMENTS SEEM TO PRECLUDE THE POSSIBILITY OF EXPERIMENTAL OBSERVATION OF THE INTERFERENCE EFFECTS, SO THAT THEY NEED NOT BE TAKEN INTO ACCOUNT IN NEUTRON VELOCITY SELECTORS. THE DETECTION OF THE SPREADING, WICH IS SUBJECT TO WEAKER REQUIREMENTS, WOULD PROVIDE A DIRECT TEST OF THE UNCERTAINTY RELATION.