Experimental GHZ Entanglement beyond Qubits

TL;DR

This paper reports the experimental generation of a three-dimensional GHZ entangled state from two-photon orbital-angular-momentum entanglement, enabling high-dimensional tests of quantum nonlocality beyond qubits.

Contribution

It demonstrates a novel method to produce three-dimensional GHZ states from entangled photon pairs, advancing high-dimensional quantum entanglement research.

Findings

Successful generation of 3D GHZ state from two-photon entanglement

First experimental realization of high-dimensional GHZ entanglement beyond qubits

Potential for high-dimensional tests of quantum nonlocality

Abstract

The Greenberger-Horne-Zeilinger (GHZ) argument provides an all-or-nothing contradiction between quantum mechanics and local-realistic theories. In its original formulation, GHZ investigated three and four particles entangled in two dimensions only. Very recently, higher dimensional contradictions especially in three dimensions and three particles have been discovered but it has remained unclear how to produce such states. In this article we experimentally show how to generate a three-dimensional GHZ state from two-photon orbital-angular-momentum entanglement. The first suggestion for a setup which generates three-dimensional GHZ entanglement from these entangled pairs came from using the computer algorithm Melvin. The procedure employs novel concepts significantly beyond the qubit case. Our experiment opens up the possibility of a truly high-dimensional test of the GHZ-contradiction which, interestingly, employs non-Hermitian operators.