Superconducting granular aluminum resonators resilient to magnetic fields up to 1 Tesla

  1. K. Borisov,
  2. D. Rieger,
  3. P. Winkel,
  4. F. Hernandez,
  5. F. Valenti,
  6. A. Ionita,
  7. M. Wessbecher,
  8. M. Spiecker,
  9. D. Gusenkova,
  10. I. M. Pop,
  11. and W. Wernsdorfer
High kinetic inductance materials constitute a valuable resource for superconducting quantum circuits and hybrid architectures. Superconducting granular aluminum (grAl) reaches kinetic sheet inductances in the nH/â–¡ range, with proven applicability in superconducting quantum bits and microwave detectors. Here we show that the single photon internal quality factor Qi of grAl microwave resonators exceeds 105 in magnetic fields up to 1T, aligned in-plane to the grAl films. Small perpendicular magnetic fields, in the range of 0.5mT, enhance Qi by approximately 15%, possibly due to the introduction of quasiparticle traps in the form of fluxons. Further increasing the perpendicular field deteriorates the resonators‘ quality factor. These results open the door for the use of high kinetic inductance grAl structures in circuit quantum electrodynamics and hybrid architectures with magnetic field requirements.
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