# Preparation of bipartite bound entangled Gaussian states in quantum optics

## TL;DR

This paper introduces a parametrization of bipartite bound entangled Gaussian states in continuous-variable quantum systems and proposes an experimental protocol for their preparation in quantum optics, analyzing robustness under various conditions.

## Contribution

It provides a new parametrization of bound entangled Gaussian states and an experimental protocol for their preparation in quantum optics, including robustness analysis.

## Key findings

- Parametrization of a class of $2\times 2$ bound entangled Gaussian states.
- An experimental protocol for preparing bound entangled states.
- Robustness of the protocol against thermal noise and squeezing degrees.

## Abstract

The positivity of the partial transpose is in general only a necessary condition for separability. There exist quantum states that are not separable, but nevertheless are positive under partial transpose. States of this type are known as bound entangled states meaning that these states are entangled but they do not allow distillation of pure entanglement by means of local operations and classical communication (LOCC). We present a parametrization of a class of $2\times 2$ bound entangled Gaussian states for bipartite continuous-variable quantum systems with two modes on each side. We propose an experimental protocol for preparing a particular bound entangled state in quantum optics. We then discuss the robustness properties of this protocol with respect to the occupation number of thermal inputs and the degrees of squeezing.