Systematic entanglement concentration for unknown less-entangled three-photon W states

TL;DR

This paper introduces a systematic entanglement concentration protocol for unknown three-photon W states using quantum-dot spins in microcavities, improving success probability through iteration for quantum communication.

Contribution

It presents a novel entanglement concentration method for unknown three-photon W states utilizing optical properties of quantum-dot spins, with iterative enhancement of success probability.

Findings

Success probability is significantly increased by iterative process.

Protocol works with unknown coefficients in the W state.

Applicable to quantum communication networks.

Abstract

We present a systematic entanglement concentration protocol (ECP) for an arbitrary unknown less-entangled three-photon W state, resorting to the optical property of the quantum-dot spins inside one-sided optical microcavities. In our ECP, the parties obtain not only some three-photon systems in the partially entangled with two unknown parameters when one of the parties picks up the robust odd-parity instance with the parity-check gate (PCG) on his two photons, but also some entangled two-photon systems by keeping the even-parity instance in the first step. By exploiting the above three-photon and two-photon systems with the same parameters as the resource for the second step of our ECP, the parties can obtain a standard three-photon W state by keeping the robust odd-parity instance. Meanwhile, the systems in the even-parity instance can be used as the resource in the next round of our ECP. The success probability of our ECP is largely increased by iteration of the ECP process. As it does require that all the coefficients are unknown for the parties, our ECP maybe have good applications in quantum communication network in future.