An integrated photonics platform for high-speed, ultrahigh-extinction, many-channel quantum control

Abstract

High-fidelity control of the thousands to millions of programmable qubits needed for utility-scale quantum computers presents a formidable challenge for control systems. In leading atomic systems, control is optical: UV-NIR beams must be fanned out over numerous spatial channels and modulated to implement gates. While photonic integrated circuits (PICs) offer a potentially scalable solution, they also need to simultaneously feature high-speed and high-extinction modulation, strong inter-channel isolation, and broad wavelength compatibility. Here, we introduce and experimentally validate a foundry-fabricated PIC platform that overcomes these limitations. Designed for Rubidium-87 neutral atom quantum computers, our 8-channel PICs, fabricated on a 200-mm wafer process, demonstrate an advanced combination of performance metrics. At the 795 nm single-qubit gate wavelength, we achieve a mean extinction ratio (ER) of 71.4 $\pm$ 1.1 dB, nearest-neighbor on-chip crosstalk of -68.0 $\pm$ 1.0 dB, and -50.8 $\pm$ 0.2 dB after parallel beam delivery in free-space. This high-performance operation extends to the 420 nm and 1013 nm wavelengths for two-qubit Rydberg gates, showing ERs of 42.4 dB (detector-limited) and 61.5 dB, respectively. The devices exhibit 10-90% rise times of 26 $\pm$ 7 ns, achieve dynamic switching to -60 dB levels within microsecond timescales, and show pulse stability errors at the $10^{-3}$ level. This work establishes a scalable platform for developing advanced large-scale optical control required in fault-tolerant quantum computers and other precision technologies.