AI 中文总结
该研究开发了采用电镀铟凸点键合的三维传输子倒装片集成架构，证明其与高相干超导电路兼容，为三维混合量子集成建立了有前景的平台。
AI 中文摘要
倒装片集成为可扩展超导量子处理器及混合半导体-超导体量子器件提供了极具前景的途径。我们开发了一种采用电镀铟的三维传输子（transmon）架构，其中量子比特的电场几乎均等分布在两个经凸点键合的衬底之间，同时保持铟凸点界面处的参与度较低。该几何结构非常适合未来的混合量子比特，能够集成不同的材料平台，同时将对凸点界面损耗的敏感性降至最低。利用该平台，我们评估了用于超导量子电路的电镀铟互连。集成电镀铟凸点的倒装片传输子表现出约10^6的量子比特品质因数。此外，我们对共面波导谐振器进行了系统研究，以确定与电镀工艺相关的损耗。特别地，我们发现与金层相关的表面损耗可能是量子比特衰减率的主要贡献因素，该金层用于实现与铟的良好电接触。这些结果证明了电镀铟技术与高相干超导电路的兼容性，并为三维混合量子集成建立了一个极具前景的平台。
英文摘要
Flip-chip integration offers a promising route toward scalable superconducting quantum processors and hybrid semiconductor-superconductor quantum devices. We develop a three-dimensional transmon architecture using electroplated indium in which the qubit electric field is shared nearly equally between two bump-bonded substrates while maintaining low participation at the indium-bump interface. The resulting geometry is well suited for future hybrid qubits, enabling the integration of distinct material platforms while minimizing sensitivity to bump-interface loss. Using this platform, we evaluate electroplated indium interconnects for superconducting quantum circuits. Flip-chip transmons incorporating electroplated indium bumps exhibit qubit quality factors around $10^6$. In addition, a systematic study of coplanar-waveguide resonators is used to identify losses associated with the electroplating process. In particular, we find that surface losses associated with the gold-layer, used to enable good electric contact with the indium, is likely the primary contributor to the qubit decay rate. These results demonstrate the compatibility of electroplated indium technology with high-coherence superconducting circuits and establish a promising platform for three-dimensional hybrid quantum integration.
Comments11 pages, 8 figures
