# Indistinguishable photons from deterministically integrated single quantum dots in heterogeneous GaAs/Si$_3$N$_4$ quantum photonic circuits

## TL;DR

This paper demonstrates the deterministic integration of single quantum dots into GaAs/Si3N4 photonic circuits, producing on-demand indistinguishable single-photon sources crucial for scalable quantum photonic networks.

## Contribution

It introduces a scalable fabrication method for precisely positioning quantum dots in photonic circuits, enabling on-chip generation of indistinguishable single photons.

## Key findings

- Successful deterministic placement of quantum dots within nanophotonic structures.
- Observation of post-selected indistinguishable photons from integrated sources.
- Potential for scaling up chip-based quantum photonic systems.

## Abstract

Silicon photonics enables scaling of quantum photonic systems by allowing the creation of extensive, low-loss, reconfigurable networks linking various functional on-chip elements. Inclusion of single quantum emitters onto photonic circuits, acting as on-demand sources of indistinguishable photons or single-photon nonlinearities, may enable large-scale chip-based quantum photonic circuits and networks. Towards this, we use low-temperature $\textit{in situ}$ electron-beam lithography to deterministically produce hybrid GaAs/Si$_3$N$_4$ photonic devices containing single InAs quantum dots precisely located inside nanophotonic structures, which act as efficient, Si$_3$N$_4$ waveguide-coupled on-chip, on-demand single-photon sources. The precise positioning afforded by our scalable fabrication method furthermore allows observation of post-selected indistinguishable photons. This indicates a promising path towards significant scaling of chip-based quantum photonics, enabled by large fluxes of indistinguishable single-photons produced on-demand, directly on-chip.