Interplay of nonclassicality and entanglement of two-mode Gaussian fields generated in optical parametric processes

TL;DR

This paper investigates how nonclassicality and entanglement in two-mode Gaussian states interact and transform when passing through a beam splitter, revealing the global nonclassicality resource and predicting various nonclassical output states.

Contribution

It introduces quantifiers based on invariants of linear transformations to analyze the interplay of nonclassicality and entanglement in Gaussian states at a beam splitter.

Findings

Quantifiers derived from invariants effectively measure nonclassicality and entanglement.

Beam splitter transformations can convert local nonclassicality into entanglement and vice versa.

Rich nonclassical output states are predicted from various input configurations.

Abstract

The behavior of general nonclassical two-mode Gaussian states at a beam splitter is investigated. Single-mode nonclassicality as well as two-mode entanglement of both input and output states are analyzed suggesting their suitable quantifiers. These quantifiers are derived from local and global invariants of linear unitary two-mode transformations such that the sum of input (or output) local nonclassicality measures and entanglement measure gives a global invariant. This invariant quantifies the global nonclassicality resource. Mutual transformations of local nonclassicalities and entanglement induced by the beam splitter are analyzed considering incident noisy twin beams, single-mode noisy squeezed vacuum states, and states encompassing both squeezed states and twin beams. A rich tapestry of interesting nonclassical output states is predicted.