Twin-Field Quantum Key Distribution requires first-order interference between coherent states sent by Alice and Bob in a mid-station Charlie. In order to obtain stable operation and maximum interferometric visibility, not only phase stabilization but also polarization control is required, especially in optical-fiber setups. In this paper, we propose an experimental setup that simultaneously provides passive stabilization of phase and polarization fluctuations by combining a Sagnac-like interferometer with a "Plug-and-Play" configuration employing Faraday mirrors. Experimental results show a net interferometric visibility maintained around 95.3% during 72 hours of continuous operation, with a standard deviation of 0.47%. The setup can be straightforwardly adapted to a multi-user scenario employing either a star network, a bus topology, or a combination of both.
@article{arxiv.2507.01205,
title = {Passive polarization and phase stabilization scheme for Twin-Field QKD},
author = {Christiano M. S. Nascimento and Felipe Calliari and Guilherme P. Temporão},
journal= {arXiv preprint arXiv:2507.01205},
year = {2025}
}