Flux tuning of qubit frequencies in superconducting quantum processors is fundamental for implementing single and multi-qubit gates in quantum algorithms. Typical architectures involve the use of DC or fast RF lines. However, these lines introduce significant heat dissipation and undesirable decoherence mechanisms, leading to a severe bottleneck for scalability. Among different solutions to overcome this issue, we propose integrating tunnel Superconductor-Insulating-thin superconducting interlayer-Ferromagnet-Superconductor Josephson junctions (SIsFS JJs) into a novel transmon qubit design, the so-called ferrotransmon. SIsFS JJs provide memory properties due to the presence of ferromagnetic barriers and preserve at the same time the low-dissipative behavior of tunnel-insulating JJs, thus promoting an alternative tuning of the qubit frequency. In this work, we discuss the fundamental steps towards the implementation of this hybrid ferromagnetic transmon. We will give a special focus on the design, simulations, and preliminary experimental characterization of superconducting lines to provide in-plane magnetic fields, fundamental for an on-chip control of the qubit frequencies in the ferrotransmon.
@article{arxiv.2412.06562,
title = {Towards novel tunability schemes for hybrid ferromagnetic transmon qubits},
author = {Halima Giovanna Ahmad and Raffaella Ferraiuolo and Giuseppe Serpico and Roberta Satariano and Anna Levochkina and Antonio Vettoliere and Carmine Granata and Domenico Montemurro and Martina Esposito and Giovanni Ausanio and Loredana Parlato and Giovanni Piero Pepe and Alessandro Bruno and Francesco Tafuri and Davide Massarotti},
journal= {arXiv preprint arXiv:2412.06562},
year = {2024}
}