We introduce a modification of the standard entanglement swapping protocol where the generation of entanglement between two distant modes is realized and verified using only local optical measurements. We show, indeed, that a simple condition on the purity of the initial state involving also an ancillary mode is sufficient to guarantee the success of the protocol by local measurements {M. Abdi \textit{et al.}, Phys. Rev. Lett. \textbf{109}, 143601 (2012)}]. We apply the proposed protocol to a tripartite optomechanical system where the never interacting mechanical modes become entangled and certified using only local optical measurements.
@article{arxiv.1312.0981,
title = {Continuous variable entanglement swapping and its local certification: entangling distant mechanical modes},
author = {Mehdi Abdi and Stefano Pirandola and Paolo Tombesi and David Vitali},
journal= {arXiv preprint arXiv:1312.0981},
year = {2014}
}