High Efficiency Light Collection for Use in a Modular Quantum Network

Remote entanglement of ions is useful as a tool in the development of a scalable quantum network. To generate entanglement, we collect and fiber couple the emitted photons from ions in separate vacuum chambers. We aim to achieve diffraction-limited light collection, imaging or fiber coupling with 10 % of the emitted photons through the use of a number of supporting technologies. The objective lens is designed to work at 0.6 NA for both Yb⁺ and Ba⁺ light spanning wavelengths from 370 nm to 650 nm. We then correct residual aberrations from the vacuum chamber and lens system using a deformable mirror. A Shack-Hartmann wavefront sensor and Zernike polynomial decomposition of intensity can be used for initial settings of the mirror, and closed-loop optimization is performed using feedback from photon counts through the fiber.

This work is supported by the ARO with funding from the IARPA LogiQ program, the AFOSR, the ARO MURI on Modular Quantum Circuits, the AFOSR MURI on Quantum Transduction, and the ARL Center for Distributed Quantum Information.