Amplification, Decoherence, and the Acquisition of Information by Spin Environments

TL;DR

This paper demonstrates how quantum Chernoff information quantifies the amplification of information in spin environments, elucidating the emergence of classical reality through quantum Darwinism and enabling easier experimental testing.

Contribution

It introduces quantum Chernoff information as a measure of information amplification in spin environments, advancing understanding of quantum Darwinism in realistic settings.

Findings

Redundant information acquisition is typical in spin environments.

Quantum Chernoff information captures amplification behavior, including oscillations.

Results facilitate experimental testing of quantum Darwinism, e.g., with nitrogen vacancies.

Abstract

Quantum Darwinism recognizes the role of the environment as a communication channel: Decoherence can selectively amplify information about the pointer states of a system of interest (preventing access to complementary information about their superpositions) and can make records of this information accessible to many observers. This redundancy explains the emergence of objective, classical reality in our quantum Universe. Here, we demonstrate that the amplification of information in realistic spin environments can be quantified by the quantum Chernoff information, which characterizes the distinguishability of partial records in individual environment subsystems. We show that, except for a set of initial states of measure zero, the environment always acquires redundant information. Moreover, the Chernoff information captures the rich behavior of amplification in both finite and infinite spin environments, from quadratic growth of the redundancy to oscillatory behavior. These results will considerably simplify experimental testing of quantum Darwinism, e.g., using nitrogen vacancies in diamond.