Analysis of satellite-to-ground quantum key distribution with adaptive optics

TL;DR

This paper investigates how adaptive optics can optimize satellite-to-ground quantum key distribution by modeling atmospheric turbulence effects and estimating secret key rates under various realistic conditions.

Contribution

It provides a comprehensive analysis of adaptive optics impact on quantum key distribution performance using realistic turbulence data and different encoding schemes.

Findings

Adaptive optics improves coupling efficiency in satellite-to-ground links.

Secret key rates are significantly affected by turbulence strength and telescope size.

Advanced AO techniques enhance practical quantum communication performance.

Abstract

Future quantum communication infrastructures will rely on both terrestrial and space-based links integrating high-performance optical systems engineered for this purpose. In space-based downlinks in particular, the loss budget and the variations in the signal propagation due to atmospheric turbulence effects impose a careful optimization of the coupling of light in single-mode fibers required for interfacing with the receiving stations and the ground networks. In this work, we perform a comprehensive study of the role of adaptive optics (AO) in this optimization, focusing on realistic baseline configurations of prepare-and-measure quantum key distribution (QKD), with both discrete and continuous-variable encoding, and including finite-size effects. Our analysis uses existing experimental turbulence datasets at both day and night time to model the coupled signal statistics following a wavefront distortion correction with AO, and allows us to estimate the secret key rate for a range of critical parameters, such as turbulence strength, satellite altitude and ground telescope diameter. The results we derive illustrate the interest of adopting advanced AO techniques in several practical configurations.