Entropy exchange, coherent information and concurrence

TL;DR

This paper derives analytic formulas for entropy exchange and coherent information in a simple quantum model, revealing their relationships with concurrence and contrasting their behaviors during quantum evolution.

Contribution

It provides new analytic expressions linking entropy exchange, coherent information, and concurrence, and discusses their implications for quantum system evolution.

Findings

Entropy exchange behaves oppositely to concurrence during evolution.

Coherent information exhibits similar behavior to concurrence.

Analytic expressions clarify relationships among key quantum information measures.

Abstract

For a simple model we derive analytic expressions of entropy exchange and coherent information, from which relations between them and the concurrence are drawn. We find that in the quantum evolution the entropy exchange exhibits behavior \textsl{opposite} to that of the concurrence, whereas the coherent information shows features very similar to those of the concurrence. The meaning of this result for general systems is discussed.