Resonant tunneling through an Anderson impurity. II. Noise in the Hartree approximation

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Abstract
We compute the zero-frequency current noise for resonant tunneling through an Anderson impurity in the Hartree approximation and show that the noise in the presence of interactions has a qualitatively different structure than the noise in the absence of interactions. This difference is due to the coupling of the current fluctuations to the density fluctuations at the impurity by the on-site Coulomb repulsion. The noninteracting current noise is only sensitive to the transmission probability through the tunnel junction. Depending on the relative size of the tunneling rates onto the impurity and the placement of the impurity level relative to the chemical potentials in the leads, the interacting correction to the noise can be either positive or negative. By deriving an expression for the noise valid for tunneling through an arbitrary interacting region between two perfect leads, we are able to show how this coupling of the current fluctuations to other kinds of fluctuations takes place in general.