Non-Gaussian entanglement revealed by higher-order quadrature cumulants

TL;DR

This paper introduces a new method using higher-order quadrature cumulants to detect non-Gaussian entanglement, demonstrated experimentally with photon-subtracted squeezed states, enabling advanced quantum information processing.

Contribution

It develops a framework for detecting non-Gaussian entanglement via higher-order cumulants, surpassing Gaussian criteria and demonstrating practical advantages in quantum teleportation.

Findings

Higher-order cumulants reveal entanglement missed by Gaussian criteria.

Experimental certification of non-Gaussian entanglement in photon-subtracted states.

Enhanced quantum teleportation of Wigner negativity using non-Gaussian resources.

Abstract

Entanglement is central to quantum physics, yet detecting and exploiting it in non-Gaussian systems remains a major challenge. In continuous variable platforms, standard inseparability criteria based on Gaussian statistics-such as the Duan-Simon criterion-fail when quantum correlations are encoded in higher moments of the field quadratures. Here we introduce a framework for detecting non-Gaussian entanglement using higher-order quadrature cumulants. In the Gaussian limit, the lowest order condition reduces to the Duan criterion, while higher-order violations reveal entanglement inaccessible to second-order methods. We experimentally demonstrate a tomography-free certification of inseparability in photon-subtracted squeezed states of light, where Gaussian witnesses fail despite the presence of entanglement. We further show that such higher-order inseparability enables enhanced quantum teleportation of Wigner negativity as compared to Gaussian protocols. These results identify higher-order cumulants as natural observables for non-Gaussian entanglement and open new routes to harnessing non-Gaussian resources in continuous variable quantum technologies.