Magnetically driven coupling of electronic states in quantum dot molecules

Abstract

We consider lowest energy states of electrons confined in asymmetrical circular vertically stacked double InAs/GaAs quantum dot molecule. The energies where computed by using the effective three-dimensional one band Hamiltonian, the energy (non-parabolic) and position dependent electronic effective mass approximation, and the Ben Daniel-Duke boundary conditions with the finite hard wall confinement potential. We demonstrated theoretically a possibility to drive dynamically coupled electronic states (relocate electronic wave functions from one dot to another) by applying external magnetic field.1 Introduction Recent advances in the fabrication of semiconductor nano-scale-objects stimulated much attention to the study of structural, optical, and electronic properties of semiconductor quantum dots (see for example [1]). Especially, during the last decade it has become possible to fabricate realistic semiconductor quantum dots in laboratories. Various experimental results demonstrate that InAs/GaAs quantum dots can have diverse shapes, such as disk, ellipsoid, or conical shapes with a circular top view cross section and a large area-to-height aspect ratio (see for instance [2,3]). Coupled quantum dots allow us to form an artificial molecule. In this molecule we can adjust the inter-dot distance and through that to control coupling between electronic states localized in different dots. The ability to control coherent coupling between double quantum dots may open possibility for designing quantum logic gates (see [4,5] and references therein). The inter-dot distance control is an example of a static approach to the gate's design. Another possibility to control dynamically the coupling lies in application of external fields [6].In this work we demonstrate theoretically an opportunity to drive dynamically electronic states by applying external magnetic field to two vertically coupled InAs/GaAs quantum dots.

Left handed composite materials in the optical range

“…Recent advances in the manufacturing of semiconductor nano-rings make it possible to construct arrays of III-V semiconductor nano-scale rings [5]. Just like selfassembled quantum dots, nano-rings posses atom-like optical properties, but at the same time nano-rings are non-simply connected quantum systems, exhibiting unusual magnetic [6][7][8] and magneto-optical properties [5,9,10]. One of the problems arising in LHCMs for the optical range is that the size of the structural elements has to be of nanometer scale.…”