发表机构
Center for Functional Nanomaterials, Brookhaven National Laboratory; Material Measurement Laboratory, National Institute of Standards and Technology; National Synchrotron Light Source II, Brookhaven National Laboratory（布鲁克海文国家实验室功能纳米材料中心; 美国国家标准与技术研究院材料测量实验室; 布鲁克海文国家实验室第二代同步辐射光源）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对超导铌薄膜表面氧化物导致的两能级系统介电损耗问题，提出通过热退火形成Nb-Pt合金层抑制氧化的方法，实验和理论验证了其稳定性和有效性。
AI 中文摘要
由表面和界面上的两能级系统（TLS）引起的介电损耗仍然是超导transmon量子比特相干性的主要限制因素。铌（Nb）是超导量子电路中广泛使用的材料，在环境条件下容易形成原生氧化物，导致有损介电界面，从而降低器件性能。本文展示了一种稳健且可扩展的制造策略，用于化学稳定Nb表面并抑制进一步氧化，包括保护表面和侧壁区域。制备了具有类体超导转变温度（$T_c = 9.30\pm0.10$ K）的高纯Nb薄膜。我们证明，在原生氧化物形成后沉积的薄Pt封装层，可以通过热退火在表面转变为Nb-Pt合金。光谱和显微分析证实了化学稳定的金属合金层的形成及其抑制进一步氧化物生长的能力。从头算模拟阐明了与Pt掺入原生氧化铌相关的原子尺度重排和电子结构演化，为合金化表面的稳定机制提供了见解。该方法为工程化化学稳健的Nb界面（包括侧壁）提供了一条材料途径，以实现更高相干性的超导量子比特架构。
英文摘要
Dielectric losses at surfaces and interfaces remains a primary limitation to coherence in superconducting transmon qubits. Niobium (Nb), a widely used material in superconducting quantum circuits, readily forms native oxides under ambient conditions, leading to lossy dielectric interfaces that degrade device performance. Here, we demonstrate a novel fabrication strategy that chemically transforms the native dielectric oxide on Nb into a metallic Pt--Nb surface alloy through post-oxidation Pt deposition followed by thermal annealing, thereby stabilizing Nb surfaces against further oxidation, potentially including sidewall regions. High-purity Nb films were fabricated with bulk-like superconducting transition temperatures ($T_c = 9.30\pm0.10$~K). Spectroscopic and microscopic analyses confirm the conversion of the native oxide into a chemically stable, metallic alloy-dominated layer that suppresses subsequent oxide growth. Ab initio simulations elucidate the atomic-scale rearrangement and electronic structure evolution associated with Pt incorporation into native niobium oxide, providing insight into the mechanism underlying the oxide-to-metal transformation and stabilization of the alloyed surface.
Comments49 pages, 18 figures
