Bounouar, SamirHaye, Christpoh de laStrauß, MaxSchnauber, PeterThoma, AlexanderGschrey, ManuelSchulze, Jan-HindrikStrittmatter, AndréRodt, SvenReitzenstein, Stephan2020-02-172020-02-172018-04-120003-6951https://depositonce.tu-berlin.de/handle/11303/10730http://dx.doi.org/10.14279/depositonce-9627This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 112, 153107 (2018) and may be found at https://doi.org/10.1063/1.5020242.The integration of entangled photon emitters in nanophotonic structures designed for the broadband enhancement of photon extraction is a major challenge for quantum information technologies. We study the potential of quantum dot (QD) microlenses as efficient emitters of maximally entangled photons. For this purpose, we perform quantum tomography measurements on InGaAs QDs integrated deterministically into microlenses. Even though the studied QDs show non-zero excitonic fine-structure splitting (FSS), polarization entanglement can be prepared with a fidelity close to unity. The quality of the measured entanglement is only dependent on the temporal resolution of the applied single-photon detectors compared to the period of the excitonic phase precession imposed by the FSS. Interestingly, entanglement is kept along the full excitonic wave-packet and is not affected by decoherence. Furthermore, coherent control of the upper biexcitonic state is demonstrated.en530 Physikbiexcitonsintegrated opticslight polarisationmicrolensesnanophotonicsquantum entanglementquantum opticssemiconductor quantum dotsArticle1077-3118