Modeling high-order harmonic generation in quantum dots using a real-space tight-binding approach

TL;DR

This paper introduces a real-space tight-binding computational model to simulate high-order harmonic generation in quantum dots, accurately capturing size-dependent behaviors and extending the ability to study medium-sized nanostructures under strong fields.

Contribution

The paper presents a novel, efficient 3D tight-binding model derived from DFT and Wannierization, specifically designed for simulating HHG in confined quantum dot systems.

Findings

Model accurately reproduces size-dependent HHG yield.

Simulates HHG under elliptically polarized pulses up to 5 μm wavelength.

Fills a theoretical gap for medium-sized nanostructure HHG simulation.

Abstract

Recently, the size-dependence of high-order harmonic generation (HHG) in quantum dots has been investigated experimentally. In particular, for longer driving wavelengths and QDs smaller than 3\,nm, HHG was strongly suppressed, however, there is no computational model capable of describing the strong-field response of such systems. In this work, we introduce a computationally efficient three-dimensional real-space tight-binding model specifically designed for the simulation of HHG in confined systems. The model parameters are meticulously derived from density functional theory (DFT) calculations for the semiconductor bulk, followed by a process of Wannierization. Our findings demonstrate that the proposed model accurately captures the observed dependency of the HHG yield on the quantum dot size. Additionally, we simulate the HHG yield for elliptically polarized pulses for different QD-sizes and driving wavelengths up to $5\,\mu{\mathrm{m}}$. The herein proposed model fills the theoretical void in simulating HHG within medium-sized nanostructures, which cannot be described by methods applied for periodic solids or small molecules or atoms.