Indistinguishability between photons is a key requirement for scalable photonic quantum technologies. We experimentally demonstrate that partly distinguishable single photons can be purified to reach near-unity indistinguishability by the process of quantum interference with ancillary photons followed by heralded detection of a subset of them. We report on the indistinguishability of the purified photons by interfering two purified photons and show improvements in the photon indistinguishability of 2.774(3)\% in the low-noise regime, and as high as 10.2(5) \% in the high-noise regime.
@article{arxiv.2403.12866,
title = {Purifying photon indistinguishability through quantum interference},
author = {Carlos F. D. Faurby and Lorenzo Carosini and Huan Cao and Patrik I. Sund and Lena M. Hansen and Francesco Giorgino and Andrew B. Villadsen and Stefan N. van den Hoven and Peter Lodahl and Stefano Paesani and Juan C. Loredo and Philip Walther},
journal= {arXiv preprint arXiv:2403.12866},
year = {2025}
}