Hydrogen-like impurity, polarization and thickness effect on the properties of a two-level system in a Gaussian confinement potential well with electric-field

Abstract

We select the asymmetric Gaussian (AG) and the parabolic (P) confinement to describe the along growth direction and perpendicular to growth direction confinement potential (CP) of an electron in a disk-like quantum dot (QD), respectively. Using the Pekar-type variational (PTV) method, we investigate the eigenenergies of the ground and first-excited states (GFES) of the polaron in the QD, changing the QD dimensions. We study the hydrogen-like impurity (HLI) and the polarization effect. Our numerical results show the influence of the QD dimensions on the mean number of phonons, energies, transition frequency and probability. The Coulomb potential of hydrogen-like impurity and the polarization effect of the medium cannot be ignored. We find that the electric field is an indispensable condition for the induced polaron transition. The weak electric field has a strong regulatory function on the transition. AG confinement is more drastic than P confinement in modulating polaron transition properties. This work confirms that the choice of a CP is crucial for the study of polaron transition in nanostructures. This quantum system can be employed as a two-level quantum qubit.