Absence of bimodal peak spacing distribution in the Coulomb blockade regime

TL;DR

This paper demonstrates through numerical and analytical methods that in the Coulomb blockade regime, the peak spacing distribution in chaotic and disordered quantum dots is Gaussian, aligning with experimental results, and predicts a spin polarization effect.

Contribution

It provides the first analytical and numerical evidence that the peak spacing distribution is Gaussian, not bimodal, and links this to electron interactions and spin polarization effects.

Findings

Peak spacing distribution is Gaussian in typical quantum dots.

Electron interactions lead to non-trivial spin polarization.

Experimental tests for spin polarization are proposed.

Abstract

Using exact diagonalization numerical methods, as well as analytical arguments, we show that for the typical electron densities in chaotic and disordered dots the peak spacing distribution is not bimodal, but rather Gaussian. This is in agreement with the experimental observations. We attribute this behavior to the tendency of an even number of electrons to gain on-site interaction energy by removing the spin degeneracy. Thus, the dot is predicted to show a non trivial electron number dependent spin polarization. Experimental test of this hypothesis based on the spin polarization measurements are proposed.