Large-scale multipartite entanglement in the quantum optical frequency comb of a depleted-pump optical parametric oscillator

TL;DR

This paper theoretically demonstrates that a single optical parametric oscillator can generate large-scale multipartite entanglement across its optical frequency comb, driven by the strongly depleted pump field, surpassing previous undepleted pump models.

Contribution

It introduces a theoretical model showing how pump depletion induces massive multipartite entanglement in the frequency comb of an OPO, a novel insight into quantum correlations in such systems.

Findings

Multipartite entanglement is generated across the frequency spectrum of a single OPO.

Pump depletion plays a crucial role in the emergence of entanglement.

The entanglement is verified using the van Loock-Furusawa criterion.

Abstract

We show theoretically that multipartite entanglement is generated on a massive scale in the spectrum, or optical frequency comb, of a single optical parametric oscillator (OPO) emitting well above threshold. In this system, the quantum dynamics of the strongly depleted pump field are responsible for the onset of the entanglement by correlating the two-mode squeezed, bipartite-entangled pairs of OPO signal fields. (Such pairs are independent of one another in the undepleted, classical pump approximation.) We verify the multipartite nature of the entanglement by evaluating the van Loock-Furusawa criterion for a particular set of entanglement witnesses deduced from physical considerations.