The quantum-classical transition in thermally seeded parametric downconversion

TL;DR

This paper investigates how thermal seeding influences the quantum-to-classical transition in parametric downconversion, analyzing correlations and entanglement, and demonstrating tunable thresholds unaffected by losses.

Contribution

It provides explicit criteria for nonclassicality thresholds in thermal-seeded parametric downconversion and shows how to control the quantum-classical transition via seed intensities.

Findings

Nonclassicality thresholds depend on thermal and downconversion photon numbers.

Transition from quantum to classical can be tuned by seed intensities.

Thresholds are unaffected by losses, only reducing nonclassicality.

Abstract

We address the pair of conjugated field modes obtained from parametric-downconversion as a convenient system to analyze the quantum-classical transition in the continuous variable regime. We explicitly evaluate intensity correlations, negativity and entanglement for the system in a thermal state and show that a hierarchy of nonclassicality thresholds naturally emerges in terms of thermal and downconversion photon number. We show that the transition from quantum to classical regime may be tuned by controlling the intensities of the seeds and detected by intensity measurements. Besides, we show that the thresholds are not affected by losses, which only modify the amount of nonclassicality. The multimode case is also analyzed in some detail.