Maximally entangled and GHz-clocked on-demand photon pair source

TL;DR

This paper introduces a GHz-clocked, on-demand photon pair source using droplet etched GaAs quantum dots, achieving high entanglement fidelity and photon indistinguishability suitable for long-range quantum communication.

Contribution

It demonstrates a novel high-speed photon pair source with high entanglement fidelity and innovative methods for directly measuring key quantum optical parameters.

Findings

Raw entanglement fidelity up to 0.95

Photon indistinguishability up to 0.93

Suitable for quantum repeater schemes

Abstract

We present a 1 GHz-clocked, maximally entangled and on-demand photon pair source based on droplet etched GaAs quantum dots using two-photon excitation. By employing these GaP microlensenhanced devices in conjunction with their substantial brightness, raw entanglement fidelities of up to $0.95 \pm 0.01$ and post-selected photon indistinguishabilities of up to $0.93 \pm 0.01$, the suitability for quantum repeater based long range quantum entanglement distribution schemes is shown. Comprehensive investigations of a complete set of polarization selective two-photon correlations as well as time resolved Hong-Ou-Mandel interferences facilitate innovative methods that determine quantities such as photon extraction and excitation efficiencies as well as pure dephasing directly - opposed to commonly employed indirect techniques.