# Converting multilevel nonclassicality into genuine multipartite entanglement

## TL;DR

This paper develops a formal framework for converting nonclassicality, such as quantum superposition, into genuine multipartite entanglement, establishing reversible transformations and quantitative relations between these quantum resources.

## Contribution

It introduces a general resource-theoretic formalism for converting nonclassicality into multipartite entanglement, including explicit protocols and quantitative resource relations.

## Key findings

- Reversible transformation between nonclassicality and entanglement is always possible.
- Conversion relates multilevel coherence to multipartite entanglement quantitatively.
- Equality between nonclassicality and entanglement resources is established using fidelity-based measures.

## Abstract

Characterizing genuine quantum resources and determining operational rules for their manipulation are crucial steps to appraise possibilities and limitations of quantum technologies. Two such key resources are nonclassicality, manifested as quantum superposition between reference states of a single system, and entanglement, capturing quantum correlations among two or more subsystems. Here we present a general formalism for the conversion of nonclassicality into multipartite entanglement, showing that a faithful reversible transformation between the two resources is always possible within a precise resource-theoretic framework. Specializing to quantum coherence between the levels of a quantum system as an instance of nonclassicality, we introduce explicit protocols for such a mapping. We further show that the conversion relates multilevel coherence and multipartite entanglement not only qualitatively, but also quantitatively, restricting the amount of entanglement achievable in the process and in particular yielding an equality between the two resources when quantified by fidelity-based geometric measures.