Double quantum dot in a quantum dash: optical properties

TL;DR

This paper investigates the optical properties of anisotropic quantum dash structures with two trapping centers, revealing the formation of sub- and super-radiant states and how geometry influences absorption spectra and polarization.

Contribution

It demonstrates the formation of collective states in double trapping center quantum dashes and analyzes how geometry affects their optical absorption and polarization properties.

Findings

Sub- and super-radiant states can form depending on geometry.

The ground state absorption is often stronger than excited states.

Geometry of trapping centers significantly influences optical responses.

Abstract

We study the optical properties of highly anisotropic quantum dot structures (quantum dashes) characterized by the presence of two trapping centers located along the structure. Such a system can exhibit some of the properties characteristic for double quantum dots. We show that sub- and super-radiant states can form for certain quantum dash geometries, which is manifested by a pronounced transfer of intensity between spectral lines, accompanied by the appearance of strong electron-hole correlations. We also compare exciton absorption spectra and polarization properties of a system with a single and double trapping center and show how the geometry of multiple trapping centers influences the optical properties of the system. We show that for a broad range of trapping geometries the relative absorption intensity of the ground state is larger than that of the lowest excited states, contrary to the quantum dash systems characterized by a single trapping center. Thus, optical properties of these structures are determined by fine details of their morphology.