Using a single circular Rydberg atom, we have prepared two modes of a superconducting cavity in a maximally entangled state. The two modes share a single photon. This entanglement is revealed by a second atom probing, after a delay, the correlations between the two modes. This experiment opens interesting perspectives for quantum information manipulation and fundamental tests of quantum theory.
@article{arxiv.quant-ph/0105062,
title = {Controlled entanglement of two field modes in a Cavity Quantum Electrodynamics experiment},
author = {A. Rauschenbeutel and P. Bertet and S. Osnaghi and G. Nogues and M. Brune and J. M. Raimond and S. Haroche},
journal= {arXiv preprint arXiv:quant-ph/0105062},
year = {2009}
}