Entanglement Generation by Delocalized Single-Photon Addition

We report an experimental realization of entangled states obtained by applying a superposition of single-photon creation operations between two uncorrelated temporal modes populated by coherent states of the same amplitude. Such entangled states of light can be populated with a large number of photons while preserving their non classical correlations. Besides their importance from the fundamental point of view to study quantum effects in large-scale systems, these states are found to be surprisingly robust against losses [1] and thus well suited to travel over long distances and to be stored in atomic ensembles.