Adam Schwartzberg, Shaul Aloni, Sinéad Griffin, Yashwanth Balaji, Mythili Surendran, Lawrence Berkeley National Laboratory, Berkeley, CA
Superconducting quantum devices rely on radio frequency resonant cavities, often at the single photon level. Preserving coherence, for tangible applications, requires the fabrication of cavities with quality factors that are as high as possible. Similar to optical cavities, fabrication quality plays an important role. However, the addition of quantum device elements (e.g. Josephson Junctions) and additional loss channels present at the operational frequency (two level systems) add complex interactions that play an enormous role in achieving the required performance. To a great extent, these challenges are related to specific materials questions that are currently poorly understood for devices of this type. Research into this area is difficult due to the diversity of expertise and instrumentation needed. Materials growth, fabrication, milli-Kelvin cryogenics, and radio frequency electronics and measurement are the basic building blocks needed to understand the operational effects of materials and device fabrication choices. To this end, we at the Molecular Foundry have been building a holistic toolset for answering these questions. In this talk I will present progress on our work developing these facilities starting with our previous work to understand materials interfaces in quantum devices as a motivation, followed by the development and implementation of a new robotically controlled cluster deposition and analysis tool, and finally our progress in building our own cryogenic characterization suite. The cluster deposition tool contains four deposition stations (e-beam evaporation, reactive sputtering, and oxide and nitride atomic layer deposition), a multi-sample load-lock and glovebox, and an analytical chamber for in-vacuo characterization (XPS, FTIR, and ellipsometry) which allow us to grow a wide range of materials with clean interfaces and the ability to understand the nature of those interfaces. We combine these new growth capabilities with advanced materials characterization and nanofabrication expertise to explore the many facets of this open question. Additionally, I will discuss AI/ML techniques which we are developing to be implemented autonomously with the cluster tool and will provide new pathways for solving complex materials challenges.