# Approximate broadcasting of quantum correlations

## TL;DR

This paper characterizes two-sided quantum discord through bilocal broadcasting and formulates optimal broadcasting fidelities as efficiently computable semidefinite programs, advancing understanding of quantum correlations.

## Contribution

It provides a full operational characterization of two-sided quantum discord and introduces SDP formulations for optimal broadcasting fidelities, enabling practical computation.

## Key findings

- Operational characterization of two-sided quantum discord.
- SDP formulations for optimal broadcasting fidelities.
- Evaluation of broadcasting fidelities in specific cases.

## Abstract

Broadcasting quantum and classical information is a basic task in quantum information processing, and is also a useful model in the study of quantum correlations including quantum discord. We establish a full operational characterization of two-sided quantum discord in terms of bilocal broadcasting of quantum correlations. Moreover, we show that both the optimal fidelity of unilocal broadcasting of the correlations in an arbitrary bipartite quantum state and that of broadcasting an arbitrary set of quantum states can be formulized as semidefinite programs (SDPs), which are efficiently computable. We also analyze some properties of these SDPs and evaluate the broadcasting fidelities for some cases of interest.