Trapped ions are a leading system for realizing quantum information processing (QIP). Most of the technologies required for implementing large-scale trapped-ion QIP have been demonstrated, with one key exception: a massively parallel ion-photon interconnect. Arrays of microfabricated phase Fresnel lenses (PFL) are a promising interconnect solution that is readily integrated with ion trap arrays for large-scale QIP. Here we show the first imaging of trapped ions with a microfabricated in-vacuum PFL, demonstrating performance suitable for scalable QIP. A single ion fluorescence collection efficiency of 4.2 +/- 1.5% was observed, in agreement with the previously measured optical performance of the PFL. The contrast ratio between the ion signal and the background scatter was 23 +/- 4. The depth of focus for the imaging system was 19.4 +/- 2.4 {\mu}m and the field of view was 140 +/- 20 {\mu}m. Our approach also provides an integrated solution for high-efficiency optical coupling in neutral atom and solid state QIP architectures.
@article{arxiv.1006.4192,
title = {Imaging trapped ions with a microfabricated lens for quantum information processing},
author = {Erik W. Streed and Benjamin G. Norton and Andreas Jechow and Till J. Weinhold and David Kielpinski},
journal= {arXiv preprint arXiv:1006.4192},
year = {2011}
}