Quantum correlations between two cavity QED systems coupled by a mechanical resonator Jhon Edinson Ramírez-Muñoz, Juan Pablo Restrepo Cuartas and Herbert Vinck-Posada Eur. Phys. J. B, 91 11 (2018) 268 Published online: 01 November 2018 DOI: 10.1140/epjb/e2018-90438-4