Gaussification and entanglement distillation of continuous variable systems: a unifying picture

TL;DR

This paper presents a unifying framework for Gaussianization and entanglement distillation in continuous variable quantum systems, introducing new protocols that balance success probability and entanglement enhancement.

Contribution

It introduces a general approach based on a non-commutative central limit theorem, unifying existing protocols and proposing new multipartite distillation methods.

Findings

Protocols converge to Gaussian states under specific measurement outcomes

Non-Gaussian states can be deterministically Gaussianized while preserving second moments

New multipartite distillation protocols enable balancing success probability and entanglement

Abstract

Distillation of entanglement using only Gaussian operations is an important primitive in quantum communication, quantum repeater architectures, and distributed quantum computing. Existing distillation protocols for continuous degrees of freedom are only known to converge to a Gaussian state when measurements yield precisely the vacuum outcome. In sharp contrast, non-Gaussian states can be deterministically converted into Gaussian states while preserving their second moments, albeit by usually reducing their degree of entanglement. In this work - based on a novel instance of a non-commutative central limit theorem - we introduce a picture general enough to encompass the known protocols leading to Gaussian states, and new classes of protocols including multipartite distillation. This gives the experimental option of balancing the merits of success probability against entanglement produced.