  Using only linear optical elements, the creation of dual-rail photonic
entangled states is inherently probabilistic. Known entanglement generation
schemes have low success probabilities, requiring large-scale multiplexing to
achieve near-deterministic operation of quantum information processing
protocols. In this paper, we introduce multiple techniques and methods to
generate photonic entangled states with high probability, which have the
potential to reduce the footprint of Linear Optical Quantum Computing (LOQC)
architectures drastically. Most notably, we are showing how to improve Bell
state preparation from four single photons to up to p=2/3, boost Type-I fusion
to 75% with a dual-rail Bell state ancilla and improve Type-II fusion beyond
the limits of Bell state discrimination.
