In spite of the numerous delays in project activities due to the corona pandemic, the project output included: A nanopost single-photon source geometry with a measured extraction efficiency of 0.35 and a broadband Purcell enhancement of 5 was demonstrated in a joint effort led by CEA. A study on molecular beam epitaxy grown quantum dots with a contaminated aluminum evaporation cell was conducted by RUB and a way of addressing this problem to restore growth of excellent low noise heterostructures was identified. Optical driving of the radiative Auger transition in a trion of a semiconductor quantum dot was demonstrated linking few-body Coulomb interactions and quantum optics.
The project aimed at continuously producing and communicating progress results within optical quantum-dot based quantum technology, both to the scientific community and the wider audience. In particular, we achieved our project objectives of demonstrating the scalability of optical quantum information technology, through the demonstrations of unprecedented SPS and entangled-photon pair brightness, on-chip integration capability and optical gating with full control of the decoherence. As a highlight, new micropillar single-photon source structures with improved first lens brightness were obtained, with a measured record value of 55% efficiency. The sources were later used for the first quantum computing prototype demonstrations at QUA with 6 photons. While the scientific work performed remains of a fundamental research character and was severely impacted by the corona crisis, the output results have been published in prestigious journals including Nature Photonics, Nature Nanotechnology, and Nature Communications, Physical Review Letters, Nano Letters and ACS Photonics, and selected work was presented at international conferences including Quantum Information and Measurement VI, SPIE, CLEO and the APS.
