DOCTORAL CANDIDATE
Enrico Maria Valentini

SUPERVISORS
Kamel Bencheikh, Centre National de la Recherche Scientifique – C2N (CNRS – C2N)
Arnan Mitchell, RMIT University (RMIT)

Quantum optics, Non-linear Optics, Integrated Photonics, Quantum mechanics, Nanofabrication

The generation and the manipulation of quantum states of light is a fundamental issue for quantum information. Among these states, twin-photon states whose quantum entanglement and quantum superposition allowed exciting and breakthrough demonstrations in the field of quantum information. Over the last years, a new platform for the generation of twin-photon states has emerged. It is based on thin film lithium niobate on insulator (LNOI), a material widely used by the quantum and nonlinear community for its large nonlinear coefficients. On this platform, lithium niobate thickness is below 1 µm and the advances in nanotechnology fabrications allow reduced-size waveguides in which optical modes with cross sections less than 1 µm2 can propagate. On this new platform, we can design sophisticated integrated circuits, compatible with telecom band, to generate nonclassical states of light and manipulate their quantum properties with high efficiencies due the high nonlinearities obtained thanks to the tight optical confinement. The nanofabrication of the waveguides on this LNOI platform is done at RMIT University.

The thesis project objective is to explore the generation and manipulation of quantum states on this new platform at the single photon level. The quantum states will be generated through spontaneous parametric generation, where a pump photon at 780 nm is converted into twin photons at 1560 nm, called “signal” and “idler”. The aim is to demonstrate the quantum entanglement of the generated twin photons and use this remarkable property for entanglement swapping, where two independent photons generated in separate waveguides become entangled after a Bell-like quantum measurement. The required architecture of the LNOI waveguides will be designed and fabricated during the project and an experimental setup dedicated to the quantum demonstrations will be set. For the demonstration, two independent periodically poled LNOI waveguides will be fabricated on a same chip to generated twin photons. The LNOI chip will as well include a tunable integrated beam-splitter to mix the two “signal” modes for the Bell-State projection and measurement. Extra building blocks will be added to root, select, and shape the different optical modes.

The project will be performed in collaboration between the primary institutions C2N and RMIT and associated collaboration with Adelaide, gathering their expertise in nonlinear and quantum optics, nanophotonic and LNOI nanotechnology.