Quantum and classical separability of spin-orbit laser modes

TL;DR

This paper explores the quantum and classical properties of spin-orbit laser modes, focusing on their entanglement and separability through an intensity-based CHSH inequality, highlighting the roles of coherence and photon number squeezing.

Contribution

It introduces a framework for characterizing spin-orbit entanglement using intensity fluctuations and coherence, linking classical and quantum inseparability criteria.

Findings

Violation of CHSH inequality indicates inseparability.

Quantum entanglement requires coherence and photon number squeezing.

Classical and quantum inseparability are distinguished by photon fluctuations.

Abstract

In this work we investigate the quantum noise properties of polarization vortices in connection with an intensity based Clauser-Horne-Shimony-Holt inequality for their spin-orbit separability. We evaluate the inequality for different input quantum states and the corresponding intensity fluctuations. The roles played by coherence and photon number squeezing provide a suitable framework for characterizing pure state spin-orbit entanglement. Structural inseparability of the spin-orbit mode requires coherence, an issue concerning either classical or quantum descriptions. In both cases, it can be witnessed by violation of this intensity based CHSH inequality. However, in the quantum domain, entanglement requires both coherence and reduced photon number fluctuations.