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Description
Neutral atoms have emerged as a leading platform for quantum information processing. In particular, alkaline-earth and alkaline-earth-like atoms combine long coherence times, well-characterized hyperfine structure, and precise controllability via external fields. While most current implementations focus on qubits, where two internal states are selected to define an effective two-level system, the rich internal level structure of these atoms also naturally supports multi-level quantum systems. In contrast to two-level systems, these ‘qudits’ increase the information density per computational unit and thereby reduce circuit complexity. They allow for more efficient quantum simulations and offer new possibilities for logical encoding and error-resilient quantum information processing.
In this work, we present a fully optical approach to universal qudit control in trapped neutral atoms at moderate magnetic fields, focusing on the 1S0 → 3P1 transition in 173Yb. We show that universal single-qudit control can be achieved through single-beam Raman transitions between neighboring hyperfine states, together with state-selective phase gates. Our analysis identifies a magic polarization angle of the laser field at which the Raman couplings become state selective, suppress off-resonant mixing, and enable gate rates exceeding 100 kHz.
The same framework is compatible with non-destructive read-out via bright-state cycling transitions on the stretched states, and with two-qudit gates based on the Rydberg blockade mechanism. Taken together, these results establish 173Yb as a promising platform for fast, selective, and scalable control of nuclear-spin qudits, with clear prospects for multilevel quantum computing and quantum simulation.