Stability of superconducting resonators: Motional narrowing and the role of Landau-Zener driving of two-level defects
Artikel i vetenskaplig tidskrift, 2021

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.

Coplanar waveguides


Energy dissipation

Microwave resonators

Niobium compounds

Natural frequencies


David Niepce

Chalmers, Mikroteknologi och nanovetenskap, Kvantteknologi

J. Burnett

National Physical Laboratory (NPL)

Marina Kudra

Chalmers, Mikroteknologi och nanovetenskap, Kvantteknologi

Jared H. Cole

RMIT University

Jonas Bylander

Chalmers, Mikroteknologi och nanovetenskap, Kvantteknologi

Science advances

2375-2548 (eISSN)

Vol. 7 39 eabh0462


Annan fysik

Strömningsmekanik och akustik

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