Formation of Fano resonance in double quantum dot system

TL;DR

This paper investigates the transient electron dynamics and Fano resonance formation in a double quantum dot system, highlighting how coupling strengths influence transport behavior, resonance development, and entanglement evolution.

Contribution

It provides new insights into how weak and strong inter-dot couplings affect the time evolution of transport and resonance formation in a double quantum dot system.

Findings

Fano resonance forms more slowly with weak coupling.

Single relaxation time dominates in strong coupling.

Rapid Rabi oscillations observed in strong coupling regime.

Abstract

Transient electron dynamics and the Fano resonance formation over time in transport through a two quantum dot system in a T-shape geometry (2QD-T) are analysed for free electrons. Time evolution of the transport characteristics are different for a weak and a strong inter-dot coupling with respect to the dot-electrode coupling. When the dot-dot coupling is weak, we find that transport dynamics is governed by two channel tunneling processes with two different relaxation times and buildup of the Fano resonance is developed much slower, with the longer relaxation time. In the opposite limit, the transmission evolves with a single relaxation time, from the single peak resonance structure into the structure with two asymmetric peaks. One observes large dot-electrode charge oscillations, which can temporarily change direction of transient currents. We find also that the time evolution of entanglement is different in both coupling regimes; in particular rapid Rabi oscillations caused by coherent electron transfer between the 2QD states can be seen for the strong dot-dot coupling.