Progress Towards Integration of an Optical Cavity with an Individually-Addressed Trapped Ion Chain

Scaling up the number of qubits is one of the main challenges in realizing useful trapped-ion based quantum computers. Optical cavities are a potential route to improving connectivity and entanglement rates between ions. High-finesse cavities however, have proved challenging to integrate with ions due to dielectric charging of the mirrors. In contrast, lower-finesse optical cavities offer relatively easy alignment and potentially smaller charging effects. In this poster we present progress on the axial integration of a low-finesse optical cavity with a surface-electrode Ba⁺ ion trap as an alternative approach to scaling to more ions. Our design offers high optical access and is compatible with individual addressing of ions for quantum computing and simulation. We characterize the heating rates of a Roadrunner trap from Sandia National Labs and report the finesse of our in-vacuum optical cavity. Additionally, we present the performance of a custom mechanical assembly for cavity alignment and stabilization. We aim to use the cavity to create a fast and deterministic photonic coupling between spatially separated ion-chains. From there, further scaling is possible with an array of cavities which would allow longer-range entanglement across chains [1].

This work is supported by the National Science Foundation's Quantum Leap Challenge Institute for Robust Quantum Simulation under Award OMA-2120757. This work is further supported by a collaboration between the US DOE and other Agencies. This material is based upon work supported by the DOE, Office of Science, National Quantum Information Science Research Centers, Quantum Systems Accelerator.

[1] J. Ramette et al., PRX Quantum, 3, 010344 (2022).