Basics of observational entropy

TL;DR

This paper introduces observational entropy as a quantum coarse-grained entropy framework, reviewing its formalism, applications in thermodynamics, and connections to quantum correlations, entanglement, and classical theory.

Contribution

It provides a comprehensive overview of observational entropy, including formalism, applications, and generalizations based on POVM measurements, highlighting its role in quantum thermodynamics.

Findings

Observational entropy links to quantum correlations and entanglement.

It generalizes classical coarse-grained entropy to quantum systems.

Applications include thermodynamics and quantum measurement theory.

Abstract

These notes provide a brief primer on the basic aspects of "observational entropy" (also known as "quantum coarse-grained entropy"), a general framework for applying the concept of coarse-graining to quantum systems. We review the basic formalism, survey applications to thermodynamics, make a connection to quantum correlations and entanglement entropy, compare to the corresponding classical theory, and discuss a generalization based on POVM measurements.