Local two-qubit entanglement-annihilating channels

TL;DR

This paper characterizes local entanglement-annihilating channels for two-qubit systems, analyzing their properties, differences from entanglement-breaking channels, and their convexity structure, to understand noise limits for entanglement-based experiments.

Contribution

It provides a detailed characterization of local entanglement-annihilating channels, including their structure and duality, for various types of quantum channels.

Findings

Characterization of local entanglement-annihilating channels for depolarizing, unital, and amplitude-damping channels.

Analysis of the convexity and duality properties of these channels.

Clarification of differences between entanglement-breaking and 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 characterization of so-called local entanglement-annihilating two-qubit channels, which set the maximum permissible noise level allowing to perform entanglement-enabled experiments. The differences, but also subtle relations between entanglement-breaking and local entanglement-annihilating channels are emphasized. A detailed characterization of latter ones is provided for a variety of channels including depolarizing, unital, (generalized) amplitude-damping, and extremal channels. We consider also the convexity structure of local entanglement-annihilating qubit channels and introduce a concept of entanglement-annihilation duality.