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TT 31: Superconducting Electronics: SQUIDs, Qubits, Circuit QED, Quantum Coherence and Quantum Information Systems 1
TT 31.9: Vortrag
Mittwoch, 18. März 2020, 11:45–12:00, HSZ 03
Superconducting granular aluminum resonators resilient to magnetic fields up to 1 Tesla — •Alexandru Ionita, Kiril Borisov, Dennis Rieger, Patrick Winkel, Markus Weßbecher, Fabio Henriques, Francesco Valenti, Martin Spiecker, Daria Gusenkova, Wolfgang Wernsdorfer, and Ioan Pop — Physikalisches Institut, KIT, Karlsruhe, Germany
Superconducting granular aluminum (grAl) is an attractive high-kinetic inductance material with proven applicability in superconducting qubits [1, 2] and microwave detectors . As the magnetic field is a double-edged sword, which provides an important control knob to superconducting circuits but could also lead to higher quasiparticle population and induced vortices, we investigate the field resilience of grAl superconducting resonators. We carried out reflection measurements in both in-plane and perpendicular external magnetic fields, which tune the resonance frequency by up to 70 MHz. The internal quality factor remains on the order of 105 in the single photon regime under in-plane magnetic field up to 1 T . Moderate perpendicular field has a beneficial effect on the resonator properties and leads to a small increase of the internal quality factor by 15 %. We further discuss the field-dependence of self-Kerr coefficient , rate of quasiparticle relaxation  and coupling to spin-1/2 magnetic impurities.
 L. Grünhaupt, M. Spiecker, Nat. Mat. 18(8), 816 (2019).
 P. Winkel, arXiv: 1911.02333
 F. Valenti, Phys. Rev. Appl. 11, 054087 (2019
 K. Borisov (in preparation)
 N. Maleeva, Nat. Comm. 9(1), 3889 (2018)