Converting qubit relaxation into erasures with a single fluxonium

• URL: http://arxiv.org/abs/2601.11086v1
• Date: Fri, 16 Jan 2026 08:39:04 GMT
• Title: Converting qubit relaxation into erasures with a single fluxonium
• Authors: Chenlu Liu, Yulong Li, Jiahui Wang, Quan Guan, Lijing Jin, Lu Ma, Ruizi Hu, Tenghui Wang, Xing Zhu, Hai-Feng Yu, Chunqing Deng, Xizheng Ma,
• Abstract summary: Qubits that experience predominantly erasure errors offer distinct advantages for fault-tolerant operation.<n>We realize erasure conversion in a single fluxonium operated at zero flux, where the logical state is encoded in its 0-2 subspace.<n>Post-selection on non-erasure outcomes results in more than four-fold increase of the logical lifetime, from $193$s to $869$s.
• Score: 14.396916509257132
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Qubits that experience predominantly erasure errors offer distinct advantages for fault-tolerant operation. Indeed, dual-rail encoded erasure qubits in superconducting cavities and transmons have demonstrated high-fidelity operations by converting physical-qubit relaxation into logical-qubit erasures, but this comes at the cost of increased hardware overhead and circuit complexity. Here, we address these limitations by realizing erasure conversion in a single fluxonium operated at zero flux, where the logical state is encoded in its 0-2 subspace. A single, carefully engineered resonator provides both mid-circuit erasure detection and end-of-line (EOL) logical measurement. Post-selection on non-erasure outcomes results in more than four-fold increase of the logical lifetime, from $193~μ$s to $869~μ$s. Finally, we characterize measurement-induced logical dephasing as a function of measurement power and frequency, and infer that each erasure check contributes a negligible error of $7.2\times 10^{-5}$. These results establish integer-fluxonium as a promising, resource-efficient platform for erasure-based error mitigation, without requiring additional hardware.

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