Sandia National Laboratories Integrates Superconducting Circuits with AlScN Phonons

Researchers from Sandia National Laboratories, the University of Colorado Boulder, University of Arizona, and University of Pennsylvania are pursuing a monolithic platform, aiming to build a single unified structure rather than simply connecting separate components. This approach seeks to overcome limitations in current quantum information processing by leveraging the potential for ultra-compact designs, low losses, and increased connectivity offered by phonons. The work proposes and characterizes a platform combining aluminum superconducting circuits on silicon carbide with piezoelectric AlScN on silicon carbide, enabled by removing AlScN to fabricate microwave resonators directly on the substrate while preserving regions for phonon transduction. This approach isn’t simply connecting existing circuits; it’s building a unified structure where superconducting and acoustic elements coexist on the same chip. The core innovation lies in the selective removal of AlScN, creating exposed regions of SiC ideal for fabricating aluminum superconducting microwave resonators. This allows for direct deposition without compromising the performance of either component. The resulting aluminum-on-SiC resonators exhibited a coherent lifetime of 2.9 seconds, confirming the compatibility of exposed SiC with superconducting quantum devices, a critical step for scalability. Complementing this, cryogenic surface acoustic delay-line measurements on the retained AlScN-on-SiC regions revealed low phononic propagation loss at 4.05 GHz, translating to an estimated phonon lifetime of 7.6 seconds. This low loss is particularly noteworthy given the challenges of maintaining coherence in piezoelectric materials. The researchers also highlight a previously demonstrated electromechanical coupling coefficient of approximately 4.3, with a theoretical upper bound of 8 in this frequency range, further solidifying the platform’s promise.

Superconducting Resonator Coherence on Exposed Silicon Carbide Researchers are increasingly focused on integrating superconducting circuits with acoustic phonons to advance quantum technologies, yet maintaining both high coherence and scalability remains a significant hurdle. Current approaches often rely on bonding separate materials or utilizing thin films with inherent limitations in piezoelectric coupling or fabrication complexity. This design aims to overcome the challenges of existing hybrid systems by creating a unified structure rather than simply connecting disparate components. The core of this innovation lies in a fabrication process that allows for the creation of resonators exhibiting a coherent lifetime of 2.9 seconds. The choice of 4H-SiC as the substrate is deliberate; it’s known for its potential to support high-frequency performance and minimize signal loss, crucial for maintaining quantum coherence. Cryogenic surface acoustic delay-line measurements reveal an estimated phonon lifetime of 7.6 seconds, indicating the potential for long-lived acoustic wave propagation. The combination of these factors positions Al-on-SiC/AlScN-on-SiC as a promising material system for realizing integrated superconducting-phononic quantum systems, potentially enabling advancements in quantum acoustic networking and hybrid quantum architectures.

The team’s work establishes a pathway toward miniaturization and improved efficiency in quantum information processing. Researchers from the University of Colorado Boulder, Sandia National Laboratories, University of Arizona, and University of Pennsylvania are developing a novel approach to hybrid quantum systems, moving beyond simply connecting superconducting circuits and acoustic phonons to envisioning a monolithic integration. While conventional methods often rely on bonding separate components, the team aims to fabricate the entire system within a single structure, promising increased miniaturization and efficiency. This architecture is enabled by the selective removal of AlScN from designated regions of the chip, allowing aluminum superconducting microwave resonators to be fabricated directly on the SiC while preserving adjacent AlScN-on-SiC regions for phonon transduction. Crucially, the resulting devices demonstrate compatibility between these disparate elements. Aluminum resonators fabricated on the exposed SiC exhibited a coherent lifetime of 2.9 seconds, a key metric indicating the stability of quantum information. These findings build upon previously established electromechanical coupling of approximately 4.3. A new material pairing is demonstrating coherence in both superconducting circuits and acoustic phonons. This approach tackles a key hurdle in quantum acoustics: achieving both strong coupling between electrical and mechanical vibrations without sacrificing the performance of delicate superconducting components. In parallel, cryogenic surface acoustic delay-line measurements on the retained AlScN-on-SiC regions possess low phononic propagation loss at 4.05 GHz, corresponding to an estimated phonon lifetime of 7.6 seconds. Together with the previously demonstrated electromechanical coupling coefficient of approximately 4.3 and a theoretical upper bound of 8 in this frequency range, these results establish Al-on-SiC/AlScN-on-SiC as a promising monolithic platform for integrating superconducting microwave circuits with piezoelectric phononic components for quantum acoustic networking and hybrid quantum systems. Source: https://arxiv.org/abs/2607.14319 Stay currentSee today’s quantum computing news on Quantum Zeitgeist for the latest breakthroughs in qubits, hardware, algorithms, and industry deals. Tags: