Interference Effect in Multi-level Transport through a Quantum Dot

TL;DR

This paper investigates Fano-type interference effects in quantum dot transport, revealing phase locking and interference phenomena between energy levels, supported by experimental data and a theoretical model.

Contribution

It introduces a model explaining in-phase Coulomb peaks and interference effects in quantum dots, supported by experimental observations.

Findings

Observation of Fano-type interference between energy levels

Detection of phase change at Coulomb diamond vertices

Evidence of phase locking to strongly coupled level

Abstract

We present experimental results and a model to solve the problem of "in-phase Coulomb peaks" observed in transport through a quantum dot. In a marginal region between Coulomb-blockade and open-dot, we have observed Fano-type interference through two energy levels inside the dot, which manifest themselves in two overlapped Coulomb-diamond-like structures in the excitation spectrum. One of the two levels is strongly coupled to the leads and the phase of traversing electrons is locked to it. We have detected the phase change at the vertices and the centers of the larger diamonds through the sign of the Fano's asymmetric parameters supporting the above deduction.