Multipartite entanglement evolution under separable operations

We study how multipartite entanglement evolves under the paradigm of separable operations, which include the local operations and classical communication as a special case. We prove that the average ``decay'' of entanglement induced by a separable operation is measure independent (among SL-invariant ones) and state independent: The ratio between the average output entanglement and the initial entanglement is solely a function of the separable operation, regardless of the input state and of the SL-invariant entanglement measure being used. We discuss the ``disentangling power'' of a quantum channel and show that it exhibits a similar state invariance as the average entanglement decay ratio. Our Rapid Communication significantly extends the bipartite results of Horodecki and Horodecki, Quantum Inf. Comput. 10, 901 (2010), Konrad et al., Nat. Phys. 4, 99 (2008), and Tiersch et al., Phys. Rev. Lett. 101, 170502 (2008) as well as the multipartite one of Gour, Phys. Rev. Lett. 105, 190504 (2010), all of the previous work being restricted to one-sided or particular noise models.