Entangler and analyzer for multiphoton maximally entangled states using weak nonlinearities

TL;DR

This paper proposes feasible schemes using weak nonlinearities for generating and analyzing multiphoton maximally entangled states, including nearly deterministic GHZ state generation and discrimination, advancing quantum information processing capabilities.

Contribution

It introduces new schemes for entangling and analyzing multiphoton entangled states using weak nonlinearities, with high efficiency and near-deterministic performance.

Findings

Nearly deterministic generation of GHZ and Bell states.

High-efficiency discrimination of all GHZ states.

Design of a nondestructive Bell-state analyzer.

Abstract

In the regime of weak nonlinearity we present two general feasible schemes. One is an entangler for generating any one of the $n$-photon Greenberger-Horne-Zeilinge (GHZ) states and Bell states. After the interactions with cross-Kerr nonlinear media, a phase gate followed by a measurement on the probe beam, and appropriate local operations via classical feed-forward, one can obtain the desired states in a nearly deterministic way. Another scheme is an analyzer for multiphoton maximally entangled states, which is taken as a further application of the above entangler. In this scheme, all of the $2^n$ $n$-photon GHZ states can, nearly deterministically, be discriminated. Furthermore, an efficient two-step nondestructive Bell-state analyzer is designed.