Krypton sputtering unlocks low-temperature Ta films for scalable quantum devices

Researchers show krypton gas in magnetron sputtering enables cubic bcc tantalum films on silicon at around 200°C, broadening the fabrication window for quantum hardware. These krypton-sputtered Ta films deliver low microwave losses in resonators, while higher-temperature Ta films suffer from Ta–Si intermixing and higher losses. Notably, transmon qubits fabricated with these films achieved a compact 20‑μm capacitor gap and quality factors up to 16.9 million, indicating a scalable route to high-performance superconducting quantum devices.