Nonclassicality and entanglement criteria for bipartite optical fields characterized by quadratic detectors

TL;DR

This paper derives and compares various inequalities based on moments and distributions of photocounts to identify nonclassicality and entanglement in bipartite optical fields, validated with experimental data from a twin beam.

Contribution

It introduces a set of ten inequalities for entanglement detection in bipartite optical fields and compares different theoretical approaches for deriving such inequalities.

Findings

Derived multiple inequalities for nonclassicality and entanglement detection.

Compared the performance of inequalities using experimental photocount data.

Proposed a basic set of inequalities suitable for monitoring entanglement in twin beams.

Abstract

Numerous inequalities involving moments of integrated intensities and revealing nonclassicality and entanglement in bipartite optical fields are derived using the majorization theory, non-negative polynomials, the matrix approach, as well as the Cauchy-Schwarz inequality. Different approaches for deriving these inequalities are compared. Using the experimental photocount histogram generated by a weak noisy twin beam monitored by a photon-number-resolving iCCD camera the performance of the derived inequalities is compared. A basic set of ten inequalities suitable for monitoring the entanglement of a twin beam is suggested. Inequalities involving moments of photocounts (photon numbers) as well as those containing directly the elements of photocount (photon-number) distributions are also discussed as a tool for revealing nonclassicality.