Post-selected entanglement from GaAs quantum dots

Bright, high-purity sources of entangled photons are critical for efficient quantum communication, quantum sensing, and quantum computing. Entanglement sources leveraging spontaneous parametric down-conversion (SPDC) been prominent in the field, but are limited by their probabilistic nature and the possibility of multi-pair events which. By starting with high purity single photons (g⁽²⁾(0)=2.5%) from GaAs quantum dots, we demonstrate an entanglement source that has the potential to outperform SPDC for applications such as entanglement swapping within long-range quantum networks. We alternate the polarization of and delay every other photon, overlapping them on a non-polarizing beam splitter. For the cases where the photons exit different ports of the beamsplitter, we report post-selected entanglement in the state ψ=HV+VH, with a singlet fraction exceeding 96%.