Evolution and entanglement of Gaussian states in the parametric amplifier

TL;DR

This paper investigates the evolution and entanglement of two-mode Gaussian states in a parametric amplifier using tomographic methods, quantifies entanglement, and explores nonlocal correlations and Bell inequalities.

Contribution

It introduces a method to analyze Gaussian state evolution and entanglement in a parametric amplifier via tomographic representation and qubit portrait mapping.

Findings

Calculated von Neumann and linear entropies for entanglement measurement

Compared nonlocal correlations with qubit map of Gaussian states

Established Bell inequalities using homodyne detection

Abstract

The linear time-dependent constants of motion of the parametric amplifier are obtained and used to determine in the tomographic-probability representation the evolution of a general two-mode Gaussian state. By means of the discretization of the continuous variable density matrix, the von Neumann and linear entropies are calculated to measure the entanglement properties between the modes of the amplifier. The obtained results for the nonlocal correlations are compared with those associated to a linear map of discretized symplectic Gaussian-state tomogram onto a qubit tomogram. This qubit portrait procedure is used to establish Bell-type's inequalities, which provide a necessary condition to determine the separability of quantum states, which can be evaluated through homodyne detection. Other no-signaling nonlocal correlations are defined through the portrait procedure for noncomposite systems.