Demonstrating shareability of multipartite Einstein-Podolsky-Rosen steering

TL;DR

This paper experimentally demonstrates the shareability of EPR steering in a three-qubit system, showing that multiple observers can steer a single party's state, which broadens understanding of multipartite quantum correlations.

Contribution

The first experimental demonstration of shareability of EPR steering beyond monogamy constraints in a three-qubit system.

Findings

Confirmed shareability of EPR steering among multiple observers

Verified genuine three-qubit entanglement

Provides a new perspective on multipartite quantum correlations

Abstract

Einstein-Podolsky-Rosen (EPR) steering, a category of quantum nonlocal correlations describing the ability of one observer to influence another party's state via local measurements, is different from both entanglement and Bell nonlocality by possessing an asymmetric property. For multipartite EPR steering, the monogamous situation, where two observers cannot simultaneously steer the state of the third party, has been investigated rigorously both in theory and experiment. In contrast to the monogamous situation, the shareability of EPR steering in reduced subsystems allows the state of one party to be steered by two or more observers and thus reveals more configurations of multipartite EPR steering. However, the experimental implementation of such a kind of shareability has still been absent until now. Here, in an optical experiment, we provide a proof-of-principle demonstration of the shareability of EPR steering without the constraint of monogamy in a three-qubit system. Moreover, based on the reduced bipartite EPR steering detection results, we verify the genuine three-qubit entanglement results. This work provides a complementary viewpoint for understanding multipartite EPR steering and has potential applications in many quantum information protocols, such as multipartite entanglement detection, quantum cryptography, and the construction of quantum networks.