Individual addressability for short-wavelength transitions through visible integrated photonics with free-space nonlinear conversion

Integrated photonic devices offer a path to perform site-addressable quantum gates on thousands of atomic systems, pushing beyond the limits of bulk optical modulators. Integrated photonic platforms with transparency in the blue and ultraviolet—wavelengths required for many quantum gate protocols—are less developed than platforms for the visible or telecom. Here, we propose and implement a strategy to convert light from arrays of thin-film-lithium-niobate integrated photonic modulators to blue and ultraviolet wavelengths via sum-frequency generation with a strong pump beam. Using this strategy, we enable multi-channel, GHz modulation, from 300 nm to 900 nm with a single device. We discuss implications for Rydberg gates on neutral atom qubits.