Experimental criteria for steering and the Einstein-Podolsky-Rosen paradox

TL;DR

This paper develops a comprehensive theoretical framework linking quantum steering criteria with EPR paradox demonstrations, unifying previous approaches and enhancing detection of quantum nonlocality across various states.

Contribution

It introduces a general theory of EPR-steering criteria applicable to both discrete and continuous variables, unifying and extending prior methods from a modern quantum-information perspective.

Findings

Derived new EPR-steering criteria for different observables

Unified previous EPR-type criteria within a single formalism

Analyzed effectiveness of criteria in detecting nonlocality

Abstract

We formally link the concept of steering (a concept created by Schrodinger but only recently formalised by Wiseman, Jones and Doherty [Phys. Rev. Lett. 98, 140402 (2007)] and the criteria for demonstrations of Einstein-Podolsky-Rosen (EPR) paradox introduced by Reid [Phys. Rev. A, 40, 913 (1989)]. We develop a general theory of experimental EPR-steering criteria, derive a number of criteria applicable to discrete as well as continuous-variables observables, and study their efficacy in detecting that form of nonlocality in some classes of quantum states. We show that previous versions of EPR-type criteria can be rederived within this formalism, thus unifying these efforts from a modern quantum-information perspective and clarifying their conceptual and formal origin. The theory follows in close analogy with criteria for other forms of quantum nonlocality (Bell-nonlocality, entanglement), and because it is a hybrid of those two, it may lead to insights into the relationship between the different forms of nonlocality and the criteria that are able to detect them.