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arXiv · 2310.06621

The effects of disorder in superconducting materials on qubit coherence

Ran Gao·Feng Wu·Hantao Sun·Jianjun Chen·Hao Deng·Xizheng Ma·Xiaohe Miao·Zhijun Song·Xin Wan·Fei Wang·Tian Xia·Make Ying·Chao Zhang·Yaoyun Shi·Hui-Hai Zhao·Chunqing Deng
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Abstract

Introducing disorderness in the superconducting materials has been considered promising to enhance the electromagnetic impedance and realize noise-resilient superconducting qubits. Despite a number of pioneering implementations, the understanding of the correlation between the material disorderness and the qubit coherence is still developing. Here, we demonstrate a systematic characterization of fluxonium qubits with the superinductors made from titanium-aluminum-nitride with varied disorderness. From qubit noise spectroscopy, the flux noise and the dielectric loss are extracted as a measure of the coherence properties. Our results reveal that the $1/f$ flux noise dominates the qubit decoherence around the flux-frustration point, strongly correlated with the material disorderness; while the dielectric loss remains low under a wide range of material properties. From the flux-noise amplitudes, the areal density ($\sigma$) of the phenomenological spin defects and material disorderness are found to be approximately correlated by $\sigma \propto \rho_{xx}^3$, or effectively $(k_F l)^{-3}$. This work has provided new insights on the origin of decoherence channels within superconductors, and could serve as a useful guideline for material design and optimization.

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Ran Gao, Feng Wu, Hantao Sun, Jianjun Chen, Hao Deng, Xizheng Ma, Xiaohe Miao, Zhijun Song, Xin Wan, Fei Wang, Tian Xia, Make Ying, Chao Zhang, Yaoyun Shi, Hui-Hai Zhao, Chunqing Deng. 2023-10-10. The effects of disorder in superconducting materials on qubit coherence. https://doi.org/10.1038/s41467-025-58745-y

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