Observation of genuine one-way Einstein-Podolsky-Rosen steering

TL;DR

This paper experimentally demonstrates the existence of genuine one-way Einstein-Podolsky-Rosen steering in a broad measurement setting, confirming a fundamental asymmetry in quantum correlations with implications for quantum communication.

Contribution

It provides the first experimental observation of genuine one-way EPR steering for general measurement types, extending previous Gaussian-only results.

Findings

Confirmed one-way steerability in a practical entangled state

Demonstrated asymmetry in quantum nonlocality beyond Gaussian measurements

Implications for trust distribution in quantum networks

Abstract

Within the hierarchy of inseparable quantum correlations, Einstein-Podolsky-Rosen steering is distinguished from both entanglement and Bell nonlocality by its asymmetry -- there exist conditions where the steering phenomenon changes from being observable to not observable, simply by exchanging the role of the two measuring parties. Whilst this one-way steering feature has been previously demonstrated for the restricted class of Gaussian measurements, for the general case of positive-operator-valued measures even its theoretical existence has only recently been settled. Here, we prove, and then experimentally observe, the one-way steerability of an experimentally practical class of entangled states in this general setting. As well as its foundational significance, the demonstration of fundamentally asymmetric nonlocality also has practical implications for the distribution of the trust in quantum communication networks.