Mitigating coherent loss in superconducting circuits using molecular self-assembled monolayers

Mohammed Alghadeer; Archan Banerjee; Kyunghoon Lee; Hussein Hussein; Hossein Fariborzi; Saleem Rao

doi:10.1038/s41598-024-77227-7

Mitigating coherent loss in superconducting circuits using molecular self-assembled monolayers

Sci Rep. 2024 Nov 9;14(1):27340. doi: 10.1038/s41598-024-77227-7.

Authors

Mohammed Alghadeer^{1

2

3}, Archan Banerjee^{4

5}, Kyunghoon Lee^{4

5}, Hussein Hussein^{6

7}, Hossein Fariborzi⁶, Saleem Rao⁸

Affiliations

¹ Department of Physics, University of California, Berkeley, CA, 94720, USA. [email protected].
² Applied Mathematics and Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. [email protected].
³ Department of Physics, Clarendon Laboratory, University of Oxford, Oxford, OX1 3PU, UK. [email protected].
⁴ Department of Physics, University of California, Berkeley, CA, 94720, USA.
⁵ Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
⁶ CEMSE Division, King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia.
⁷ Department of Mechanical Engineering, MSFEA, American University of Beirut, Beirut, 1107 2020, Lebanon.
⁸ Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran, 31261, Saudi Arabia. [email protected].

Abstract

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.