SQMS Nanofabrication Taskforce: Towards Fabrication of High Coherence Superconducting Qubits
SQMS Nanofabrication Taskforce, which brings together experts in nanofabrication and materials science at the SQMS Center, has been launched to implement novel materials, substrates, and fabrication techniques for high coherence superconducting quantum devices. In a first coordinated effort, the Nanofabrication Taskforce developed fabrication processes to eliminate the lossy materials at surfaces and interfaces of superconducting qubits to enhance qubit coherence. The initial results of this study demonstrated T1 enhancement by almost an order of magnitude with best T1 s reaching ~ 600 $\mu$s. [1] We attribute this improvement to the replacement of lossy native Nb oxide layer with native Ta oxide, which is thinner and less disordered. we are now currently working on strategies with an aim towards moving qubit coherence times to millisecond timescales and beyond. The results of a systematic study will be presented to address substrate preparation, alternative materials as low loss platforms (Nb, Ta, and Re), novel non-oxide forming low loss capping layers such as proximitized Au, optimized qubit designs, and optimized Josephson junction materials, processing, and design.