Continuous-variables entanglement purification with atomic systems

TL;DR

This paper proposes a method for purifying entanglement in continuous-variable quantum states of optical fields using atomic ensembles and non-Gaussian measurements, advancing quantum communication networks.

Contribution

It introduces a novel entanglement purification scheme utilizing atomic ensembles and dichotomic measurements for continuous-variable systems.

Findings

Effective entanglement purification demonstrated

Scheme applicable to quantum networks and repeaters

Utilizes non-Gaussian measurement for improved performance

Abstract

We present a proposal for entanglement purification of the continuous-variable quantum state of two propagating optical fields. The scheme is based on letting each field interact with a local node, an atomic ensemble, whose internal collective excitation plays the role of an ancillary continuous variable resource. Entanglement purification is achieved by a dichotomic measurement, representing the required non-Gaussian element, and which consists in detecting the presence or absence of collective excitations in the atomic ensemble. This scheme can be extended to networks, where the nodes are single trapped atoms, and constitutes an important building block for the implementation of a continuous-variable quantum repeater.