# Voltage-controlled two-dimensional Fresnel diffraction pattern in quantum dot molecules

## TL;DR

This paper shows how quantum dot molecules can control Fresnel diffraction patterns using tunneling effects and orbital angular momentum.

## Contribution

The study introduces voltage-controlled manipulation of Fresnel diffraction patterns using inter-dot tunneling and LG coupling fields.

## Key findings

- Inter-dot tunneling and coupling field strength control the spatial distribution of Fresnel diffraction patterns.
- Negative orbital angular momentum in LG fields inverts the diffraction pattern's shape.
- Tunneling effects disrupt symmetry in diffraction patterns and depend on the helical phase front direction.

## Abstract

This study explores the influence of inter-dot tunneling effects within a quantum dot molecule on the Fresnel diffraction phenomenon. Our findings indicate that the Fresnel diffraction of the output probe Gaussian field can be manipulated by adjusting the inter-dot tunneling parameter’s strength and the characteristics of the coupling field. The inter-dot tunneling effect establishes a closed-loop system, setting conditions for the interference of the applied fields. We specifically examine a Laguerre–Gaussian (LG) coupling field, investigating how its properties-such as strength, value, and sign of the orbital angular momentum (OAM)-impact the Fresnel diffraction of the output probe field. Increasing the inter-dot tunneling parameter and the coupling LG field’s strength allows for control over the spatial distribution of the Fresnel diffraction pattern. Notably, the inter-dot tunneling parameter can disturb the symmetry of the diffraction patterns. Additionally, considering a negative OAM for the coupling LG field transforms the diffraction pattern into its inverse shape. This suggests that, in the presence of the inter-dot tunneling effect, the Fresnel diffraction pattern is contingent on the direction of rotation of the helical phase front of the coupling LG field. Our results offer insights into quantum control of Fresnel diffraction patterns and the identification of OAM in LG beams, presenting potential applications in quantum technologies.