  We explore, by means of inelastic neutron scattering, the extent of changes
in dynamic correlations induced by thermal poling of vitreous $SiO_2$. The
measured vibrational density of states shows an excess of modes in certain
frequency regions as well as a narrowing of the 100 meV peak. These findings
indicate that such alterations cannot be ascribed to the appearance of new well
defined vibrational modes, such as those coming from localized topological
defects, but rather arises from an increase in ordering in the material as
attested in a reduced spread of the inter-tetrahedral angles.
