Photon-assistant Fano resonance in coupled multiple quantum dots

TL;DR

This paper investigates photon-assisted Fano resonances in coupled quantum dots, revealing how different configurations and energy levels influence transport properties and enabling control of Fano effects in quantum electronics.

Contribution

It provides a detailed analysis of photon-assisted Fano resonances in coupled quantum dots, highlighting the role of energy levels and configurations in transport phenomena.

Findings

Photon-assisted Fano resonances occur in parallel DQDs.

Symmetric resonances appear in serial DQDs.

Dark states enable Fano line shapes in symmetric configurations.

Abstract

Based on calculations of the electronic structure of coupled multiple quantum dots, we study systemically the transport properties of the system driven by an ac electric field. We find qualitative difference between transport properties of double coupled quantum dots (DQDs) and triple quantum dots. For both symmetrical and asymmetrical configurations of coupled DQDs, the field can induce the photon-assisted Fano resonances in current-AC frequency curve in parallel DQDs, and a symmetric resonance in serial DQDs. For serially coupled triple quantum dots(STQDs), it is found that the $\Lambda$-type energy level has remarkable impact on the transport properties. For an asymmetric (between left and right dots) configuration, there is a symmetric peak due to resonant photon induced mixing between left/right dot and middle dot. In the symmetric configuration, a Fano asymmetric line shape appears with the help of ``trapping dark state". Here the interesting coherent trapping phenomena, which usual appear in quantum optics, play an essential role in quantum electronic transport. We provide a clear physics picture for the Fano resonance and convenient ways to tune the Fano effects.