The meaning of redundancy and consensus in quantum objectivity

While the terms redundancy and con-sensus are often used as synonyms in the context of quantum objectivity, we show here that these should be understood as two related but distinct notions, that quan-tify different features of the quantum-to -classical transition. We show that the two main frameworks used to measure quan-tum objectivity, namely spectrum broad-cast structure and quantum Darwinism, are best suited to quantify redundancy and consensus, respectively. Furthermore, by analyzing explicit examples of states with nonlocally encoded information, we high-light the potentially stark difference be-tween the degrees of redundancy and con-sensus. In particular, this causes a break in the hierarchical relations between spectrum broadcast structure and quantum Darwin-ism. Our framework provides a new per-spective to interpret known and future re-sults in the context of quantum objectivity, paving the way for a deeper understanding of the emergence of classicality from the quantum realm.

Automated summary

This paper points out that redundancy and consensus are different in the context of quantum objectivity, quantifying different features of the quantum-to-classical transition. The two main frameworks used to measure quantum objectivity, spectrum broadcast structure and quantum Darwinism, are best suited to quantify redundancy and consensus, respectively. By analyzing explicit examples, the paper highlights the potentially stark difference between the degrees of redundancy and consensus, causing a break in the hierarchical relations between spectrum broadcast structure and quantum Darwinism. The framework provided in this paper offers a new perspective to interpret known and future results in the context of quantum objectivity, paving the way for a deeper understanding of the emergence of classicality from the quantum realm.