Gate-Tunable Field-Compatible Fluxonium
Marta Pita‐Vidal, Arno Bargerbos, Chung-Kai Yang, David J. van Woerkom, Wolfgang Pfaff, Nadia Haider, Peter Krogstrup, Leo P. Kouwenhoven, G. de Lange, Angela Kou
Abstract
Hybrid superconducting circuits have been used to investigate mesoscopic superconductivity, but mostly just at low magnetic fields, as typical Al-based circuits are incompatible with magnetic fields, and superconducting circuits are sensitive to external magnetic flux noise. To overcome these challenges, the authors build a hybrid fluxonium system composed of (Nb,Ti)N, with a gradiometric design. They observe the spectrum of the hybrid fluxonium in fields of up to 1T, and probe the ${\ensuremath{\phi}}_{0}$ Josephson effect. These results enable future exploration of topological superconductivity, as well as readout of long-lifetime spin-polarized qubits using superconducting circuitry.