Recent investigations suggest that the use of non-classical states of light, such as entangled photon pairs, may open new and exciting avenues in experimental two-photon absorption spectroscopy. Despite several experimental studies of entangled two-photon absorption (eTPA), there is still a heated debate on whether eTPA has truly been observed. This interesting debate has arisen, mainly because it has been recently argued that single-photon-loss mechanisms, such as scattering or hot-band absorption may mimic the expected entangled-photon linear absorption behavior. In this work, we focus on transmission measurements of eTPA, and explore three different two-photon quantum interferometers in the context of assessing eTPA. We demonstrate that the so-called N00N-state configuration is the only one amongst those considered insensitive to linear (single-photon) losses. Remarkably, our results show that N00N states may become a potentially powerful tool for quantum spectroscopy, and place them as a strong candidate for the certification of eTPA in an arbitrary sample.
@article{arxiv.2208.11387,
title = {Witnessing Entangled Two-Photon Absorption via Quantum Interferometry},
author = {Áulide Martínez-Tapia and Samuel Corona-Aquino and Chenglong You and Rui-Bo Jin and Omar S. Magaña-Loaiza and Shi-Hai Dong and Alfred B. U'Ren and Roberto de J. León-Montiel},
journal= {arXiv preprint arXiv:2208.11387},
year = {2022}
}