Novel bulk architecture for entangled two-photons source

Polarization-entangled photon sources (EPS) are an important enabling technology in the fields of quantum sensing, quantum communication, and quantum computing. Recently, a need has arisen for efficient sources of entangled photons with high brightness and phase stability, for use in free space and fiber-based communication links. In the proposed thesis activity, a prototype of EPS based on commercial bulk opto-mechanical components will be developed and characterized. The system is based on type-0 collinear spontaneous parametric down-conversion (SPDC), which will be realized via quasi-phase matching in periodically poled KTiOPO 4  (PPKTP). The emission can be prepared as an N00N state for sensing or as a Bell state for entanglement-based quantum key distribution (QKD) protocols. The testing on the EPS prototype attained a maximal Bell inequality violation with >99% average entanglement visibility. We discuss and demonstrate innovative methods to improve the EPS's heralding rate while further applications and optimizations are proposed.