Towards Design and Fabrication of Transmons using Single-Crystal Silicon Fins

While the invention of the transmon has fueled rapid developments in the quantum information systems field, decoherence sources inherent in the materials and scaling challenges remain limitations as the field moves to larger scale quantum processing units. Improvements in materials growth and device processing have driven improvements to transmon coherence, though little has changed in ways of the transmon designs which typically consist of a planar superconducting capacitor shunted by an aluminum/aluminum-oxide/aluminum Josephson junction. In this work, we incorporate high aspect ratio fins fabricated from low-loss, single-crystal silicon in superconducting circuits to enhance transmon coherence and scalability. Loss measurements performed on lumped element resonators fabricated using parallel plate capacitors made from silicon fins show significant improvement over conventional interdigitated capacitor designs. Efforts to incorporate aluminum-contacted silicon fins as capacitors in transmon designs will be discussed as well as efforts to thin the silicon fins to the tunneling limit to realize merged element transmons using silicon fins.