A Dual Metastable-State Encoding Architecture for Quantum Processing with ${}^{1}71\text{mathrmYb}$ Atom Arrays

Abstract

Neutral-atom arrays combine scalable qubit registers, long coherence times, flexible optical control, and strong Rydberg-mediated entangling interactions, making them a promising platform for quantum information processing. However, physical error rates remain a challenge, and fault-tolerant quantum error correction (QEC) requires repeated mid-circuit measurement and reset of ancilla qubits without disturbing nearby data qubits. This requirement introduces significant control and architectural overhead, making qubit encoding an important architectural decision. Here, we propose a dual metastable-state qubit encoding for ${}^{171}\mathrm{Yb}$ atoms that utilizes two independent qubit subspaces in the $(6s6p){}^3{\mathrm{P}}_0$ and $(6s6p){}^3{\mathrm{P}}_2$ manifolds. The ${}^3{\mathrm{P}}_0$ manifold provides a long-coherence nuclear-spin (NS) qubit suitable for storage and arithmetic operations, while the ${}^3{\mathrm{P}}_2$ manifold provides a hyperfine-spin (HF) qubit, with ${\Delta }_{\mathrm{HF}}=2\pi \times 6.7\mathrm{GHz}$, that enables fast Raman operations and direct state-selective imaging. Coherent shelving between the two metastable manifolds connects the qubit subspaces, allowing operations to be assigned to spectrally distinct processor zones. We simulate single-qubit and two-qubit gate fidelities in ${}^3{\mathrm{P}}_2$, as well as coherent shelving between the HF and NS qubit subspaces. We incorporate these physical-level estimates into an architectural resource estimation and logical-level simulation. Our approach integrates mid-circuit measurements and fast qubit operations within a single-species platform, providing a versatile framework for future fault-tolerant quantum computing with neutral-atom qubits.