Integrated focusing grating coupler deep-adjoint-designed for multi-ion manipulation and readout

Laser manipulation of ions is crucial for high-fidelity quantum information processors. Increasing the number of qubits improves quantum computer performance. However, scaling optical signal delivery to multiple ions is challenging. Here, we propose integrating photonic circuits into trapped-ion chips for efficient optical addressing of 88Sr+ ions and full qubit control. Combining machine learning with electromagnetic optimization reduces design costs and accelerates component discovery. We demonstrate a deep-adjoint-based multicolor focusing grating coupler (FGC) for precise ion control, achieving high radiation efficiency and minimal crosstalk. Compact FGCs outperform the state-of-the-art couplers and have potential applications in quantum computers, sensors, and optical clocks.