Quantum Coherence and Intrinsic Randomness

TL;DR

This paper explores the relationship between quantum coherence, intrinsic randomness, and quantum correlations, revealing how different coherence measures relate to quantum discord and measurement uncertainty.

Contribution

It provides a quantum perspective on coherence measures and establishes a connection between intrinsic randomness, coherence, and quantum discord.

Findings

Coherence of formation quantifies measurement uncertainty.

Relative entropy of coherence measures distillable coherence.

The gap between these measures equals quantum discord.

Abstract

The peculiar uncertainty or randomness of quantum measurements stems from coherence, whose information-theoretic characterization is currently under investigation. Under the resource theory of coherence, it is interesting to investigate interpretations of coherence measures and the interplay with other quantum properties, such as quantum correlations and intrinsic randomness. Coherence can be viewed as the resource for the intrinsic randomness in the measurement outcomes of a state in the computational basis. We observed in our previous work that the coherence of formation, which measures the asymptotic coherence dilution rate, indeed quantifies the uncertainty of a (classical) correlated party about the system measurement outcome. In this work, we re-derive the result from a quantum point of view and then connect the intrinsic randomness to the relative entropy of coherence, another important coherence measure that quantifies the asymptotic distillable coherence. Even though there does not exist bound coherent states, these two intrinsic randomness quantified by coherence of formation and the relative entropy of coherence are different. Interestingly, we show that this gap is equal to the quantum discord, a general form of quantum correlations, in the state of the system of interest and the correlated party, after a local measurement on the former system.