We present an adaptive procedure for aligning quantum non-locality experiments without any knowledge of the two-qudit state shared by the participating parties. The quantum state produced by the source, its unitary evolution as well as the actual measurement bases remain unknown to both parties at all times. The entanglement of the quantum state helps establish desired correlations between individual measurement bases of the two distant parties. We implement the procedure in a fiber-based quantum key distribution (QKD) setup with polarization-entangled photons, where we do not rely on any additional alignment tools such as lasers or polarizers. In a QKD scenario the procedure can be done without any additional measurements as those that are performed regardless.
@article{arxiv.2310.03468,
title = {State independent QKD},
author = {Robert Kindler and Johannes Handsteiner and Jaroslav Kysela and Kuntuo Zhu and Bo Liu and Anton Zeilinger},
journal= {arXiv preprint arXiv:2310.03468},
year = {2024}
}