Quadripartite continuous-variable entanglement via quadruply concurrent downconversion

TL;DR

This paper proposes a cavity-based scheme using concurrent nonlinearities to generate and verify quadripartite continuous-variable entanglement, providing analytical solutions and analyzing entanglement properties across different operational regimes.

Contribution

It introduces a novel intra-cavity coupled down-conversion method for quadripartite entanglement with analytical solutions and entanglement verification techniques.

Findings

Quadripartite entanglement verified via fluctuation spectra.

Violations of van Loock-Furusawa inequalities demonstrated.

Entanglement characteristics analyzed above and below threshold.

Abstract

We investigate an intra-cavity coupled down-conversion scheme to generate quadripartite entanglement using concurrently resonant nonlinearities. We verify that quadripartite entanglement is present in this system by calculating the output fluctuation spectra and then considering violations of optimized inequalities of the van Loock-Furusawa type. The entanglement characteristics both above and below the oscillation threshold are considered. We also present analytic solutions for the quadrature operators and the van Loock-Furusawa correlations in the undepleted pump approximation.