Procolo Lucignano

A hybrid ferromagnetic transmon qubit: circuit design, feasibility and detection protocols for magnetic fluctuations

  1. Halima Giovanna Ahmad,
  2. Valentina Brosco,
  3. Alessandro Miano,
  4. Luigi Di Palma,
  5. Marco Arzeo,
  6. Domenico Montemurro,
  7. Procolo Lucignano,
  8. Giovanni Piero Pepe,
  9. Francesco Tafuri,
  10. Rosario Fazio,
  11. and Davide Massarotti
We propose to exploit currently available tunnel ferromagnetic Josephson junctions to realize a hybrid superconducting qubit. We show that the characteristic hysteretic behavior of
the ferromagnetic barrier provides an alternative and intrinsically digital tuning of the qubit frequency by means of magnetic field pulses. To illustrate functionalities and limitation of the device, we discuss the coupling to a read-out resonator and the effect of magnetic fluctuations. The possibility to use the qubit as a noise detector and its relevance to investigate the subtle interplay of magnetism and superconductivity is envisaged.
arxiv pdf

Realization of 0 – π states in SFIS Josephson junctions. The role of spin-orbit interaction and lattice impurities

  1. Martina Minutillo,
  2. Roberto Capecelatro,
  3. and Procolo Lucignano
Josephson devices with ferromagnetic barriers have been widely studied. Much less is known when the ferromagnetic layer is insulating. In this manuscript we investigate the transport
properties of superconductor- ferromagnetic insulator-superconductor (SFIS) junctions with particular attention to the temperature behavior of the critical current, that may be used as a fingerprint of the junction. We investigate the specific role of impurities as well as of possible spin mixing mechanisms, due to the spin orbit coupling. Transition between the 0 and the {\pi} phases can be properly tuned, thus achieving stable {\pi} junctions over the whole temperature range, that may be possibly employed in superconducting quantum circuits
arxiv pdf