Efficient hybrid entanglement concentration for quantum communications

TL;DR

This paper introduces practical hybrid entanglement concentration protocols for optical quantum states, improving yield and feasibility for current quantum communication systems.

Contribution

It proposes two groups of ECPs, one requiring knowledge of initial coefficients and one not, with the second group achieving higher yield and some protocols being experimentally feasible.

Findings

Second group of protocols has higher yield than the first

Some protocols are based on linear optics and are experimentally feasible

Protocols do not always require knowledge of initial coefficients

Abstract

We present two groups of practical entanglement concentration protocols (ECPs) for optical hybrid entangled state (HES). In the first group, it contains two ECPs and both ECPs do not need to know the initial coefficients of the less-entangled state. The second group contains three ECPs and they need to know the initial coefficients. It is shown that the yield of the entanglement concentration in the second group is greater than the first group. Moreover, some protocols are based on the linear optics and can be easily realized under current experiment condition. These protocols may be useful in current hybrid quantum communication.