(Quantumness in the context of) Resource Theories

TL;DR

This paper reviews resource theories in quantum physics, explaining how they quantify quantum resources through restricted operations, and explores their applications in entanglement, thermodynamics, and quantumness of correlations.

Contribution

It provides a comprehensive overview of resource theories, including hybrid frameworks, and introduces the concept of quantumness within this unified approach.

Findings

Resource theories unify various quantum phenomena like entanglement and thermodynamics.

Relative entropy serves as a key measure of quantum resources.

Hybrid resource theories enable the study of quantumness of correlations.

Abstract

We review the basic idea behind resource theories, where we quantify quantum resources by specifying a restricted class of operations. This divides the state space into various sets, including states which are free (because they can be created under the class of operations), and those which are a resource (because they cannot be). One can quantify the worth of the resource by the relative entropy distance to the set of free states, and under certain conditions, this is a unique measure which quantifies the rate of state to state transitions. The framework includes entanglement, asymmetry and purity theory. It also includes thermodynamics, which is a hybrid resource theory combining purity theory and asymmetry. Another hybrid resource theory which merges purity theory and entanglement can be used to study quantumness of correlations and discord, and we present quantumness in this more general framework of resource theories.