Hybrid superconductor/semiconductor qubits are a key part of QCoR’s portfolio, offering capabilities beyond conventional superconducting circuits through voltage-tunable superconductivity and new routes to noise protection. A central enabling platform for this work is our Ge quantum wells grown in-house by molecular beam epitaxy, which serve as the primary material system for developing and studying next-generation hybrid devices.

Device fabrication and characterization: We fabricate gatemon qubits and related hybrid super-semi devices to explore the fundamental physics and performance of superconductor–semiconductor systems. This includes fabricating Josephson junctions to study proximity effects, as well as gatemon circuits that realize gate-tunability in a transmon-like architecture while reducing losses through the use of silicon substrates.

Anharmonic and parity-protected modalities: We explore hybrid architectures aimed at boosting anharmonicity and enabling charge-parity protection, including SQUID-based systems built on Ge quantum wells on Si substrates. These efforts target low-loss operation and enhanced qubit robustness through engineered super-semi coupling.

Fraunhofer qubits: Our team investigates qubits based on Fraunhofer interference in Josephson junctions under applied magnetic fields, using them to probe Andreev bound-state dynamics in a qubit form factor at GHz frequencies, providing a powerful spectroscopy platform for hybrid superconducting systems.