Local two-qubit entanglement-annihilating channels

Abstract

We address the problem of the robustness of entanglement of bipartite systems (qubits) interacting with dynamically independent environments. In particular, we focus on the characterization of so-called local entanglement-annihilating (EA) two-qubit channels, which set the maximum permissible noise level allowing us to perform entanglement-enabled experiments. The differences, but also the subtle relations, between entanglement-breaking and local EA channels are emphasized. A detailed characterization of the latter ones is provided for a variety of channels including depolarizing, unital, (generalized) amplitude-damping, and extremal channels. We also consider the convexity structure of local EA qubit channels and introduce a concept of EA duality.