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arXiv · 2506.10714

Universal gates for a metastable qubit in strontium-88

Renhao Tao·Ohad Lib·Flavien Gyger·Hendrik Timme·Maximilian Ammenwerth·Immanuel Bloch·Johannes Zeiher
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Abstract

Metastable atomic qubits are a highly promising platform for the realization of quantum computers, owing to their scalability and the possibility of converting leakage errors to erasure errors mid-circuit. Here, we demonstrate and characterize a universal gate set for the metastable fine-structure qubit encoded between the $^3\text{P}_0$ and $^3\text{P}_2$ states in bosonic strontium-88. We find single-qubit gate fidelities of 0.993(1), and two-qubit gate fidelities of 0.9945(6) after correcting for losses during the gate operation. Furthermore, we present a novel state-resolved detection scheme for the two fine-structure states that enables high-fidelity detection of qubit loss. Finally, we leverage the existence of a stable ground state outside the qubit subspace to perform mid-circuit erasure conversion using fast destructive imaging. Our results establish the strontium fine-structure qubit as a promising candidate for near-term error-corrected quantum computers, offering unique scaling perspectives.

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Renhao Tao, Ohad Lib, Flavien Gyger, Hendrik Timme, Maximilian Ammenwerth, Immanuel Bloch, Johannes Zeiher. 2025-06-12. Universal gates for a metastable qubit in strontium-88. https://doi.org/10.1103/gj3b-5ngl

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