Reliable experimental certification of one-way Einstein-Podolsky-Rosen steering

TL;DR

This paper presents a reliable experimental demonstration of one-way Einstein-Podolsky-Rosen steering in a genuine two-qubit system, resolving previous ambiguities and providing a universal characterization method.

Contribution

It offers the first conclusive two-qubit experiment of one-way steering without high-dimensional assumptions, advancing the understanding of quantum correlations.

Findings

Successfully demonstrated one-way steering in two-qubit states

Provided a universal method for characterizing one-way steering

Resolved ambiguities from previous experiments

Abstract

Quantum steering is a recently-defined form of quantum correlation which lies at the heart of quantum mechanics. In difference from other types of quantum correlations, quantum steering is inherently asymmetric, which implies that it could manifest in one direction but not in the opposite direction. This rather peculiar phenomenon, known as one-way steering, have been demonstrated in several experiments, but subtlety remains. In fact all experiments were shown to be ambiguous until a very recent conclusive one, which however made a crucial use of a high dimensional embedding to get around assumptions. This leaves the question open whether the one-way steering phenomenon can be reliably demonstrated in the genuine two-qubit system. Here, we report such an experimental demonstration of one-way steering for a family of two-qubit states. Our experimental setup and results thus resolve the subtlety caused by fidelity assumption in previous experiments without the need of higher dimensional embedding. Moreover, our work provides a universal method to characterize one-way steering phenomenon for generic two-qubit states.