Details

Autor(en) / Beteiligte

• Grünhaupt, Lukas
• Maleeva, Nataliya
• Skacel, Sebastian T
• Calvo, Martino
• Levy-Bertrand, Florence
• Ustinov, Alexey V
• Rotzinger, Hannes
• Monfardini, Alessandro
• Catelani, Gianluigi
• Pop, Ioan M

Titel

Loss Mechanisms and Quasiparticle Dynamics in Superconducting Microwave Resonators Made of Thin-Film Granular Aluminum

Ist Teil von

• Physical review letters, 2018-09, Vol.121 (11), p.117001-117001, Article 117001

Ort / Verlag

United States: American Physical Society

Erscheinungsjahr

2018

Quelle

American Physical Society Journals

Beschreibungen/Notizen

• 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 4×10^{3}  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 Q_{i}=10^{5} 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.