Channel Activation of CHSH Nonlocality

TL;DR

This paper demonstrates that certain pairs of CHSH-breaking quantum channels can activate nonlocality when used together, overcoming their individual limitations in distributing nonlocal correlations.

Contribution

It introduces the concept of activation of CHSH-breaking channels, showing that combined channels can violate CHSH inequalities even if individual channels cannot.

Findings

Activation occurs in both uni-directional and bi-directional scenarios.

Certain pairs of CHSH-breaking channels can violate CHSH inequalities when combined.

The work extends understanding of nonlocality activation in quantum channels.

Abstract

Quantum channels that break CHSH nonlocality on all input states are known as CHSH-breaking channels. In quantum networks, such channels are useless for distributing correlations that can violate the CHSH Inequality. Motivated by previous work on activation of nonlocality in quantum states, here we demonstrate an analogous activation of CHSH-breaking channels. That is, we show that certain pairs of CHSH-breaking channels are no longer CHSH-breaking when used in combination. We find that this type of activation can emerge in both uni-directional and bi-directional communication scenarios.