We present a complete method to characterize multiphoton detectors with a small overall detection efficiency. We do this by separating the nonlinear action of the multiphoton detection event from linear losses in the detector. Such a characterization is a necessary step for quantum information protocols with single and multiphoton detectors and can provide quantitative information to understand the underlying physics of a given detector. This characterization is applied to a superconducting multiphoton nanodetector, consisting of an NbN nanowire with a bowtie-shaped subwavelength constriction. Depending on the bias current, this detector has regimes with single and multiphoton sensitivity. We present the first full experimental characterization of such a detector.
@article{arxiv.1110.5442,
title = {Complete experimental characterization of a superconducting multiphoton nanodetector},
author = {J. J. Renema and G. Frucci and Z. Zhou and F. Mattioli and A. Gaggero and R. Leoni and M. J. A. de Dood and A. Fiore and M. P. van Exter},
journal= {arXiv preprint arXiv:1110.5442},
year = {2016}
}