Continuous-Variable Measurement-Device-Independent Quantum Key Distribution in Free-Space Channels

TL;DR

This paper investigates the feasibility of continuous-variable measurement-device-independent quantum key distribution over free-space optical channels, analyzing turbulence effects and finite-size key rates for various communication scenarios.

Contribution

It provides the first detailed analysis of CV-MDI-QKD in free-space channels, including turbulence effects and finite-size key rate calculations for different link configurations.

Findings

Finite-size key rates are achievable over free-space links.

Turbulence effects significantly impact key distribution performance.

Both horizontal and slant path links are viable for secure quantum communication.

Abstract

The field of space communications is the realm of communication technologies where diffraction and atmospheric effects, both of which contribute to loss and noise, become overriding. The pertinent questions here are how and at which rate information (secret keys) can be securely transferred (shared) among users under such supposedly severe circumstances. In the present work we study continuous-variable (CV) quantum key distribution (QKD) in a measurement-device-independent (MDI) configuration over free-space optical (FSO) links. We assess the turbulence regime and provide a composable finite-size key rate analysis of the protocol for FSO links. We study both short-range, horizontal communication links as well as slant paths to, e.g., high-altitude platform station (HAPS) systems.