Influence of Disorder on Exciton Transfer in a Quantum Dot Chain with Short-Range Interaction and a Side-Coupled Defect

TL;DR

This study investigates how structural disorder affects exciton transfer in a quantum dot chain with a side defect, revealing localization phenomena and phase transition boundaries relevant for quantum information applications.

Contribution

It introduces a model for exciton dynamics in disordered QD chains with a side defect, analyzing localization and phase transition criteria.

Findings

Localization depends on disorder magnitude and chain length

A phase transition boundary between localized and delocalized states is identified

Dynamic localization correlates with stationary state localization

Abstract

This paper considers the propagation of excitons in linear chains of QDs with a side defect, located on a dielectric substrate. This configuration is suitable for spatially selective excitation of the system by pulsed optical radiation through the side defect. The dynamics of excitation in the chain is governed by structural disorder, caused by technological variations in the parameters of the QDs themselves and their mutual arrangement. To describe the quantum properties of excitons in the QD chain, a model Hamiltonian is used, taking into account the coupling of neighboring QDs due to dipole-dipole interaction. The localization of stationary states is calculated depending on the magnitude of disorder and the chain length. A criterion is introduced that determines the boundaries of the phase transition from the localized to the delocalized excitation phase. The dynamics of exciton transfer along the QD chain is calculated depending on its length and degree of disorder for linear excitation of the system by a laser pulse. It is shown that dynamic localization emerging in the system corresponds to the stationary localization properties of the states of the chain with a side defect.