New SubmissionSimulating Interface Dielectric Loss in Superconducting Coplanar-Waveguide Resonators

Superconducting quantum computing architectures rely on coplanar-waveguide (CPW) resonators and qubits, both of which are susceptible to energy loss arising from two-level systems (TLS) within bulk and interfacial dielectrics. CPW resonators, in particular, serve as valuable standalone platforms for investigating material losses in the single quantum excitation regime of planar superconducting quantum circuits. Recent experimental studies have demonstrated a reduction in TLS losses through the modification of the air-interface with less lossy materials. This work presents a simulation-based study of TLS losses in CPW resonators, focusing on the measurement of resonator quality factors. The simulations involve modifying various interfaces with additional low-loss materials and employing etching techniques, mirroring recent experimental approaches. Our results indicate a significant improvement in quality factor when air-interfaces are modified with low-loss materials or through etching, aligning with recent experimental observations [1, 2]. These findings provide strong support for the experimental conclusions regarding the impact of air-interface modifications on TLS losses. The simulation methodology employed in this study can serve as a valuable tool for guiding targeted improvements in resonator design and fabrication processes, ultimately contributing to the advancement of superconducting quantum computing.

1. M. V. P. Altoé, A. Banerjee, C. Berk, A. Hajr, A. Schwartzberg, C. Song, M. Alghadeer, S. Aloni, M. J. Elowson, J. M. Kreikebaum, Ed K. Wong, S. M. Griffin, S. Rao, A. Weber-Bargioni, A. M. Minor, D. I. Santiago, S. Cabrini, I. Siddiqi, D. F. Ogletree, Localization and mitigation of loss in niobium superconducting circuits. PRX Quantum 3, 020312 (2022).

M. Alghadeer, A. Banerjee, A. Hajr, H. Hussein, H. Fariborzi, S. G. Rao, Surface Passivation of Niobium Superconducting Quantum Circuits Using Self-Assembled Monolayers, ACS Applied Materials & Interfaces 15 (1), 2319-2328 (2023).