Dottorato in FISICA

Titolo della tesi: High-dimensional photonics resources for quantum information processing and quantum networks

High-dimensional resources are fundamental for the development of quantum technologies from quantum computation, quantum cryptography and communication to quantum foundation. Therefore, the progress in methods to generate and manipulate them is crucial. In this thesis, we implemented photonic platforms realizing high-dimensional quantum states, applied to quantum information protocols and fundamental tests of quantum mechanics. In particular, we focused on two classes of high dimensional quantum states: those composed of a single qudit and those composed of n distinct qubits. On one side, encoding qudit states in the orbital angular momentum degree of freedom of single photons, we experimentally realize protocols of engineering and detection using also machine learning-based techniques. Explicitly, we employed the dynamics of a one-dimensional quantum walk to implement a platform-independent engineering protocol, whose performances have been further improved by exploiting an optimization algorithm to take into account experimental imperfections and noisy perturbations. Moreover, we focused on both proposing machine learning-based innovative techniques and improving the standard experimental platforms to efficiently detect OAM states. On the other side, distributing polarization-entangled states of photons in networks configurations, we proposed and realized a scalable experimental platform to implement networks of growing size and different topologies. We employed these networks to perform device-independent protocols and we detected their non-locality behaviors going beyond the standard bipartite Bell scenario. In particular, starting from a bipartite Bell scenario optimized in a fully black-box approach, we extended our investigation to the self-testing of multipartite entangled states in two- and three-node quantum networks, until reaching more complex networks as the star and the triangle configurations where new forms of non-locality arise.