Quantum discord and remote state preparation

TL;DR

This paper investigates the role of quantum discord in remote state preparation, revealing that discord's usefulness is context-dependent and not universally necessary or sufficient for quantum advantage.

Contribution

It demonstrates that quantum discord is not always a useful resource for remote state preparation, challenging previous assumptions about its universality.

Findings

Some locally produced discord states can aid in remote state preparation.

Certain genuine discordant states do not assist in remote state preparation.

Quantum discord's role as a resource is context-dependent and not universal.

Abstract

The role played by quantum discord in mixed-state computation is widely debated since, in spite of evidence of its importance in creating quantum advantages, even in the absence of entanglement, there are not direct proofs of its necessity in these computational tasks. Recently the presence of discord was shown to be necessary and sufficient for remote state preparation for a broad class of quantum channels [B. Daki\'c et al., Nat. Phys. 8, 666 (2012)]. Here, we show that this property is not universal. There are states whose discord cannot be considered as a quantum resource, since it has been produced locally, that are useful for remote state preparation, and there are bona fide discordant states that are of no help.