Optimized ancillary drive for fast Rydberg entangling gates

Reaching fast and robust two-qubit gates with low infidelities has been an outstanding challenge for the long-term goal of useful quantum computers. Typically, optimizing the pulse shapes can minimize the gate infidelity and improve its robustness to certain types of errors; yet it remains incapable of speeding up the gate execution time, which is fundamentally restricted by the attainable Rabi frequency in a realistic setup. In this work, we develop a fast implementation of two-qubit controlled-Z (CZ) gates using an optimized ancillary drive to enhance the two-photon Rabi frequency between the ground and Rydberg states. This ancillary drive can work in an error-robustness framework without increasing the original gate infidelity in the absence of the drive. Considering the experimentally feasible parameters for ⁸⁷Rb atoms, we demonstrate that the execution time required for such CZ gates can be shortened by more than 30% as compared to standard two-photon protocols, increasing the gate fidelity above 0.9954 by taking account of all relevant error sources. Our results reduce the high-power laser requirement and unlock the potential toward fast, high-fidelity quantum operations for large-scale quantum computation with neutral atoms.