Accessible information in quantum measurement

TL;DR

This paper provides a simple proof of the Kholevo bound, which limits accessible information in quantum measurements, extending it to sequential measurements using quantum entropies, with a minimal physical model and intuitive diagrammatic approach.

Contribution

It offers a straightforward proof of the Kholevo bound and its extension to sequential measurements, avoiding environmental decoherence assumptions and using an intuitive diagrammatic method.

Findings

Proof of the Kholevo bound presented

Extension to sequential measurements demonstrated

Minimal physical model without environmental decoherence

Abstract

The amount of information that can be accessed via measurement of a quantum system prepared in different states is limited by the Kholevo bound. We present a simple proof of this theorem and its extension to sequential measurements based on the properties of quantum conditional and mutual entropies. The proof relies on a minimal physical model of the measurement which does not assume environmental decoherence, and has an intuitive diagrammatic representation.