Requirements for two-source entanglement concentration

TL;DR

This paper analyzes the role of Gaussian and non-Gaussian measurements in entanglement concentration for two-mode squeezed vacua, identifying strict conditions for successful entanglement enhancement using joint measurements.

Contribution

It provides a detailed analysis of measurement requirements for entanglement concentration on two-source quantum states, extending previous experimental approaches.

Findings

Stringent measurement conditions are necessary for entanglement improvement.

Joint measurements on two resource states are crucial for effective entanglement concentration.

The study clarifies the limitations of current measurement strategies for entanglement enhancement.

Abstract

Entanglement enhancement is a key task for quantum technologies. This operation performed on states produced by parametric down-conversion sources has been the object of several recent experimental investigations. In particular, conditional preparation by photon-subtraction has been shown to improve the entanglement of these states. Here we analyse the role played by non-Gaussian and Gaussian measurements in more general entanglement concentration operations performed on a pair of two-mode squeezed vacua. We find stringent requirements for achieving an improved entanglement enhancement by measuring jointly these two resource states.