Electrodynamics of tunnel ferromagnetic Josephson junctions: dissipation mechanisms and study of noise fluctuations

Ferromagnetic Josephson junctions are the object of an intense research activity focused on the study of the competition between superconductivity and ferromagnetism, as well as the fundamental cell of ground-breaking tunable devices in the field of superconducting spintronics. A unique class of SFS JJs is that of tunnel ferromagnetic junctions, in which the barrier is an insulating ferromagnet or a multi-layered barrier composed of an insulator matched with a ferromagnet. These devices combine the typical low-dissipative behavior of tunnel JJs and the hysteretic magnetization of the barrier, which gives the possibility to implement them in classical and quantum circuits that require high-coherence and low-dissipation. We propose a feasibility study of a novel hybrid transmon circuit that incorporates a tunnel SFS JJ. The aim is to offer an alternative scheme for the addressing of the qubit frequency based on the use of pulsed magnetic fields to reduce the flux-bias noise. Here we report a comprehensive study of the dissipation mechanisms in such devices, focusing on both the electrodynamics and circuits parameters and their scaling energies, as well as the impact of critical current and magnetic fluctuations on the coherence of the whole system.