Arbitrary Partially Entangled Three-Electron W State Concentration with Controlled-Not Gates

Bin Gu, Yugai Huang, Xia Fang +1 more

Hong‐Fu Wang, Li-Li Sun, Shou Zhang +1 more

Sheng-Yang Zhao, Jiong Liu, Lan Zhou +1 more

Yu‐Bo Sheng, Zhao-Feng Feng, Yang Ou-Yang +2 more

We describe an efficient entanglement concentration protocol (ECP) for an arbitrary partially entangled three-electron W state. We show that with the help of two ancillary single electrons, the concentration task can be well completed. This ECP has several advantages: Firstly, we only require one pair of partially entangled states. Secondly, only two single electrons are used during the whole protocol. Thirdly, we do not require all the parties to participate in the whole process, and only two parties are needed to perform the operation. Fourthly, the protocol can be repeated to obtain a high success probability. This ECP may be useful in current quantum computation and quantum communication.

Chun Wang, Zhi Zeng, Xihan Li

Hong‐Fu Wang, Shou Zhang, Kyu-Hwang Yeon

We propose two experimental schemes for concentrating entanglement in unknown partially entangled three-photon W states with only linear optical elements and the conventional photon detectors. We first propose a heralded scheme using a heralded controlled-NOT (CNOT) gate between two photons. Then we simplify this method to a post-selected one requiring time entanglement of the input photons without using ancillary photons. In the two schemes, Alice, Bob, and Charlie at three distant parties can obtain one maximally entangled three-photon W state from two identical partially entangled three-photon W states, taking the specific form of α|H>|H>|V>+β(|H>|V>|H>+|V>|H>|H>), by local operations and classical communication. We discuss and consider the success probabilities and the practical realizations of the schemes.