Preparing Remote States for Genuine Quantum Networks

TL;DR

This paper introduces and experimentally verifies a new quantum resource called RSP capability, which ensures genuine quantum network performance surpasses classical methods, highlighting the limitations of quantum discord as an indicator.

Contribution

The paper defines and demonstrates the RSP capability as a practical resource for quantum networks, surpassing classical strategies and clarifying quantum discord's role.

Findings

RSP capability outperforms classical emulation in quantum networks

Quantum discord does not guarantee nonclassical RSP

Experiment shows transition between classical and nonclassical RSP

Abstract

Quantum networks typically comprise quantum channels, repeaters, and end nodes. Remote state preparation (RSP) allows one end node to prepare the states of the other end nodes remotely. While quantum discord has recently been recognized as necessary for RSP, it does not guarantee the practical implementation of RSP in quantum networks surpasses any classical method. Herein, we theoretically introduce and experimentally study a quantum resource that we call the RSP capability. This resource validates all the static and dynamic elements required to enable genuine quantum networks where the RSP's implementation can outperform any classical emulation of entanglement- and qubit-unitaries-free strategies, including the static resources of Einstein-Podolsky-Rosen pairs and the dynamic resources of quantum channels and repeaters. Our experiment measures the RSP capability to demonstrate the transition between classical and nonclassical RSP depending on the photon-pair qualities. It shows that quantum discord does not confirm a nonclassical RSP, but the RSP capability does. These results help reveal the quantum advantages that emerge when networking RSP is in play.