Experimental EPR-steering using Bell-local states

The concept of 'steering' was introduced in 1935 by Schrodinger(1) as a generalization of the EPR (Einstein-Podolsky- Rosen) paradox. It has recently been formalized as a quantum-information task with arbitrary bipartite states and measurements(2), for which the existence of entanglement is necessary but not sufficient. Previous experiments in this area(3-6) have been restricted to an approach(7) that followed the original EPR argument in considering only two different measurement settings per side. Here we demonstrate experimentally that EPR-steering occurs for mixed entangled states that are Bell local (that is, that cannot possibly demonstrate Bell non-locality). Unlike the case of Bell inequalities(8-11), increasing the number of measurement settings beyond two-we use up to six-significantly increases the robustness of the EPR-steering phenomenon to noise.