Scalable Ion Fluorescence Collection Using a Trap-Integrated Metalens

TL;DR

This paper presents a compact, integrated metalens system on a surface ion trap that significantly improves fluorescence collection efficiency, enabling scalable, high-fidelity parallel readout for trapped-ion quantum computers.

Contribution

It introduces a monolithically integrated metalens on a surface ion trap, enhancing fluorescence collection efficiency and scalability for quantum computing applications.

Findings

Simulated collection efficiency of 0.91% for a small aperture.

Measured detection efficiency of 0.58%.

Boosting aperture size increases efficiency to 3.17%, comparable to conventional objectives.

Abstract

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$\times$100 $\mu$m 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$\times$600 $\mu$m 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.