Fundamental Limits on Gate-Laser Scattering Errors in Barium-133

Barium-133 is a promising trapped-ion qubit for large scale quantum computing with easily accessible laser frequencies, robust state preparation, and high fidelity readout. Past theoretical calculations placed a limit on Ba⁺ stimulated Raman Gate errors due to off resonant photon scattering from the qubit hyperfine ground state to auxillary electron states that limited two-qubit gate fidelities to around 0.999. However, examining the scattering errors with an expanded model for the Raman gate and scattering processes reveals that the error rates can be orders of magnitude lower at readily available gate laser wavelengths. We present a study of measured scattering errors and relate these errors to the ultimate fidelity limits of laser-driven gates in the ¹³³Ba⁺ qubit.