Optimal entanglement manipulation via coherent-state transmission

TL;DR

This paper establishes the optimal bounds for entanglement manipulation using coherent-state transmission over lossy channels and introduces a protocol that surpasses existing schemes, leveraging beam splitters and QND measurements.

Contribution

It derives the fundamental limits of entanglement manipulation via coherent states and proposes an optimal protocol that outperforms previous methods.

Findings

The protocol outperforms known entanglement generation schemes.

Optimal bounds are derived for entanglement manipulation with coherent states.

The protocol remains effective even with photon detectors replacing QND measurements.

Abstract

We derive an optimal bound for arbitrary entanglement manipulation based on the transmission of a pulse in coherent states over a lossy channel followed by local operations and unlimited classical communication (LOCC). This stands on a theorem to reduce LOCC via a local unital qubit channel to local filtering. We also present an optimal protocol based on beam splitters and a quantum nondemolition (QND) measurement on photons. Even if we replace the QND measurement with photon detectors, the protocol outperforms known entanglement generation schemes.