Measurement-device-independent quantum communication with an untrusted source

TL;DR

This paper introduces a secure measurement-device-independent quantum key distribution network that operates with an untrusted source, demonstrating its practicality and near-optimal key rates through simulations.

Contribution

It presents the first complete security proof for MDI-QKD with an untrusted source and shows its feasibility with real-world imperfections.

Findings

Key generation rate close to ideal MDI-QKD in simulations

Feasibility of quantum networks with low-cost devices

Untrusted source does not compromise security

Abstract

Measurement-device-independent quantum key distribution (MDI-QKD) can provide enhanced security, as compared to traditional QKD, and it constitutes an important framework for a quantum network with an untrusted network server. Still, a key assumption in MDI-QKD is that the sources are trusted. We propose here a MDI quantum network with a single untrusted source. We have derived a complete proof of the unconditional security of MDI-QKD with an untrusted source. Using simulations, we have considered various real-life imperfections in its implementation, and the simulation results show that MDI-QKD with an untrusted source provides a key generation rate that is close to the rate of initial MDI-QKD in the asymptotic setting. Our work proves the feasibility of the realization of a quantum network. The network users need only low-cost modulation devices, and they can share both an expensive detector and a complicated laser provided by an untrusted network server.