Purification of single photons by temporal heralding of quantum dot sources

TL;DR

This paper introduces two temporal heralding methods to purify single photon emission from quantum dots, achieving over 99.5% purity without spectral filtering, enhancing quantum photonic applications.

Contribution

The paper presents novel temporal heralding techniques for quantum dot sources, enabling high-purity single photon emission without spectral filtering, demonstrated experimentally.

Findings

Single photon purity exceeds 99.5%

Methods applicable to broadband photon pair sources

High efficiency maintained during purification

Abstract

Efficient, high rate photon sources with high single photon purity are essential ingredients for quantum technologies. Single photon sources based on solid state emitters such as quantum dots are very advantageous for integrated photonic circuits, but they can suffer from a high two-photon emission probability, which in cases of non-cryogenic environment cannot be spectrally filtered. Here we propose two temporal purification-by-heralding methods for using a two photon emission process to yield highly pure and efficient single photon emission, bypassing the inherent problem of spectrally overlapping bi-photon emission. We experimentally demonstrate their feasibility on the emission from a single nanocrystal quantum dot, exhibiting single photon purities exceeding 99.5%, without a significant loss of single photon efficiency. These methods can be applied for any indeterministic source of spectrally broadband photon pairs.