| Autor: |
Niepce D; Chalmers University of Technology, Microtechnology, and Nanoscience, SE-41296 Gothenburg, Sweden., Burnett JJ; National Physical Laboratory, Hampton Road, Teddington Middlesex TW11 0LW, UK., Kudra M; Chalmers University of Technology, Microtechnology, and Nanoscience, SE-41296 Gothenburg, Sweden., Cole JH; Chemical and Quantum Physics, School of Science, RMIT University, Melbourne, VIC 3001, Australia., Bylander J; Chalmers University of Technology, Microtechnology, and Nanoscience, SE-41296 Gothenburg, Sweden. |
| Abstrakt: |
Frequency instability of superconducting resonators and qubits leads to dephasing and time-varying energy loss and hinders quantum processor tune-up. Its main source is dielectric noise originating in surface oxides. Thorough noise studies are needed to develop a comprehensive understanding and mitigation strategy of these fluctuations. We use a frequency-locked loop to track the resonant frequency jitter of three different resonator types—one niobium nitride superinductor, one aluminum coplanar waveguide, and one aluminum cavity—and we observe notably similar random telegraph signal fluctuations. At low microwave drive power, the resonators exhibit multiple, unstable frequency positions, which, for increasing power, coalesce into one frequency due to motional narrowing caused by sympathetic driving of two-level system defects by the resonator. In all three devices, we identify a dominant fluctuator whose switching amplitude (separation between states) saturates with increasing drive power, but whose characteristic switching rate follows the power law dependence of quasi-classical Landau-Zener transitions. |
