We present a novel optical device based on an integrated system of micro-lenses and single mode optical fibers. It allows to collect and direct into many modes two photons generated by spontaneous parametric down conversion. By this device multiqubit entangled states and/or multilevel qu-dit states of two photons, encoded in the longitudinal momentum degree of freedom, are created. The multi-path photon entanglement realized by this device is expected to find important applications in modern quantum information technology.
@article{arxiv.0809.4575,
title = {Multi-path entanglement of two photons},
author = {A. Rossi and G. Vallone and A. Chiuri and F. De Martini and P. Mataloni},
journal= {arXiv preprint arXiv:0809.4575},
year = {2009}
}