Towards high-fidelity alkali atom entanglement via single-photon Rydberg excitation and fast parallel site-selective optical addressing

Neutral atoms using Rydberg interactions have recently demonstrated entanglement fidelity below the threshold necessary for quantum error correction. In alkali atoms, Rydberg excitation is typically achieved via two-photon transitions. While, in principle, single-photon excitation eliminates errors due to intermediate-state scattering and the Stark shift inherent in the two-photon transition process, previous experimental demonstrations face several challenges. Here we outline an approach to overcome these challenges and present a theoretical error budget indicating a path to entangling-gate infidelity below 10^-3. We also report experimental progress toward implementing single-photon Rydberg excitation and CZ gates with Cs atoms.

 

In addition, we present a fast and scalable method for site-selective optical addressing in large 2D atomic arrays using two orthogonal acousto-optic deflectors (AODs). Multi-tone drive with independently controlled phase, power, and timing generates tailored intensity patterns across a selected row or column for parallel single-qubit operations, followed by rapid scanning for full-array coverage. We discuss machine-learning optimization to suppress intermodulation and an optional galvanometer stage to extend range.