We study an initially inverted three-level atom in the 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.
@article{arxiv.1208.5817,
title = {Universal optimal broadband photon cloning and entanglement creation in one dimensional atoms},
author = {D. Valente and Y. Li and J. P. Poizat and J. M. Gerard and L. C. Kwek and M. F. Santos and A. Auffeves},
journal= {arXiv preprint arXiv:1208.5817},
year = {2012}
}