Advances in the development of a polarization tracking system for the Q-ANSER mission.

Q-ANSER is a planned two-satellite mission aiming to demonstrate secure quantum communication links between satellites in low Earth orbit (LEO). The mission will validate key technologies for future global quantum networks, focusing on polarization-based quantum key distribution (QKD). A central element of Q-ANSER is its polarization control and tracking system, which ensures stable polarization states under dynamic orbital conditions. At its core lies the Polarization Control Device (PCD), capable of real-time polarization correction to minimize quantum bit error rates (QBER) and maintain secure key rates. This presentation will introduce the mission concept and highlight the design, operation, and expected performance of the PCD-based polarization tracking system.