[摘要]:We predict a dynamic metallization effect where an ultrafast (single-cycle) optical pulse with a less than or similar to 1 V/angstrom field causes plasmonic metal-like behavior of a dielectric film with a few-nm thickness. This manifests itself in plasmonic oscillations of polarization and a significant population of the conduction band evolving on a similar to 1 fs time scale. These phenomena are due to a combination of both adiabatic (reversible) and diabatic (for practical purposes irreversible) pathways.