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

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 microlens-enhanced devices in conjunction with their substantial brightness, raw entanglement fidelities of up to 0.95 +/- 0.01 and postselected photon indistinguishabilities of up to 0.93 +/- 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 facilitate an innovative method to determine the extraction and excitation efficiencies directly, as opposed to commonly employed indirect techniques. Additionally, time-resolved analysis of Hong-Ou-Mandel interference traces reveal an alternative approach to the investigation of pure photon dephasing.