High-yield fabrication of entangled photon emitters for hybrid quantum networking using high-temperature droplet epitaxy

TL;DR

This paper presents a high-temperature droplet epitaxy method on (111)A substrates that significantly enhances the yield of entanglement-ready quantum dot photon emitters, advancing quantum networking capabilities.

Contribution

The authors introduce a modified droplet epitaxy technique at high temperature on (111)A substrates, achieving up to 95% yield of entanglement-ready quantum dots with suitable emission wavelengths.

Findings

Yield of entanglement-ready quantum dots increased to 95%.

Low fine structure splitting and radiative lifetime improve entanglement quality.

Emission wavelength matches Rb-based quantum memory requirements.

Abstract

Several semiconductor quantum dot techniques have been investigated for the generation of entangled photon pairs. Among the other techniques, droplet epitaxy enables the control of the shape, size, density, and emission wavelength of the quantum emitters. However, the fraction of the entanglement-ready quantum dots that can be fabricated with this method is still limited to around 5%, and matching the energy of the entangled photons to atomic transitions (a promising route towards quantum networking) remains an outstanding challenge. Here, we overcome these obstacles by introducing a modified approach to droplet epitaxy on a high symmetry (111)A substrate, where the fundamental crystallization step is performed at a significantly higher temperature as compared to previous reports. Our method drastically improves the yield of entanglement-ready photon sources near the emission wavelength of interest, which can be as high as 95% due to the low values of fine structure splitting and radiative lifetime, together with the reduced exciton dephasing offered by the choice of GaAs/AlGaAs materials. The quantum dots are designed to emit in the operating spectral region of Rb-based slow-light media, providing a viable technology for quantum repeater stations.