Enhancement of the indistinguishability of single photon emitters coupled to photonic waveguides

TL;DR

This paper presents an analytical model and numerical simulations to optimize the coupling and indistinguishability of single photon emitters integrated with photonic waveguides, crucial for scalable quantum photonics.

Contribution

The work introduces a new analytical model for emitter-waveguide coupling and indistinguishability, validated by FDTD simulations, highlighting optimal emitter placement for quantum photonic integration.

Findings

Maximum coupling occurs at the waveguide center.

Maximum indistinguishability occurs at the waveguide edge.

Surface discontinuity enhances electric field and photon indistinguishability.

Abstract

One of the main steps towards large-scale quantum photonics consists of the integration of single photon sources (SPS) with photonic integrated circuits (PICs). For that purpose, the PICs should offer an efficient light coupling and a high preservation of the indistinguishability of photons. Therefore, optimization of the indistinguishability through waveguide design is especially relevant. In this work we have developed an analytical model to calculate the coupling and the indistinguishability of an ideal point-source quantum emitter coupled to a photonic waveguide depending on source orientation and position. The model has been numerically evaluated through finite-difference time-domain (FDTD) simulations showing consistent results. The maximum coupling is achieved when the emitter is embedded in the center of the waveguide but somewhat surprisingly the maximum indistinguishability appears when the emitter is placed at the edge of the waveguide where the electric field is stronger due to the surface discontinuity.