Current-injection quantum-entangled-pair emitter using droplet epitaxial quantum dots on GaAs(111)A

A source of single photons and quantum entangled photon pairs is a key element in quantum information networks. Here, we demonstrate the electrically driven generation of quantum entangled pairs using a naturally symmetric GaAs quantum dot grown by droplet epitaxy. Coincidence histograms obtained at a temperature of 10 K reveal the generation of quantum entangled pairs that have a fidelity to the Bell pairs of 0.71 +- 0.015, much beyond the classical limit. The quantum nature of the emitted pairs is conserved at temperatures of up to ~65 K, and is essentially limited by the charge carrier confinement in the present dot system. Our study offers a guideline for the fabrication of quantum entangled pair sources suitable for practical use.