磁通量子比特中的准粒子诱导跃迁
Quasiparticle-induced transitions in a fluxonium qubit
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中文总结 AI 辅助
研究磁通量子比特中准粒子诱导跃迁，通过可控片上准粒子注入测量相关速率，发现模拟跃迁速率需考虑超导能隙不对称性，理论与实验比较限制了准粒子贡献并解释了相关差异。
中文摘要 AI 辅助
准粒子是超导量子比特中显著的退相干源，但在磁通量子比特中其效应极难分离。与跨导量子比特不同，磁通量子比特对偏移电荷不敏感，无法进行准粒子隧穿的电荷宇称检测。我们通过在可控的片上准粒子注入下测量磁通量子比特中的激发和去激发速率来应对这一挑战。我们表明，要准确模拟准粒子诱导跃迁速率的外部磁通量依赖性，必须考虑约瑟夫森结上超导能隙的不对称性。理论与实验的比较限制了结阵列和小结的相对准粒子贡献，并有助于解释先前报道的这两个电路元件的准粒子密度界限之间的差异。
英文摘要
Quasiparticles are a prominent decoherence source in superconducting qubits, but their effects are notoriously difficult to isolate in fluxonium. Unlike the transmon, fluxonium is insensitive to offset charge, precluding charge-parity detection of quasiparticle tunneling. We address this challenge by measuring the excitation and de-excitation rates in a fluxonium qubit under controlled on-chip quasiparticle injection and isolating the quasiparticle-induced contribution by subtracting the background transition rates. We show that to accurately model the external magnetic flux dependence of the quasiparticle-induced transition rates, it is necessary to account for the superconducting gap asymmetry across the Josephson junctions. A comparison between theory and experiment constrains the relative quasiparticle densities in the small junction and the junction array and helps explain previously reported discrepancies between the bounds on the quasiparticle densities inferred for these two circuit elements.
