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Superconductor Science and Technology

Benchmarking reproducible low-loss wire-bond interconnects for superconducting quantum computing

Zilin Wang, Zihao Zhang, Yuzhe Xiong, Jingjing Niu, Jiawei Qiu, Dapeng Yu

Published Sep 1, 2026• 0 citations
Publisher

Abstract

Abstract Reproducible low-loss microwave interconnects are essential for scaling modular superconducting quantum processors and networks. Wire bonds provide a simple and flexible route to galvanic connections in such systems, but their microwave loss and reproducibility at millikelvin temperatures remain insufficiently quantified. Here we demonstrate reproducible low-loss aluminum wire-bond interconnects in both superconducting cable resonators and planar tantalum resonators. In the cable devices, a wire-bond connection is placed at the midpoint of a high-quality resonator, where the different current distributions of odd and even modes separate connection-induced loss from intrinsic cable dissipation within the same device. Across devices fabricated with different bond numbers and ultrasonic powers, a stable bonding window yields no resolvable connection resistance above the practical resolution of order 0.1 m Ω . Measurements of planar resonators on two chips independently show no systematic degradation of the internal quality factor from wire-bond ground terminations within the device-to-device variation. These results establish aluminum wire bonding as a reproducible low-loss interconnect for superconducting microwave circuits, supporting the scalable assembly of modular superconducting quantum processors and networks.

DOI
10.1088/1361-6668/aea308

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Low-loss cavities are important in building high-coherence superconducting quantum computers. Generating high-quality joints between parts is crucial for the realization of a scalable quantum computer using the circuit quantum electrodynamics (cQED) framework. In this paper, we adapt the technique of indium bump bonding to cQED to realize high-quality superconducting microwave joints between chips. We use this technique to fabricate compact superconducting cavities in the multilayer microwave integrated quantum circuit (MMIQC) architecture and achieve single photon quality factors over 300 × 106 or single-photon lifetimes approaching 5 ms. To quantify the performance of the resulting seam, we fabricate microwave stripline resonators in multiple sections connected by different numbers of bonds, resulting in a wide range of seam admittances. The measured quality factors combined with the designed seam admittances allow us to bound the conductance of the seam at gseam≥2×1010/(Ω m). Such a conductance should enable the construction of micromachined superconducting cavities with a quality factor of at least a billion. These results demonstrate the capability to construct very high-quality microwave structures within the MMIQC architecture.
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