TY  - JOUR
AU  - Grünhaupt, Lukas
AU  - Maleeva, Nataliya
AU  - Skacel, Sebastian T.
AU  - Calvo, Martino
AU  - Levy-Bertrand, Florence
AU  - Ustinov, Alexey V.
AU  - Rotzinger, Hannes
AU  - Monfardini, Alessandro
AU  - Catelani, Gianluigi
AU  - Pop, Ioan M.
TI  - Loss Mechanisms and Quasiparticle Dynamics in Superconducting Microwave Resonators Made of Thin-Film Granular Aluminum
JO  - Physical review letters
VL  - 121
IS  - 11
SN  - 1079-7114
CY  - College Park, Md.
PB  - APS
M1  - FZJ-2018-05287
SP  - 117001
PY  - 2018
AB  - Superconducting high kinetic inductance elements constitute a valuable resource for quantum circuit design and millimeter-wave detection. Granular aluminum (grAl) in the superconducting regime is a particularly interesting material since it has already shown a kinetic inductance in the range of nH/□ and its deposition is compatible with conventional Al/AlOx/Al Josephson junction fabrication. We characterize microwave resonators fabricated from grAl with a room temperature resistivity of 4×103  μΩ cm, which is a factor of 3 below the superconductor to insulator transition, showing a kinetic inductance fraction close to unity. The measured internal quality factors are on the order of Qi=105 in the single photon regime, and we demonstrate that nonequilibrium quasiparticles (QPs) constitute the dominant loss mechanism. We extract QP relaxation times in the range of 1 s and we observe QP bursts every ∼20  s. The current level of coherence of grAl resonators makes them attractive for integration in quantum devices, while it also evidences the need to reduce the density of nonequilibrium QPs.
LB  - PUB:(DE-HGF)16
C6  - pmid:30265102
UR  - <Go to ISI:>//WOS:000444586600016
DO  - DOI:10.1103/PhysRevLett.121.117001
UR  - https://juser.fz-juelich.de/record/851772
ER  -