We propose a model for 1/f flux noise in superconducting devices (f is frequency). The noise is generated by the magnetic moments of electrons in defect states which they occupy for a wide distribution of times before escaping. A trapped electron occupies one of the two Kramers-degenerate ground states, between which the transition rate is negligible at low temperature. As a result, the magnetic moment orientation is locked. Simulations of the noise produced by randomly oriented defects with a density of 5*10^17 m^-2 yield 1/f noise magnitudes in good agreement with experiments.
@article{arxiv.cond-mat/0702025,
title = {Model for l/f Flux Noise in SQUIDs and Qubits},
author = {Roger H. Koch and David P. DiVincenzo and John Clarke},
journal= {arXiv preprint arXiv:cond-mat/0702025},
year = {2009}
}
Comments
16 pages, 4 figures; v2: Various minor changes. Physical Review Letters, in press