A scaled trapped-ion quantum computer will require efficient fluorescence collection across a large area. Here we propose and demonstrate a compact monolithically integrated system featuring a metalens fabricated on the backside of a surface ion trap. A 40×100 μm aperture enables a simulated point-source collection efficiency of 0.91% and a measured point-source detection efficiency of 0.58%. Increasing the aperture area to 40×600 μm boosts the simulated collection efficiency to 3.17%−comparable to that of a conventional objective with a numerical aperture of 0.35. Further improvements are possible by co-optimizing the electrode and aperture geometry. An undercut of the electrode substrate at the aperture ensures a large distance between the ion and dielectric substrate without compromising collection efficiency. The metalens directly collimates the collected fluorescence, eliminating the need for a high numerical aperture objective. An array of such readout zones will offer a compact, scalable solution for high-fidelity parallel readout in next-generation trapped-ion quantum processors.
@article{arxiv.2507.23071,
title = {Scalable Ion Fluorescence Collection Using a Trap-Integrated Metalens},
author = {Hae Lim and Johannes E. Fröch and Christian M. Pluchar and Arka Majumdar and Sara L. Mouradian},
journal= {arXiv preprint arXiv:2507.23071},
year = {2025}
}