Alghadeer Mohammed, Banerjee Archan, Lee Kyunghoon, Hussein Hussein, Fariborzi Hossein, Rao Saleem
Department of Physics, University of California, Berkeley, CA, 94720, USA.
Applied Mathematics and Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
Sci Rep. 2024 Nov 9;14(1):27340. doi: 10.1038/s41598-024-77227-7.
In planar superconducting circuits, decoherence due to materials imperfections, especially two-level-system (TLS) defects at different interfaces, is a primary hurdle for advancing quantum computing and sensing applications. Traditional methods for mitigating TLS loss, such as etching oxide layers at metal and substrate interfaces, have proven to be inadequate due to the persistent challenge of oxide regrowth. In this work, we introduce a novel approach that employs molecular self-assembled monolayers (SAMs) to chemically bind at different interfaces of superconducting circuits. This technique is specifically tested here on coplanar waveguide (CPW) resonators, in which this method not only impedes oxide regrowth after surface etching but can also tailors the dielectric properties at different resonators interfaces. The deployment of SAMs results in a consistent improvement in the measured quality factors across multiple resonators, surpassing those with only oxide-etched resonators. The efficiency of our approach i3s supported by microwave measurements of multiple devices conducted at millikelvin temperatures and correlated with detailed X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) characterizations of SAM-passivated resonators. The compatibility of SAMs materials with the established fabrication techniques offers a promising route to improve the performance of superconducting quantum devices.
在平面超导电路中，由于材料缺陷，特别是不同界面处的两能级系统（TLS）缺陷导致的退相干，是推进量子计算和传感应用的主要障碍。传统的减轻TLS损耗的方法，如蚀刻金属与衬底界面处的氧化层，由于氧化层再生的持续挑战，已被证明是不够的。在这项工作中，我们引入了一种新颖的方法，该方法采用分子自组装单分子层（SAMs）在超导电路的不同界面进行化学结合。此技术在此处针对共面波导（CPW）谐振器进行了专门测试，在该谐振器中，此方法不仅能阻止表面蚀刻后的氧化层再生，还能调整不同谐振器界面处的介电特性。SAMs的应用使得多个谐振器的测量品质因数得到持续改善，超过了仅经过氧化蚀刻的谐振器。我们方法的有效性得到了在毫开尔文温度下对多个器件进行的微波测量的支持，并与SAMs钝化谐振器的详细X射线光电子能谱（XPS）和透射电子显微镜（TEM）表征相关联。SAMs材料与既定制造技术的兼容性为提高超导量子器件的性能提供了一条有前景的途径。
