Ricerc@Sapienza

The ability to generate entangled photons states on demand is an essential resource for scaling up the complexity of the current quantum communication technologies. Epitaxial quantum dots have emerged as a leading candidate for overcoming the limit of probabilistic photon generation. Thanks to this advantage, their use is being pushed in an increasing number of applications. However, the potential of this technology has yet to be fully exploited.
The objective of this project is to experimentally investigate the possibility of generating different entangled states by exciting different charge complexes in semiconductor quantum dots. Entangled photons are usually generated in a specific polarization-entangled state via the mechanism of the ground biexciton-exciton radiative cascade. However, theoretical and experimental studies have shown that different spin complexes can be created inside a quantum dot, a resource which in principle could be harnessed to generate different entangled states. This could be used to actively switch operation mode and increase the functionalities of the source.
A combination of state-of-the-art skills and know-how in the fields of materials science and quantum optics will be crucial to tackle the challenges of this project. Based on the current state of research, GaAs/AlGaAs nanostructures grown by droplet etching epitaxy are selected as the entangled photon emitters. An experimental apparatus will be set up to spectrally isolate specific emission lines corresponding to different excitonic complexes and to investigate the presence and quality of entanglement in polarization via two-photon quantum state tomography.