Minimizing Kinetic Inductance in Tantalum-Based Superconducting Coplanar Waveguide Resonators for Alleviating Frequency Fluctuation Issues

TL;DR

This paper presents methods to significantly reduce frequency fluctuations in tantalum-based superconducting coplanar waveguide resonators, enabling more precise quantum device fabrication while maintaining high quality factors.

Contribution

It introduces fabrication and design strategies that decrease frequency variance by over 100 times in tantalum resonators, addressing a key challenge in quantum device consistency.

Findings

Frequency fluctuation reduced by over 100 times

High internal quality factor maintained

Enhanced potential for large-scale quantum chips

Abstract

Advancements in the fabrication of superconducting quantum devices have highlighted tantalum as a promising material, owing to its low surface oxidation microwave loss at low temperatures. However, tantalum films exhibit significantly larger kinetic inductances compared to materials such as aluminum or niobium. Given the inevitable variations in film thickness, this increased kinetic inductance leads to considerable, uncontrolled frequency variances and shifts in components like superconducting coplanar waveguide (SCPW) resonators. Achieving high precision in resonator frequencies is crucial, particularly when multiple resonators share a common Purcell filter with limited bandwidth in superconducting quantum information processors. Here, we tackle this challenge from both fabrication and design perspectives, achieving a reduction in resonator frequency fluctuation by a factor of more than 100. Concurrently, the internal quality factor of the SCPW resonator remains at high level. Our findings open up new avenues for the enhanced utilization of tantalum in large-scale superconducting chips.