In-plane resonant excitation of quantum dots in a dual-mode photonic-crystal waveguide with high $\beta$-factor

TL;DR

This paper introduces a dual-mode photonic-crystal waveguide that enables stable, high-efficiency in-plane resonant excitation of quantum dots, significantly improving single-photon source performance for quantum information processing.

Contribution

It presents a novel waveguide design that allows direct resonant excitation and high collection efficiency of quantum dot emissions in a compact, scalable device.

Findings

Single-photon collection efficiency > 95%

Impurity of emitted photons < 0.005

Broad spectral and spatial operational range

Abstract

A high-quality quantum dot (QD) single-photon source is a key resource for quantum information processing. Exciting a QD emitter resonantly can greatly suppress decoherence processes and lead to highly indistinguishable single-photon generation. It has, however, remained a challenge to implement strict resonant excitation in a stable and scalable way, without compromising any of the key specs of the source (efficiency, purity, and indistinguishability). In this work, we propose a novel dual-mode photonic-crystal waveguide that realizes direct in-plane resonant excitation of the embedded QDs. The device relies on a two-mode waveguide design, which allows exploiting one mode for excitation of the QD and the other mode for collecting the emitted single photons with high efficiency. By proper engineering of the photonic bandstructure, we propose a design with single-photon collection efficiency of $\beta > 0.95$ together with a single-photon impurity of $\epsilon< 5 \times 10^{-3}$ over a broad spectral and spatial range. The device has a compact footprint of $\sim 50$ $\mu$m$^2$ and would enable stable and scalable excitation of multiple emitters for multi-photon quantum applications.