Quantum light states in integrated lithium niobate nanoscale platforms

This project aims to integrate quantum light sources into photonic platforms based on commercially available lithium niobate (LiNbO₃) thin films, in alignment with the dual objectives of the A3 NQSTI call. The first objective is the development of hybrid platforms that combine deterministic single-photon sources with monolithic LiNbO₃ devices, while the second focuses on the realization of nanoscale LiNbO₃-based sources of entangled photons through spontaneous parametric down-conversion (SPDC) operating in the telecommunication window.

Central to both goals is the enhancement of light–matter interactions at the nanoscale, particularly in configurations where the excitation wavelength differs from the emission wavelength. To achieve this, the project explores doubly resonant geometries capable of sustaining sharp electromagnetic modes at both excitation and emission frequencies, thereby enabling efficient and tunable quantum light generation.

The research involves the design and realization of doubly resonant LiNbO₃ nanoantennas and metasurfaces tailored for free-space applications, including emerging fields such as space-based quantum communication. In parallel, optimized device architectures will be monolithically integrated onto LiNbO₃ waveguides to enable seamless in-coupling and out-coupling of quantum light states, as well as on-chip photon antibunching and correlation measurements within the same LiNbO₃ platform.

Fabrication of these advanced devices will be carried out using the state-of-the-art nanofabrication facilities at Polifab, the technological hub of Politecnico di Milano. These resources provide the precision, control, and reproducibility necessary to realize a next-generation quantum photonic platform that merges fundamental quantum optics with scalable, integrated technology.