# Contextual advantage for state-dependent cloning

## TL;DR

This paper demonstrates that quantum state-dependent cloning exhibits nonclassical behavior by violating a noncontextuality inequality, highlighting a quantum advantage over classical models.

## Contribution

It proves that the optimal fidelity in quantum state-dependent cloning cannot be explained by noncontextual models and derives an experimentally testable noncontextuality inequality.

## Key findings

- Quantum theory predicts higher cloning fidelity than noncontextual models.
- A noise-robust noncontextuality inequality is derived.
- Quantum violation of the inequality confirms nonclassicality.

## Abstract

A number of noncontextual models exist which reproduce different subsets of quantum theory and admit a no-cloning theorem. Therefore, if one chooses noncontextuality as one's notion of classicality, no-cloning cannot be regarded as a nonclassical phenomenon. In this work, however, we show that there are aspects of the phenomenology of quantum state cloning which are indeed nonclassical according to this principle. Specifically, we focus on the task of state-dependent cloning and prove that the optimal cloning fidelity predicted by quantum theory cannot be explained by any noncontextual model. We derive a noise-robust noncontextuality inequality whose violation by quantum theory not only implies a quantum advantage for the task of state-dependent cloning relative to noncontextual models, but also provides an experimental witness of noncontextuality.