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

Area of Science:

• Quantum optics
• Condensed matter physics
• Computational materials science

Background:

• High-order harmonic generation (HHG) is crucial for ultrafast science.
• Experimental studies show size-dependent HHG in quantum dots (QDs), especially suppression in smaller QDs (<3 nm) at longer wavelengths.
• Existing computational models fail to describe the strong-field response of these nanostructures.

Purpose of the Study:

• To develop a computationally efficient 3D real-space tight-binding model for simulating HHG in confined systems like QDs.
• To validate the model against experimental observations of size-dependent HHG.
• To extend simulations to larger QDs and longer driving wavelengths, including elliptical polarization.

Main Methods:

• Developed a 3D real-space tight-binding model.
• Derived model parameters from density functional theory (DFT) calculations and Wannierization.
• Simulated HHG yield for varying QD sizes and driving wavelengths (up to 5 μm).
• Investigated HHG under elliptically polarized pulses.

Main Results:

• The model accurately reproduces the experimentally observed size-dependence of HHG yield in QDs.
• Simulations show good agreement with experimental data for HHG suppression in small QDs.
• The model successfully simulates HHG for various QD sizes and long driving wavelengths.

Conclusions:

• The proposed tight-binding model provides a robust theoretical framework for simulating HHG in medium-sized nanostructures.
• This work bridges the gap between theoretical models and experimental findings in QD HHG.
• The model enables further exploration of strong-field phenomena in nanostructured materials.