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Origin and Reduction of 1=f Magnetic Flux Noise in Superconducting Devices



P Kumar, David P. Pappas, Robert Mcdermott, J.W. Freeland, Clare Yu, M Beck, Hui Wang, Ruqian Wu


Magnetic flux noise is a dominant source of dephasing and energy relaxation in superconducting qubits. The noise power spectral density varies with frequency as 1=f^α, with α ≲ 1, and spans 13 orders of magnitude. Recent work indicates that the noise is from unpaired magnetic defects on the surfaces of the superconducting devices. Here, we demonstrate that adsorbed molecular O_2 is the dominant contributor to magnetism in superconducting thin films. We show that this magnetism can be reduced by appropriate surface treatment or improvement in the sample vacuum environment. We observe a suppression of static spin susceptibility by more than an order of magnitude and a suppression of 1=f magnetic flux noise power spectral density of up to a factor of 5. These advances open the door to the realization of superconducting qubits with improved quantum coherence.
Journal of Superconductivity


Magnetic flux noise, superconductivity, SQUID


Kumar, P. , Pappas, D. , Mcdermott, R. , Freeland, J. , Yu, C. , Beck, M. , Wang, H. and Wu, R. (2016), Origin and Reduction of 1=f Magnetic Flux Noise in Superconducting Devices, Journal of Superconductivity, [online],, (Accessed May 27, 2024)


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Created October 17, 2016, Updated October 12, 2021