We report on the first demonstration of fluorescence detection using single-photon avalanche photodiodes (SPADs) monolithically integrated with a microfabricated surface ion trap. The SPADs are positioned below the trapping positions of the ions, and designed to detect 370 nm photons emitted from single 174Yb+ and 171Yb+ ions. We achieve an ion/no-ion detection fidelity for 174Yb+ of 0.99 with an average detection window of 7.7(1) ms. We report a dark count rate as low as 1.2 kHz at room temperature operation. The fidelity is limited by laser scatter, dark counts, and heating that prevents holding the ion directly above the SPAD. We measure count rates from each of the contributing sources and fluorescence as a function of ion position. Based on the active detector area and using the ion as a calibrated light source we estimate a SPAD quantum efficiency of 24±1%.
@article{arxiv.2105.01235,
title = {Fluorescence Detection of a Trapped Ion with a Monolithically Integrated Single-Photon-Counting Avalanche Diode},
author = {W. J. Setzer and M. Ivory and O. Slobodyan and J. W. Van Der Wall and L. P. Parazzoli and D. Stick and M. Gehl and M. Blain and R. R. Kay and H. J. McGuinness},
journal= {arXiv preprint arXiv:2105.01235},
year = {2021}
}