# Linear optics based entanglement concentration protocols for Cluster-type entangled coherent state

## TL;DR

This paper introduces two linear optics-based entanglement concentration protocols to convert partially entangled cluster-type entangled coherent states into maximally entangled states, with potential applications in long-distance quantum communication.

## Contribution

The paper presents two novel linear optics-based protocols for entanglement concentration of cluster-type ECS, including success probabilities and quantum circuits for experimental realization.

## Key findings

- Success probabilities calculated for both protocols
- Quantum circuits provided for experimental implementation
- Protocols beneficial for long-distance quantum communication

## Abstract

We proposed two linear optics based entanglement concentration protocols (ECPs) to obtain maximally entangled 4-mode Cluster-type entangled coherent state (ECS) from less (partially) entangled Cluster-type ECS. The first ECP is designed using a superposition of single-mode coherent state with two unknown parameters, whereas the second ECP is obtained using a superposition of single-mode coherent state and a superposition of two-mode coherent state with four unknown parameters. The success probabilities have been calculated for both the ECPs. Necessary quantum circuits enabling future experimental realizations of the proposed ECPs are provided using linear optical elements. Further, the benefit of the proposed schemes is established in the context of long distance quantum communication where photon loss is an obstruction.