Using Separable Bell-Diagonal States to Distribute Entanglement

TL;DR

This paper investigates how Bell-diagonal states can be used to distribute entanglement between parties, identifying key conditions and bounds that determine the effectiveness of this process.

Contribution

It provides necessary and sufficient conditions for Bell-diagonal states to serve as resources for entanglement distribution, along with bounds on the amount of entanglement achievable.

Findings

Conditions for Bell-diagonal states to distribute entanglement

Upper and lower bounds on distributed entanglement

Insights into resource properties enabling entanglement transfer

Abstract

One of the many bizarre features of entanglement is that Alice, by sending a qubit to Bob in a separable state, can generate some entanglement between herself and Bob. This protocol is stripped down to the bare essentials to better elucidate the key properties of the initial resource state that enable this entanglement distribution. The necessary and sufficient conditions under which the correlations of a Bell-diagonal state serve as a useful resource are proven, giving upper and lower bounds on the entanglement that can be distributed when those conditions are met.