Fabrication of superconducting qubits using free-standing mineral masks*

Over the last years there has been a significant improvement on the energy relaxation properties of superconducting qubits. State-of-the-art transmon and fluxonium qubits exhibit energy relaxation times in the order of hundreds of microseconds and few milliseconds respectively. Progress in their design has resulted in minimizing losses coming from the dielectric environment and radiation into the electromagnetic environment, in addition to gains due to better understanding and control of their inductive losses. However, advancements on reducing dielectric losses associated with organic residues produced by traditional fabrication techniques have been modest. In this talk, we will propose a new fabrication technology for planar superconducting circuits that replaces the commonly used resist-based lithography masks with free-standing mineral masks. Furthermore, we will present preliminary results on the energy relaxation properties and reproducibility of transmon qubits that are fabricated using this new method.