Fano stability diagram of a symmetric triple quantum dot

TL;DR

This paper investigates the Fano factor stability diagram of a symmetric triangular quantum dot, revealing how electron filling influences noise behavior, including electron bunching mechanisms due to degeneracies and interference effects.

Contribution

It provides a detailed analysis of the Fano factor in a symmetric triple quantum dot, highlighting the transition from Poissonian to super-Poissonian noise with increasing electron filling and elucidating the underlying electron bunching mechanisms.

Findings

Low filling shows Poissonian/sub-Poissonian noise behavior.

Higher filling exhibits super-Poissonian noise with bias dependence.

Degenerate states and interference lead to electron bunching.

Abstract

The Fano factor stability diagram of a C$_{3v}$ symmetric triangular quantum dot is analysed for increasing electron fillings $N$. At low filling, conventional Poissonian and sub-Poissonian behavior is found. At larger filling, $N\ge 2$, a breaking of the electron-hole symmetry is manifested in super-Poissonian noise with a peculiar bias voltage dependence of the Fano factor at Coulomb and interference blockade. An analysis of the Fano map unravels a nontrivial electron bunching mechanism arising from the presence of degenerate many-body states combined with orbital interference and Coulomb interactions. An expression for the associated dark states is provided for generic $N$.