Continuous variable quantum key distribution channel emulator for the SPOQC mission

TL;DR

This paper presents a novel optical channel emulator designed to simulate satellite-to-ground FSO links with dynamic losses, enabling realistic testing of quantum communication payloads for satellite missions.

Contribution

The work introduces a new optical channel emulator capable of replicating satellite-to-ground channel dynamics for quantum key distribution testing in a lab setting.

Findings

Successfully emulates atmospheric turbulence effects

Accurately reproduces satellite trajectory variations

Benchmarks quantum key distribution performance

Abstract

In a free space optical (FSO) communication link from satellite to ground, the losses in the channel will be dynamic. Thus, the characterization of the FSO channel is of great importance and this can be emulated in the lab to evaluate the realistic performance of a satellite payload. In this work, we introduce a novel optical channel emulator capable of replicating these dynamics, especially for Low Earth Orbit based CubeSats. We demonstrate its ability to accurately emulate a satellite-to-ground optical communications channel under various atmospheric turbulence strengths, satellite trajectories, and optical ground station parameters at a given optical wavelength of interest. Our satellite channel emulator was designed to test and benchmark the performance of the continuous variable quantum key distribution payload for the Satellite Platform for Optical Quantum Communications mission - an in-orbit demonstrator for the UK's Quantum Communication Hub, to be launched in early 2026.