Coulomb blockade peak spacing fluctuations in deformable quantum dots: a further test to Random Matrix Theory

TL;DR

This paper explains how shape deformations in quantum dots can cause Coulomb blockade peak spacing fluctuations, shifting the distribution from Wigner-Dyson to Gaussian, aligning with recent experimental observations.

Contribution

It introduces a mechanism linking shape deformations to peak spacing fluctuations using random matrix theory, expanding understanding of quantum dot behavior without relying on strong charging energy fluctuations.

Findings

Peak spacing distribution can shift from Wigner-Dyson to Gaussian due to shape deformations.

Distribution depends on the number of anti-crossings and magnetic field presence.

Results agree with recent experimental data on quantum dots.

Abstract

We propose a mechanism to explain the fluctuations of the ground state energy in quantum dots in the Coulomb blockade regime. Employing the random matrix theory we show that shape deformations may change the adjacent peak spacing distribution from Wigner-Dyson to nearly Gaussian even in the absence of strong charging energy fluctuations. We find that this distribution is solely determined by the average number of anti-crossings between consecutive conductance peaks and the presence or absence of a magnetic field. Our mechanism is tested in a dynamical model whose underlying classical dynamics is chaotic. Our results are in good agreement with recent experiments and apply to quantum dots with spin resolved or spin degenerate states.