  Magnetic and charge noise have common microscopic origin in solid state
devices, as described by a universal electron trap model. In spite of this
common origin, magnetic (spin) and charge noise spectral densities display
remarkably different behaviours when many-particle correlations are taken into
account, leading to the emergence of the Kondo effect. Our numerical
renormalization group results indicate that while spin noise is a universal
function of the Kondo temperature, charge noise remains well described by
single-particle theory even when the trap is deep in the Kondo regime. This
difference survives even in the presence of disorder, showing that noise can be
more manageable in devices that are sensitive to magnetic (rather than charge)
fluctuations and that the signature of the Kondo effect can be observed in spin
noise spectroscopy experiments.

Mesoscale and Nanoscale Physics;Strongly Correlated Electrons