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An operational framework for nonlocality
Rodrigo Gallego, Lars E. Würflinger, Antonio Acín, Miguel Navascués
TL;DR
The paper seeks an operational framework for nonlocality as a resource comparable to entanglement. It defines WCCPI operations, shows that Svetlichny’s standard multipartite definition is inconsistent because collaboration can generate nonlocality, and discusses consistent alternatives.
Problem
Nonlocality needs an operational framework for characterization and quantification as a resource, analogous to entanglement.
Method
The paper defines nonlocality through Wirings and Classical Communication Prior to the Inputs (WCCPI), under which nonlocality cannot be created.
Results
The standard bilocal definition of genuine multipartite nonlocality is inconsistent because WCCPI collaboration can map bilocal correlations into Bell-nonlocal correlations.
Takeaways & Limitations
Alternative definitions, including no-signalling bilocal and time-ordered bilocal correlations, recover consistency with the operational framework.
Takeaways & Limitations
The largest correlation set consistent under WCCPI remains an open question, although the paper conjectures that TOBL correlations provide it.
Abstract
from arXiv · showhide
Due to the importance of entanglement for quantum information purposes, a framework has been developed for its characterization and quantification as a resource based on the following operational principle: entanglement among $N$ parties cannot be created by local operations and classical communication, even when $N-1$ parties collaborate. More recently, nonlocality has been identified as another resource, alternative to entanglement and necessary for device-independent quantum information protocols. We introduce an operational framework for nonlocality based on a similar principle: nonlocality among $N$ parties cannot be created by local operations and allowed classical communication even when $N-1$ parties collaborate. We then show that the standard definition of multipartite nonlocality, due to Svetlichny, is inconsistent with this operational approach: according to it, genuine tripartite nonlocality could be created by two collaborating parties. We finally discuss alternative definitions for which consistency is recovered.