Genuine Multipartite Entanglement without Multipartite Correlations

TL;DR

This paper introduces a method to construct and experimentally realize genuinely multipartite entangled states that lack n-partite correlations but still violate Bell inequalities, challenging classical correlation assumptions.

Contribution

It presents a general construction principle for such states, demonstrates their experimental realization, and analyzes their properties in detail.

Findings

States without n-partite correlations can still be genuinely entangled.

These states violate Bell inequalities despite lacking n-partite correlations.

The work challenges the classical understanding of correlations in quantum systems.

Abstract

Non-classical correlations between measurement results make entanglement the essence of quantum physics and the main resource for quantum information applications. Surprisingly, there are $n$-particle states which do not exhibit $n$-partite correlations at all but still are genuinely $n$-partite entangled. We introduce a general construction principle for such states, implement them in a multiphoton experiment and analyze their properties in detail. Remarkably, even without $n$-partite correlations, these states do violate Bell inequalities showing that there is no classical, i.e., local realistic model describing their properties.