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 halfway 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.

Automated summary

We analyze and compare three quantum communication protocols proposed in the literature for their ability to transmit single-rail entanglement. Specific metrics are used to measure output-state purity and probability of success, taking into account the imperfections of photon source and detection components. Our findings suggest that, under most conditions, a distributed noiseless linear amplification (NLA) protocol with a relay point placed halfway between Alice and Bob outperforms NLA at Bob's end and a recently proposed purification protocol, unless the distance is very small or the photon source component is of high quality.