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High-quality and field resilient microwave resonators on Ge quantum well heterostructures
Fig. 1: High-quality coplanar waveguide resonators (High-Q CPW) on germanium quantum wells (Ge QW) (a) Cross-sectional schematic (not to scale) of a microwave CPW patterned from an Al film deposited on a Ge/SiGe quantum well, which is epitaxially grown on a Ge substrate. (b–d) Fit (orange solid line) of the I/Q, transmission amplitude and phase response, respectively. The extracted quality factor exceeds 4.8 × 104 at an average circulating photon number of < np > ≃ 1.0. Publication: Ruggiero, L., Ciaccia, C., Drexler, P. et al. npj Quantum Inf 12, 118 (2026).
Researchers in the group of BQC Prof. Andrea Hofmann realized high-quality, magnetic-field-resilient microwave resonators on germanium quantum well heterostructures.
Superconducting resonators integrated with germanium quantum wells offer a promising platform for hybrid quantum devices. Yet, the most common heterostructure architectures have so far been limited by sizable photon losses.
BQC Prof. Andrea Hofmann and her research group have developed high-quality, magnetic-field-resilient microwave resonators on germanium quantum well heterostructures.
Their resonators yield photon lifetimes exceeding the coherence time of most Ge spin qubits and remain operational in magnetic fields similar to those used for spin qubit experiments.
Andrea Hofmann: “With this work, we address a major challenge on the road to Ge-based quantum information processing: the realization of on-chip, low-loss microwave resonators."