Entanglement activation and the robustness of quantum correlations

We show that the usefulness of a state as an activator in teleportation protocols is equivalent to the robustness of its entanglement to noise. The robustness of entanglement of a bipartite state sigma is linked to the maximum increase in the fidelity of teleportation of any other state when sigma is used as an extra resource. On the one hand, this connection gives an operational meaning to the robustness of entanglement. On the other hand, it shows that the activation capability-which has a central role as an operational way of quantifying bound entangled states-can be estimated experimentally by measuring entanglement witnesses.