Fluorescence Detection of a Trapped Ion with a Monolithically Integrated Single-Photon-Counting Avalanche Diode

TL;DR

This paper demonstrates fluorescence detection of trapped ions using integrated single-photon detectors with high fidelity, low dark counts, and a quantum efficiency of 24%, advancing ion detection technology.

Contribution

First integration of monolithic single-photon avalanche diodes with a microfabricated ion trap for fluorescence detection.

Findings

Achieved 0.99 ion/no-ion detection fidelity.

Dark count rate as low as 1.2 kHz at room temperature.

Estimated SPAD quantum efficiency of 24%.

Abstract

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 $^{174}$Yb$^+$ and $^{171}$Yb$^+$ ions. We achieve an ion/no-ion detection fidelity for $^{174}$Yb$^+$ 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$\pm$1%.