Enhancing dual-band stabilization for twin-field quantum key distribution using laser frequency stabilization

Abstract Twin-field quantum key distribution (TF-QKD) has attracted considerable attention in quantum communication for the extension of secure communication distance. In TF-QKD, precise photon phase control is required and has been realized using dual-band stabilization (DBS). In this study, we performed residual phase noise reduction in DBS using laser frequency stabilization. The achieved frequency stability of the light sources was better than 1 × 10 −12 when the averaging time is larger than 1 s, indicating that the laser frequency variation was less than 200 Hz at 1.5 μm. The integrated phase noise at 1 s was less than 200 mrad, and the corresponding quantum bit error rate at 1 s was less than 1% after applying laser frequency stabilization. This result demonstrates that the stringent phase stability requirements in TF-QKD can be achieved without relying on complex optical frequency combs, enabling a simpler and more cost-effective experimental setup.