A Pure and indistinguishable single-photon source at telecommunication wavelength

TL;DR

This paper demonstrates a quantum frequency conversion scheme that transforms single photons from quantum dots to the telecommunication band at 1550 nm, maintaining high purity and indistinguishability, crucial for fiber-based quantum networks.

Contribution

It introduces a novel frequency conversion method that preserves photon quality during wavelength translation for quantum dot sources.

Findings

Achieved 40.8% end-to-end efficiency in frequency conversion.

Maintained high photon purity with $g^{(2)}(0)=2.4\\%$ after conversion.

Preserved high indistinguishability with $V^{\\text{corr}}=94.8\\%$.

Abstract

On-demand single-photon sources emitting pure and indistinguishable photons at the telecommunication wavelength are a critical asset towards the deployment of fiber-based quantum networks. Indeed, single photons may serve as flying qubits, allowing communication of quantum information over long distances. Self-assembled InAs quantum dots embedded in GaAs constitute an excellent nearly deterministic source of high quality single photons, but the vast majority of sources operate in the 900-950 nm wavelength range, precluding their adoption in a quantum network. Here, we present a quantum frequency conversion scheme for converting single photons from quantum dots to the telecommunication C band, around 1550 nm, achieving 40.8% end-to-end efficiency, while maintaining both high purity and a high degree of indistinguishability during conversion with measured values of $g^{(2)}(0)=2.4\%$ and $V^{\text{corr}}=94.8\%$, respectively.