Preparation and purification of four-photon Greenberger-Horne-Zeilinger state

TL;DR

This paper introduces an efficient linear optics-based method for creating and purifying four-photon GHZ states, capable of handling noise and using photon detection to confirm successful state generation.

Contribution

It presents a novel scheme combining creation and purification of four-photon GHZ states using linear optics and postselection, including noise resistance and photon detection techniques.

Findings

Successful creation of four-photon GHZ states from two pairs.

Effective purification of GHZ states under depolarization noise.

Detection scheme using fourfold coincidence confirms state generation.

Abstract

We present an efficient scheme for preparing and purifying of four-photon Greenberger-Horne-Zeilinger (GHZ) state based on linear optics and postselection. First, we describe how to create a four-photon GHZ state in both polarization and spatial degrees of freedom from two pairs. Moreover, in the presence of depolarization noise our scheme is capable of purifying the desired state. In the regime of weak nonlinearity we design an indirect photon number-resolving detection to distinguish two states of the two pairs. At last, a fourfold coincidence detector click indicates creating of a polarization-entangled four-photon GHZ state.