Ultrahigh vacuum packaging and surface cleaning for quantum devices

Abstract

We describe design, implementation, and performance of an ultra-high vacuum (UHV) package for superconducting qubit chips or other surface sensitive quantum devices. The UHV loading procedure allows for annealing, ultra-violet light irradiation, ion milling, and surface passivation of quantum devices before sealing them into a measurement package. The package retains vacuum during the transfer to cryogenic temperatures by active pumping with a titanium getter layer. We characterize the treatment capabilities of the system and present measurements of flux tunable qubits with an average T1 = 84 μs and T2echo=134 μs after vacuum-loading these samples into a bottom loading dilution refrigerator in the UHV-package.