Memory-Assisted Quantum Key Distribution with a Single Nitrogen Vacancy Center

TL;DR

This paper proposes a simplified memory-assisted quantum key distribution scheme using a single nitrogen-vacancy center, enhancing secure communication over longer distances with fewer memory requirements.

Contribution

It introduces a novel MA-MDI-QKD scheme utilizing only one quantum memory, making quantum communication more practical and scalable.

Findings

The scheme outperforms existing QKD systems in rate and distance.

It is resilient to memory errors, improving reliability.

Extension to quantum repeater networks enables longer-distance secure communication.

Abstract

Memory-assisted measurement-device-independent quantum key distribution (MA-MDI-QKD) is a promising scheme that aims to improve the rate-versus-distance behavior of a QKD system by using the state-of-the-art devices. It can be seen as a bridge between current QKD links to quantum repeater based networks. While, similar to quantum repeaters, MA-MDI-QKD relies on quantum memory (QM) units, the requirements for such QMs are less demanding than that of probabilistic quantum repeaters. Here, we present a variant of MA-MDI-QKD structure that relies on only a single physical QM: a nitrogen-vacancy center embedded into a cavity where its electronic spin interacts with photons and its nuclear spin is used for storage. This enables us to propose a simple but efficient MA-MDI-QKD scheme resilient to memory errors and capable of beating, in terms of rate and reach, existing QKD demonstrations. We also show how we can extend this setup to a quantum repeater system, reaching, thus, larger distances.