On-chip engineering of frequency quantum states of light for quantum information

The exploitation and manipulation of quantum states of light play a key role in the development of quantum technologies. Photons exhibit quantum behaviour at room temperature, are resistant to noise and decoherence and offer many degrees of freedom, making them a promising platform in all the areas of quantum technologies: quantum communication, computing, simulation, and metrology. In this framework, integrated photonics plays a central role through the development of on-chip systems and many progresses in a wide variety of platforms have been reported in these last 2 decades. The elements required for any experimental setup can be divided in three main categories: generation of photons, their manipulation and their detection. My internship work focuses on an AlGaAs waveguide source of photon pairs, and in particular on the spectral narrowing of the emitted biphoton state by increasing the facet reflectivity through the deposition of Bragg mirrors, in view of a project of the team focused on the realization of an ion-photon interface. After performing numerical simulations to assess the impact of the mirror deposition on the biphoton state, I fabricated a sample by UV lithography and wet etching and characterized it via the Fabry-Pérot method. I repeated the characterization after the deposition of 3 SiO2/TiO2 Bragg mirrors. Finally, the experimental setup for the photon pair generation was mounted and tested; it will be used in future to characterize the conversion efficiency of my sample through HOM interference and JSI reconstruction.