Modulator-free transmitter for quantum key distribution in metropolitan area networks

TL;DR

This paper proposes a simple, modulator-free quantum transmitter for metropolitan area networks, using pulsed optical injection for quantum state preparation, enabling cost-effective and scalable quantum key distribution within cities.

Contribution

It introduces a novel, compact quantum transmitter design that eliminates the need for modulators, suitable for urban QKD networks, and provides experimental validation and security analysis.

Findings

Experimental confirmation of the quantum state preparation method.

Security analysis of the decoy-free three-state QKD protocol.

Potential for simplified, scalable QKD in metropolitan networks.

Abstract

A positive economic effect from the implementation of quantum key distribution (QKD) technology can be achieved only with significant scaling, which involves the deployment of branched metropolitan area networks. The creation of QKD systems suitable for such networks is an important task for the coming years. This paper considers a method for preparing quantum states using pulsed optical injection, which can be used as a basis for a compact modulator-free transmitter ideally suited for QKD at typical distances within a city. Considering the relative proximity between nodes of a MAN, we suggest to abandon the decoy states, which, together with the proposed method of quantum state preparation, allows making the transmitter extremely simple. We report here the results of an experiment confirming the operating principle and provide a security analysis of the three-state decoy-free QKD protocol that can be implemented using such a device.