We propose a protocol that characterizes the pairwise overlaps of the internal modes of single photons more efficiently than pairwise Hong-Ou-Mandel characterization experiments. This protocol exploits multiphoton interference. We experimentally implement this protocol to characterize three photons. We show that our implementation of the characterization protocol outperforms the pairwise Hong-Ou-Mandel characterization, even if the Hong-Ou-Mandel characterization would have been performed in a noiseless, perfect experiment. We demonstrate this via the Fisher information matrix.
@article{arxiv.2512.04903,
title = {Multiphoton interference outperforms pairwise overlaps for distinguishability characterization},
author = {S. N. van den Hoven and M. C. Anguita and S. Marzban and J. J. Renema},
journal= {arXiv preprint arXiv:2512.04903},
year = {2025}
}