Distillation and purification of symmetric entangled Gaussian states

TL;DR

This paper introduces a novel entanglement distillation protocol for symmetric Gaussian states that uses a two-copy de-Gaussification process with non-Gaussian filters to asymptotically produce pure entangled states.

Contribution

It extends existing protocols by incorporating a two-copy de-Gaussification method with non-Gaussian filtering using a Mach-Zehnder interferometer.

Findings

Achieves asymptotic extraction of pure entangled Gaussian states.

Utilizes a practical implementation involving single-photon addition and subtraction.

Enhances entanglement purification efficiency for symmetric Gaussian states.

Abstract

We propose an entanglement distillation and purification scheme for symmetric two-mode entangled Gaussian states that allows to asymptotically extract a pure entangled Gaussian state from any input entangled symmetric Gaussian state. The proposed scheme is a modified and extended version of the entanglement distillation protocol originally developed by [Browne et al., Phys. Rev. A 67, 062320 (2003)]. A key feature of the present protocol is that it utilizes a two-copy de-Gaussification procedure that involves a Mach-Zehnder interferometer with single-mode non-Gaussian filters inserted in its two arms. The required non-Gaussian filtering operations can be implemented by coherently combining two sequences of single-photon addition and subtraction operations.