Circuit quantum electrodynamics, where photons are coherently coupled to artificial atoms built with superconducting circuits, has enabled the investigation and control of macroscopic quantum-mechanical phenomena in superconductors. Recently, hybrid circuits incorporating semiconducting nanowires and other electrostatically-gateable elements have provided new insights into mesoscopic superconductivity. Extending the capabilities of hybrid flux-based circuits to work in magnetic fields would be especially useful both as a probe of spin-polarized Andreev bound states and as a possible platform for topological qubits. The fluxonium is particularly suitable as a readout circuit for topological qubits due to its unique persistent-current based eigenstates. In this Letter, we present a magnetic-field compatible hybrid fluxonium with an electrostatically-tuned semiconducting nanowire as its non-linear element. We operate the fluxonium in magnetic fields up to 1T and use it to observe the φ0-Josephson effect. This combination of gate-tunability and field-compatibility opens avenues for the exploration and control of spin-polarized phenomena using superconducting circuits and enables the use of the fluxonium as a readout device for topological qubits.
@article{arxiv.1910.07978,
title = {A gate-tunable, field-compatible fluxonium},
author = {Marta Pita-Vidal and Arno Bargerbos and Chung-Kai Yang and David J. van Woerkom and Wolfgang Pfaff and Nadia Haider and Peter Krogstrup and Leo P. Kouwenhoven and Gijs de Lange and Angela Kou},
journal= {arXiv preprint arXiv:1910.07978},
year = {2021}
}