Engineering microwave resonators with a finite cubic nonlinearity while suppressing unwanted Kerr effects remains a recurring challenge in quantum information processing.

To address this, Vittorio Buccheri and Prof. Simone Gasparinetti from 202Q-lab, together with additional researchers from Chalmers University of Technology, have published a preprint describing how to control these dynamics in a semiconductor–superconductor hybrid device.

By studying superconducting resonators hosting Al-InAs weak links, we show that the Kerr nonlinearity can be tuned through zero using either magnetic flux or gate voltage.

We also report the first experimental observation of a nonzero cubic nonlinearity in a semiconductor–superconductor hybrid device and demonstrate three-wave mixing and parametric amplification. Importantly, we find that a sizable cubic nonlinearity can be maintained while tuning the Kerr nonlinearity through zero.

The observed behavior is qualitatively captured by an effective model based on Andreev bound states.

Our work establishes semiconducting Josephson junctions as a versatile architecture for tunable nonlinear superconducting circuits, with potential applications in parametric amplification and engineered bosonic-mode interactions.

Preprint link: https://arxiv.org/abs/2608.28428