Comparison of Techniques for Distillation of Entanglement over a Lossy Channel

We analyze three quantum communication protocols that have been proposed in the literature, and compare how well they communicate single-rail entanglement. We use specific metrics for output state purity and probability of success and include the presence of imperfect photon source and detection components. We find that a distributed noiseless linear amplification (NLA) protocol with a relay point placed half-way between Alice and Bob outperforms NLA at Bob’s end and a recently proposed purification protocol under most conditions, unless the distance is very small or the photon source component is very good.