Statistics of the Coulomb blockade peak spacings of a silicon quantum dot

TL;DR

This paper experimentally investigates Coulomb blockade peak fluctuations in a silicon quantum dot, revealing that the peak spacings are unimodal, larger than single-particle levels, and do not follow random matrix theory predictions.

Contribution

It provides the first detailed statistical analysis of Coulomb blockade peak spacings in silicon quantum dots, highlighting deviations from theoretical expectations.

Findings

Peak spacings are unimodal and do not follow Wigner surmise.

Spacing fluctuations are larger than single-particle energy levels.

Results contradict predictions of random matrix theory.

Abstract

We present an experimental study of the fluctuations of Coulomb blockade peak positions of a quantum dot. The dot is defined by patterning the two-dimensional electron gas of a silicon MOSFET structure using stacked gates. This permits variation of the number of electrons on the quantum dot without significant shape distortion. The ratio of charging energy to single particle energy is considerably larger than in comparable GaAs/AlGaAs quantum dots. The statistical distribution of the conductance peak spacings in the Coulomb blockade regime was found to be unimodal and does not follow the Wigner surmise. The fluctuations of the spacings are much larger than the typical single particle level spacing and thus clearly contradict the expectation of random matrix theory.