Hybrid photonic entanglement using a PPLN crystal

We propose a scheme to generate hybrid photonic entanglement, defined as entanglement between photonic qubits with different encodings, using quasi phase-matched parametric downconversion in a periodically-poled lithium niobate (PPLN) crystal. The hybrid entanglement is obtained by first generating two time-bin entangled qubits at 810 and 1550 nm. Then, using standard fibre telecom components, the 810~nm qubit is deterministically converted to a polarization qubit which can be transmitted in free-space. We report on our progress towards building and characterizing such a source and discuss its utility in creating hybrid quantum networks.