Robustness of Measurement, discrimination games and accessible information

TL;DR

This paper introduces the robustness of measurement as a resource-theoretic quantifier of informativeness, linking it to operational advantages in quantum discrimination games and single-shot information measures.

Contribution

It defines a new robustness measure for quantum measurements, demonstrating its operational significance and connection to accessible information and coherence in quantum information theory.

Findings

Robustness quantifies how much noise makes a measurement uninformative.

It provides an operational advantage in quantum state discrimination tasks.

Links robustness measures to single-shot information concepts.

Abstract

We introduce a way of quantifying how informative a quantum measurement is, starting from a resource-theoretic perspective. This quantifier, which we call the robustness of measurement, describes how much `noise' must be added to a measurement before it becomes completely uninformative. We show that this geometric quantifier has operational significance in terms of the advantage the measurement provides over guessing at random in an suitably chosen state discrimination game. We further show that it is the single-shot generalisation of the accessible information of a certain quantum-to-classical channel. Using this insight, we also show that the recently-introduced robustness of coherence is the single-shot generalisation of the accessible information of an ensemble. Finally we discuss more generally the connection between robustness-based measures, discrimination problems and single-shot information theory.