Measurement-device-independent quantum key distribution with nitrogen vacancy centers in diamond

TL;DR

This paper evaluates nitrogen vacancy centers in diamond as quantum memories for measurement-device-independent quantum key distribution, showing potential advantages over no-memory systems at certain distances with current technology.

Contribution

It demonstrates the feasibility of using cavity-enhanced NV centers in MA-MDI-QKD to surpass no-memory systems within 300-500 km distances.

Findings

Moderate cavity enhancement enables NV centers to outperform no-memory QKD.

Key rate advantage is achievable between 300 km and 500 km with current system parameters.

Major error sources like dark current and decoherence are incorporated into the analysis.

Abstract

Memory-assisted measurement-device-independent quantum key distribution (MA-MDI-QKD) has recently been proposed as a possible intermediate step towards the realization of quantum repeaters. Despite its relaxing some of the requirements on quantum memories, the choice of memory in relation to the layout of the setup and the protocol has a stark effect on our ability to beat existing no-memory systems. Here, we investigate the suitability of nitrogen vacancy (NV) centers, as quantum memories, in MA-MDI-QKD. We particularly show that moderate cavity enhancement is required for NV centers if we want to outperform no-memory QKD systems. Using system parameters mostly achievable by today's state of the art, we then anticipate some total key rate advantage in the distance range between 300 km and 500 km for cavity-enhanced NV centers. Our analysis accounts for major sources of error including the dark current, the channel loss, and the decoherence of the quantum memories.