Improving Two-Qubit Gate Fidelity in Arrays of ¹⁷¹Yb 

Neutral-atom arrays have emerged as a leading platform for scalable quantum computing, combining long coherence times, precise optical control of large qubit ensembles, and flexible, reconfigurable connectivity. Achieving fault tolerance, however, requires efficient error detection and correction. Ytterbium offers unique advantages through its metastable-state qubits: leakage to the ground state can be independently detected, converting physical errors into erasures with known locations, while single-photon excitation to Rydberg states enables scalable, high-fidelity two-qubit gates.

We report progress toward improving two-qubit entangling gate fidelities in an array of ¹⁷¹Yb atoms. Our gate performance is primarily limited by the finite Rydberg-state lifetime. Recent upgrades to our UV excitation system enable higher Rabi frequencies, thereby reducing the impact of spontaneous decay during the gate.

Leveraging these improvements, along with state-selective readout and new experimental optimization techniques, we achieve, using an amplitude-robust CZ gate, a two-qubit gate fidelity of F > 0.996 and a post-selected fidelity of F > 0.999. We further compare our measurements with numerical simulations to identify the dominant remaining error sources. These results represent an important step toward scalable, fault-tolerant quantum computing with neutral-atom platforms.