Device-independent entanglement quantification and related applications

TL;DR

This paper introduces a general, device-independent method to quantify bipartite and multipartite entanglement based solely on observed data, providing tight bounds and applications like dimension witnesses and entanglement witnesses.

Contribution

The authors develop a universal approach for device-independent entanglement quantification that is applicable to both bipartite and multipartite systems, with tight bounds for key inequalities.

Findings

Tight bounds for CHSH and Svetlichny inequalities.

Method enables construction of dimension witnesses.

Provides insights into Bell inequality violations by bound entangled states.

Abstract

We present a general method to quantify both bipartite and multipartite entanglement in a device-independent manner, meaning that we put a lower bound on the amount of entanglement present in a system based on observed data only but independently of any quantum description of the employed devices. Some of the bounds we obtain, such as for the Clauser-Horne-Shimony-Holt Bell inequality or the Svetlichny inequality, are shown to be tight. Besides, device-independent entanglement quantification can serve as a basis for numerous tasks. We show in particular that our method provides a rigorous way to construct dimension witnesses, gives new insights into the question whether bound entangled states can violate a Bell inequality, and can be used to construct device independent entanglement witnesses involving an arbitrary number of parties.