No-signaling, entanglement-breaking, and localizability in bipartite channels

TL;DR

This paper investigates the structure of bipartite quantum channels, specifically no-signaling channels, and provides a counterexample to a conjecture that all such channels are mixtures of entanglement-breaking and localizable channels.

Contribution

The authors present a general realization scheme for bipartite channels and demonstrate a counterexample to the conjecture about no-signaling channels' composition.

Findings

Counterexample to the conjecture about no-signaling channels

Development of a general realization scheme for bipartite channels

Insight into the structure of quantum channels and their classifications

Abstract

A bipartite quantum channel represents the interaction between systems, generally allowing for exchange of information. A special class of bipartite channels are the no-signaling ones, which do not allow communication. In Ref. [1] it has been conjectured that all no-signaling channels are mixtures of entanglement-breaking and localizable channels, which require only local operations and entanglement. Here we provide the general realization scheme, giving a counterexample to the conjecture.