Multi-Hop Quantum Key Distribution with Passive Relays over Underwater Turbulence Channels

TL;DR

This paper explores multi-hop underwater quantum key distribution using passive relays to extend communication range despite underwater turbulence, analyzing system parameters and environmental effects.

Contribution

It introduces a passive-relay based multi-hop QKD scheme for underwater channels, analyzing its performance and key system parameters without requiring measurements at relays.

Findings

Passive relays enable longer underwater QKD links.

Aperture size and detector FOV significantly impact range.

Performance varies with different oceanic conditions.

Abstract

Absorption, scattering, and turbulence experienced in underwater channels severely limit the range of quantum communications. In this paper, to overcome range limitations, we investigate a multi-hop underwater quantum key distribution (QKD) where intermediate nodes help the key distribution between the source and destination nodes. We consider deployment of passive-relays which simply redirect the qubits to the next relay node or receiver without any measurement. Based on near-field analysis, we present the performance of relay-assisted QKD scheme in clear ocean under different atmospheric conditions. We further investigate the effect of system parameters (aperture size and detector field-of-view) on the achievable distance.