Lozano D P, Mongillo Massimo, Raes Bart, Canvel Yann, Massar Shana, Vadiraj A M, Ivanov Tsvetan, Acharya Rohith, Damme Jacques Van, de Vondel Joris Van, Wan Danny, Potočnik Anton, Greve K De
Imec, Kapeldreef 75, Leuven, B-3001, Belgium.
Department of Electrical Engineering (ESAT), KU Leuven, Leuven, B-3001, Belgium.
Adv Sci (Weinh). 2025 Oct;12(39):e09244. doi: 10.1002/advs.202509244. Epub 2025 Aug 11.
α-Tantalum (α-Ta) is an emerging material for superconducting qubit fabrication due to the low microwave loss of its stable native oxide. However, hydrogen absorption during fabrication, particularly when removing the native oxide, can degrade performance by increasing microwave loss. This work demonstrates that hydrogen can enter α-Ta thin films when exposed to 10 vol% hydrofluoric acid for 3 min or longer, leading to an increase in power-independent ohmic loss in high-Q resonators at millikelvin temperatures. It is further shown that annealing at 500 °C in ultra-high vacuum (10 Torr) for 1 h fully removes hydrogen and restores the resonators' intrinsic quality factors to ≈4 million at the single-photon level. These findings identify a previously unreported loss mechanism in α-Ta and offer a pathway to reverse hydrogen-induced degradation in quantum devices based on α-Ta and, by extension also Nb, enabling more robust fabrication processes for superconducting qubits.
α-钽（α-Ta）因其稳定的原生氧化物具有低微波损耗，是一种用于制造超导量子比特的新兴材料。然而，在制造过程中吸收氢，特别是在去除原生氧化物时，会因增加微波损耗而降低性能。这项工作表明，当暴露于10体积%的氢氟酸中3分钟或更长时间时，氢会进入α-Ta薄膜，导致毫开尔文温度下高Q谐振器中与功率无关的欧姆损耗增加。进一步表明，在超高真空（10托）中于500°C退火1小时可完全去除氢，并将谐振器在单光子水平的本征品质因数恢复到约400万。这些发现确定了α-Ta中一种以前未报道的损耗机制，并提供了一条途径来逆转基于α-Ta以及由此延伸的铌的量子器件中氢诱导的降解，从而实现更稳健的超导量子比特制造工艺。
