AQP Seminar: Electrical low-frequency 1/f^γ noise due to surface diffusion of scatterers on an ultralow noise graphene platform

Aalto Quantum Physics Seminars (Zoom). Speaker: Weijun Zeng (Low Temperature Laboratory, Department of Applied Physics, Aalto University)
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Low-frequency 1/fγ noise is ubiquitous, even in high-end electronic devices. For qubits, such noise results in decreasing their coherence times. Recently, it was found that adsorbed O2 molecules provide the dominant contribution to flux noise in superconducting quantum interference devices. To clarify the basic principles of such adsorbent noise, we have investigated the formation of low-frequency noise while the mobility of surface adsorbents is varied by temperature. In our experiments, we measured low-frequency current noise in suspended monolayer graphene samples under the influence of adsorbed Ne atoms. Owing to the extremely small intrinsic noise of graphene in suspended Corbino geometry, we could resolve a combination of 1/fγ and Lorentzian noise spectra induced by the presence of Ne. We find that the 1/fγ noise is caused by the surface diffusion of Ne atoms and by the temporary formation of few-Ne-atom clusters. Our results support the idea that clustering dynamics of defects is relevant for understanding 1/f noise in general metallic systems.

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