Energy efficient optical tracking for space quantum communication

TL;DR

This paper presents an energy-efficient satellite tracking method for space quantum communication that significantly reduces power consumption while maintaining reliable tracking and minimal impact on quantum key distribution performance.

Contribution

It introduces a novel weak-signal estimation approach using a closed-loop system with Kalman filters and fine steering mirrors for CubeSat tracking.

Findings

Reliable tracking at 34 mW beacon power

Negligible impact on QKD bit error rates

Enhanced power efficiency for quantum payloads

Abstract

Power consumption is a critical constraint for CubeSat based quantum communication, where tracking systems often dominate the onboard power budget. We demonstrate an energy-efficient approach that enables reliable satellite tracking at substantially reduced beacon power by treating tracking as a weak-signal estimation task. Using a closed-loop system with fine steering mirrors and higher-order Kalman filters on ground, we can maintain stable tracking at a transmitted power equivalent to 34 mW over a -60 dB satellite to ground optical channel. Our results show that the resulting penalties on QKD bit error rates and signal-to-noise ratios are negligible, allowing for more efficient power allocation to quantum payloads in CubeSat missions.