We experimentally study entangled two-photon absorption in Rhodamine 6G as a function of the spatial properties of a high flux of broadband entangled photon pairs. We first demonstrate a key signature dependence of the entangled two-photon absorption rate on the type of entangled pair flux attenuation: linear, when the laser pump power is attenuated, and quadratic, when the pair flux itself experiences linear loss. We then perform a fluorescence-based Z-scan measurement to study the influence of beam waist size on the entangled two-photon absorption process and compare this to classical single- and two-photon absorption processes. We demonstrate that the entangled two-photon absorption shares a beam waist dependence similar to that of classical two-photon absorption. This result presents an additional argument for the wide range of contrasting values of quoted entangled two-photon absorption cross-sections of dyes in literature.
@article{arxiv.2206.00500,
title = {Spatial properties of entangled two-photon absorption},
author = {D. Tabakaev and A. Djorovic and L. La Volpe and G. Gaulier and S. Ghosh and L. Bonacina and J. -P. Wolf and H. Zbinden and R. T. Thew},
journal= {arXiv preprint arXiv:2206.00500},
year = {2022}
}