Universal optimal broadband photon cloning and entanglement creation in one-dimensional atoms

We study an initially inverted three-level atom in the $\ensuremath{\Lambda}$ configuration embedded in a waveguide, interacting with a propagating single-photon pulse. Depending on the temporal shape of the pulse, the system behaves either as an optimal universal cloning machine or as a highly efficient deterministic source of maximally entangled photon pairs. This quantum transistor operates over a wide range of frequencies and can be implemented with today's solid-state technologies.