# Superunsteerability as a quantifiable resource for random access codes assisted by Bell-diagonal states

## TL;DR

This paper introduces superunsteerability as a quantifiable nonclassical resource in separable Bell-diagonal states, demonstrating its advantage in quantum random access codes over classical protocols with shared randomness.

## Contribution

It proposes a measure of superunsteerability, derives its analytical form for Bell-diagonal states, and links it to optimal quantum efficiency in RAC protocols, highlighting its role as a resource.

## Key findings

- Superunsteerability outperforms classical protocols in RAC tasks.
- Analytical expression for superunsteerability in Bell-diagonal states.
- Maximal superunsteerability corresponds to optimal quantum efficiency.

## Abstract

We show how nonclassical correlations in local bipartite states can act as a resource for quantum information processing. Considering the task of quantum random access codes (RAC) through separable Bell-diagonal states, we demonstrate the advantage of superunsteerability over classical protocols assisted with two-bits of shared randomness. We propose a measure of superunsteerability, which quantifies nonclassicality beyond quantum steering, and obtain its analytical expression for Bell-diagonal states in the context of the two- and three-setting steering scenarios that are directly related to the quantum $2 \to 1$ and $3 \to 1$ RAC protocols, respectively. The maximal values of our quantifier yield the optimal quantum efficiency for both of the above protocols, thus showing that superunsteerability provides a precise characterization of the nonclassical resource for implementing RACs with separable Bell-diagonal class of states.