Distributing quantum correlations through local operations and classical resources

TL;DR

This paper introduces a robust protocol for distributing quantum discord across a network using only classical correlations, local unitaries, and measurements, with performance depending on local operations and noise conditions.

Contribution

It presents a novel, physically motivated method for distributing quantum discord with classical correlations, independent of measurement outcomes, and analyzes its scalability and noise effects.

Findings

Quantum discord can be distributed using classical correlations and local operations.

The protocol's performance scales with network size and depends on local operations.

Correlated dephasing noise can enhance discord and fidelity in the protocol.

Abstract

Distributing quantum correlations to each node of a network is a key aspect of quantum networking. Here, we present a robust, physically motivated protocol by which global quantum correlations, as characterized by the discord, can be distributed to quantum memories using a mixed state of information carriers which possesses only classical correlations. In addition, such distribution is done using only bilocal unitary operations and projective measurements, with the degree of discord being measurement-outcome independent. We explore the scaling of the performance of the proposed protocol with the size of the network and illustrate the structure of quantum correlations that are shared by the nodes, showing its dependence on the local operations performed. Finally, we find the counterintuitive result that even more discord can be generated when the resource state undergoes correlated dephasing noise, allowing high fidelities with mixtures of the Bell basis such as Werner states.