NONDISPERSIVE PHASE OF THE AHARONOV-BOHM EFFECT

An essential signature of the topological nature of all Aharonov-Bohm type phases is that they are nondispersive, i.c., independent of the v elocity (wavelength) of the interfering particles. This implies that a n Aharonov-Bohm phase shift can greatly exceed the usual limit given b y the coherence length of the interfering beams. We report the results of a polarized neutron experiment demonstrating this property for a s pin-rotation analog of the scalar Aharonov-Bohm effect.