AI 中文总结
研究超导电路材料损耗问题，通过铝微结构工程及介质微调，包括沉积加热与两步蚀刻技术，减轻两种损耗机制，使铝谐振器品质因数大幅提升，为超导量子器件性能提升提供途径。
AI 中文摘要
超导电路中的材料损耗从根本上限制了量子比特的相干时间和谐振器的品质因数。多数研究致力于减轻电路界面处的损耗。然而，TLS与非TLS损耗与超导金属固有特性和介质边缘平滑度之间的关联尚未得到充分研究。本工作将铝膜晶粒尺寸与非TLS损耗、介质微调轮廓及粗糙度与TLS损耗相联系，并减轻了这两种损耗机制。通过沉积时加热来设计铝微结构以减少金属相关损耗，还引入两步蚀刻技术抑制介质TLS损耗。结果展示了低损耗铝谐振器的制造途径，品质因数提高了两个数量级，这能提升超导量子器件性能。
英文摘要
Material losses in superconducting circuits fundamentally limit qubit coherence times and resonator quality factors. Most research efforts focus on mitigating losses at circuit interfaces, including metal--substrate, substrate--air, and metal--air interfaces. However, the correlation between TLS and non-TLS losses with the intrinsic properties of the superconducting metal and the dielectric edge smoothness is not well studied. In this work, we link the aluminum film grain size to non-TLS losses and the dielectric trimming profile and roughness to TLS loss; both loss mechanisms are subsequently mitigated. To reduce metal-related losses, we engineer the aluminum microstructure by heating during deposition, increasing grain size and reducing grain boundary density. Beyond mitigating metal losses, we introduce a two-step etching technique, Tropic etching, to suppress dielectric TLS loss by producing an ultra-smooth silicon surface with minimal defects and redeposition. These results lay out the fabrication pathway for aluminum resonators with lower loss, demonstrating two-orders-of-magnitude improvement in quality factor from $6\times10^{4}$ to $2.3\times10^{6}$. Since aluminum is the basis for most high-coherence Josephson junctions and dielectric edges are inherent to all common device geometries, the improvements in aluminum microstructure and edge profiling, presented here, can enhance the performance of superconducting quantum devices.
