Optimizing Rydberg Gates for Logical Qubit Performance

Improving the fidelity of two-qubit Rydberg blockade gates is one of the key challenges for the continued development of neutral atom quantum processors. Here, we employ quantum optimal control methods to construct a family of Rydberg blockade gates that are robust against two common, major imperfections: intensity inhomogeneity and Doppler shifts. These gates can be implemented with a global laser pulse, whose phase is modulated in time to achieve the desired robustness. While being robust against intensity inhomogeneity and Doppler shifts, the gates show an increased susceptibility to Rydberg decay errors. To quantify this tradeoff, we evaluate the gate fidelity for the example of erasure-biased metastable ¹⁷¹Yb qubits, and find that the robust gates significantly outperform existing gates for moderate or large imperfections. We then consider the logical performance of these gates in the context of an error correction code. In this case, we observe that the robust gates outperform existing gates even for very small imperfections, because they maintain the native large bias towards erasure errors. Our results significantly reduce the laser stability and atomic temperature requirements to achieve fault-tolerant quantum computing with neutral atoms.