Design and characterization of individual addressing optics based on multi-channel acousto-optic modulator for ¹⁷¹Yb⁺ qubits

We present the design and characterization of individual addressing optics based on a multi-channel acousto-optic modulator (AOM) for trapped ytterbium-171 ions. The design parameters of the individual addressing system were determined based on the tradeoff between the expected crosstalk and the required numerical aperture (NA) of the projection objective lens, and we designed the optical system with moderate NA of 0.24 while keeping the simulated crosstalk to be as low as 10⁻⁶. The individual beams shaped by the projection optics were characterized by two complementary methods: capturing the beams at an intermediate image plane and scanning the ion positions while monitoring the ion-field interactions. The resulting effective beam diameters and separations were approximately 2.34–2.36 μm and 4.31 μm, respectively, and the measured intensity crosstalk was <6×10⁻³, limited by residual aberration.