Tantalum microwave resonators with ultra-high intrinsic quality factors
Lili Shi, Tingting Guo, Runfeng Su, Tianyuan Chi, Yifan Sheng, Junliang Jiang, Chunhai Cao, Jingbo Wu, Xuecou Tu, Guozhu Sun, Jian Chen, Peiheng Wu
Abstract
We acquire tantalum thin film in its α phase (α-Ta) using direct-current magnetron sputtering. According to x-ray diffraction results, 110-Ta is dominant. Quarter-wavelength coplanar waveguide resonators are fabricated with the α-Ta film and characterized at millikelvin in a dilution refrigerator. In the single photon regime, an intrinsic quality factor (Qi) up to 3×106 is obtained in these resonators. At high power, Qi rises to 6×106. Moreover, we also fabricate an array with 7 × 7 lumped element resonators using the α-Ta film. The array shows excellent uniformity. At high power, Qis of all pixels exceed 1×106. In the single photon regime, Qis of over 90% pixels exceed 1×106. Superconducting quantum computing and ultrasensitive electromagnetic wave detectors will benefit a lot from devices based on the α-Ta film.