Quantum Communication Over Atmospheric Channels: A Framework for Optimizing Wavelength and Filtering

TL;DR

This paper analyzes the optimal wavelength for free-space quantum communication under realistic atmospheric conditions, providing a framework to optimize system parameters and improve quantum networking performance.

Contribution

It introduces a rigorous analysis framework for wavelength selection and filtering requirements in free-space quantum channels considering atmospheric effects.

Findings

Shorter wavelengths are preferable for free-space quantum communication.

The framework aids in designing atmospheric compensation strategies.

Results guide development of more efficient quantum networking systems.

Abstract

Despite quantum networking concepts, designs, and hardware becoming increasingly mature, there is no consensus on the optimal wavelength for free-space systems. We present an in-depth analysis of a daytime free-space quantum channel as a function of wavelength and atmospheric spatial coherence (Fried coherence length). We choose decoy-state quantum key distribution bit yield as a performance metric in order to reveal the ideal wavelength choice for an actual qubit-based protocol under realistic atmospheric conditions. Our analysis represents a rigorous framework to analyze requirements for spatial, spectral, and temporal filtering. These results will help guide the development of free-space quantum communication and networking systems. In particular, our results suggest that shorter wavelengths in the optical band should be considered for free-space quantum communication systems. Our results are also interpreted in the context of atmospheric compensation by higher-order adaptive optics.